Tread rubber for new energy automobile and preparation method of tread rubber

Abstract

The invention relates to the technical field of rubber materials, and provides tread rubber for a new energy automobile and a preparation method thereof.The tread rubber is prepared from, by mass, 40-60 parts of chloroprene rubber, 40-60 parts of solution polymerized styrene-butadiene rubber, 40-50 parts of a reinforcing agent, 5-8 parts of a coupling agent, 2-4 parts of a vulcanizing agent, 2-4 parts of an anti-aging agent and 11-18 parts of a conductive system; the conductive system is obtained by doping 6-9 parts of an ionic liquid, 3-5 parts of a deep eutectic solvent, 2-4 parts of a conductive polymer and 1-2 parts of a separant. Through synergistic doping of the ionic liquid, the deep eutectic solvent and the conductive polymer, an electron-ion bicontinuous conductive network is constructed in a rubber matrix to meet the antistatic requirement, so that the design of a traditional conductive adhesive tape is eliminated, the process defects of adhesive tape alignment deviation, interface delamination, joint breakage and the like are avoided, and the service life of the conductive adhesive tape is prolonged. And the conductivity can be maintained for a long time.

Description

Technical Field

[0001] This invention relates to the field of rubber materials, and more specifically to a tread compound for new energy vehicles and its preparation method. Background Technology

[0002] With the rapid popularization of new energy vehicles, the problem of static electricity accumulation in vehicles is becoming increasingly prominent. During vehicle operation, the friction between the tires and the road surface continuously generates static charge. If the conductivity of the tire tread rubber is insufficient, the static electricity cannot be conducted to the ground in time through the tires. This can lead to minor interference with the vehicle's electronic systems, or even, under certain operating conditions, trigger a discharge spark, posing a certain safety hazard.

[0003] To reduce tire resistance and improve conductivity, existing technologies typically employ two approaches: one is to attach conductive rubber strips to the tire structure, such as the structure disclosed in patent CN222819845U, which increases tire conductivity by defining the position of the conductive rubber strips; the other is to add conductive carbon black (N550, N330) or graphene to the tread compound formulation, such as the formulation for an antistatic tread compound for all-steel tires disclosed in patent CN105949534A, which increases rubber conductivity by adding graphene as a conductive filler. However, the conductive rubber strip approach suffers from process defects such as alignment deviation, interface delamination, and joint breakage, making it difficult to guarantee the uniformity and long-term reliability of conductivity. While adding large amounts of carbon materials can improve conductivity, it significantly increases the hardness of the rubber compound and reduces resilience, leading to increased rolling resistance and tire energy consumption. Furthermore, the uniform dispersion of conductive carbon black in the rubber matrix is ​​difficult to control, resulting in poor batch consistency of conductivity, which contradicts energy conservation and emission reduction goals.

[0004] 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 tread compound for new energy vehicles and its preparation method are proposed, and the following technical solution is provided: A tread compound for new energy vehicles, by weight, comprises 40-60 parts of chloroprene rubber, 40-60 parts of solution-polymerized styrene-butadiene rubber, 40-50 parts of reinforcing agent, 5-8 parts of coupling agent, 2-4 parts of vulcanizing agent, 2-4 parts of antioxidant, and 11-18 parts of conductive system. The conductive system is obtained by doping with 6-9 parts of an ionic liquid, 3-5 parts of a deep eutectic solvent, 2-4 parts of a conductive polymer, and 1-2 parts of a release agent; the ionic liquid includes at least one of 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide, tetrabutylammonium tetrafluoroborate, or trihexyltetradecylphosphine chloride; the deep eutectic solvent includes choline chloride and / or glycerol; the conductive polymer includes polyaniline; and the release agent is selected from at least one of silica or calcium carbonate. The reinforcing agent is silica, the coupling agent is a sulfur-containing silane coupling agent or a mercaptosilane coupling agent, the vulcanizing agent is sulfur or a sulfur donor, and the antioxidant is at least one of an amine antioxidant or a physical antioxidant. The sulfur donor is at least one of a thiuram-type compound or a sulfur-containing morpholine derivative.

[0006] Furthermore, the doping method is either single-stage doping or two-stage doping.

[0007] Furthermore, the single-stage doping involves blending all raw materials together for doping.

[0008] Furthermore, the two-stage doping includes the following steps: first, stirring and mixing the ionic liquid with a deep eutectic solvent to obtain a mixed ionic conductor; continuing stirring and heating to 20-30°C, and then adding the conductive polymer in portions to the mixed ionic conductor while stirring to obtain a conductive system.

[0009] Furthermore, the first stirring and mixing is carried out at 40-50℃ for 10-15 minutes; the second stirring and mixing is carried out by raising the temperature to 70-80℃, increasing the stirring speed to 500-1000 rpm, and stirring for 30-60 minutes.

[0010] Furthermore, a separating agent is added during the second mixing process.

[0011] Preferably, the separating agent is silica.

[0012] Furthermore, the conductive polymer is vacuum dried at 50-60°C for 4-6 hours and then sieved.

[0013] Preferably, the conductive polymer after sieving is below 100 mesh.

[0014] Furthermore, the deep eutectic solvent is choline chloride and glycerol, and the mass ratio of choline chloride to glycerol is 1:2-3.

[0015] Furthermore, the reinforcing agent is silica, the coupling agent is a sulfur-containing silane coupling agent or a mercaptosilane coupling agent, the vulcanizing agent is sulfur or a sulfur donor, and the antioxidant is at least one of an amine antioxidant or a physical antioxidant.

[0016] Preferably, the sulfur-containing silane coupling agent is at least one of bis-[γ-(triethoxysilyl)propyl]tetrasulfide (Si-69) or bis-[γ-(triethoxysilyl)propyl]disulfide (Si-75); the mercaptosilane coupling agent is mercaptopropyltrimethoxysilane (Si-747). The sulfur is insoluble sulfur, and the sulfur donor is at least one of thiuram compounds or sulfur-containing morpholine derivatives. The sulfur donor is selected from tetramethylthiuram disulfide (TMTD) or dimorpholine disulfide (DTDM). The amine antioxidant is selected from N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine (6PPD), and the physical antioxidant is selected from protective wax.

[0017] This invention provides a method for preparing tire tread compound for new energy vehicles, comprising the following steps: Chloroprene rubber, solution-polymerized styrene-butadiene rubber, conductive system, reinforcing agent, coupling agent, and antioxidant are mixed and open-milled, followed by final milling. A vulcanizing agent is added during the final milling process. After the final milling is completed, vulcanization is carried out to obtain the tread rubber for new energy vehicles.

[0018] Furthermore, the mixing process includes the following steps: mixing chloroprene rubber and solution-polymerized styrene-butadiene rubber in a Banbury mixer, adding a conductive system, pressing the top plug for 20-40 seconds, and lifting the weight; then adding a coupling agent and a reinforcing agent, pressing the top plug for 25-35 seconds, and lifting the weight; pressing the top plug for 20-30 seconds, lifting the weight, and pressing the top plug again for 25-30 seconds; the Banbury mixer speed is 25-55 rpm, and the rubber is discharged at 150°C to obtain a first-stage compound. After remelting a section of the compound rubber, add the antioxidant, press the top plug for 25-35 seconds, lift the weight; press the top plug for 20-30 seconds, lift the weight, and press the top plug again for 20-30 seconds; the internal mixer speed is 30-50 rpm, discharge the rubber at 145℃, and let it stand for more than 8 hours.

[0019] Due to the adoption of the above technical solutions, the beneficial technical effects of the present invention are as follows: 1. This invention constructs an electron-ion dual continuous conductive network in the rubber matrix through the synergistic doping of ionic liquids, deep eutectic solvents and conductive polymers to meet antistatic requirements, thereby completely eliminating the design of traditional conductive adhesive strips, avoiding process defects such as adhesive strip misalignment, interface delamination, and joint breakage, and achieving long-term maintenance of conductivity.

[0020] 2. This invention employs a stepwise heating doping method. Low-temperature premixing ensures full miscibility between the ionic liquid and the deep eutectic solvent, forming a uniform doped medium. High-temperature, high-speed stirring allows the ionic liquid and deep eutectic solvent molecules to fully penetrate the conductive polymer molecular chains, achieving deep doping. The conductive polymer molecular chains transform from a coiled conformation to an extended conformation, significantly increasing the number of polarons and greatly enhancing intrinsic conductivity. The stepwise addition avoids localized agglomeration, ensuring uniform doping. This doping method enables the conductive system to form a complete conductive network with extremely low dosage, laying the microstructural foundation for subsequent uniform dispersion in the rubber matrix. Detailed Implementation

[0021] 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.

[0022] Unless otherwise specified in the examples, standard conditions or conditions recommended by the manufacturer should be followed. Reagents or instruments whose manufacturers are not specified are all commercially available products. Unless otherwise specified, all reagents used in the examples are commercially available.

[0023] This invention provides a tread compound for new energy vehicles, which, by weight, comprises 40-60 parts of chloroprene rubber (CR), 40-60 parts of solution-polymerized styrene-butadiene rubber (SSBR), 40-50 parts of reinforcing agent, 5-8 parts of coupling agent, 2-4 parts of vulcanizing agent, 2-4 parts of antioxidant, and 11-18 parts of conductive system. The conductive system is obtained by doping with 6-9 parts of ionic liquid, 3-5 parts of deep eutectic solvent, 2-4 parts of conductive polymer and 1-2 parts of release agent.

[0024] This invention constructs an electron-ion bicontinuous conductive network within the rubber matrix through the synergistic doping of ionic liquids, deep eutectic solvents, and conductive polymers, thereby stably reducing the volume resistivity of the tread rubber to 10. 5 -10 7 With a strength of Ω·cm, it fully meets the requirements for antistatic properties, thus completely eliminating the design of traditional conductive adhesive strips. This fundamentally avoids process defects such as adhesive strip misalignment, interface delamination, and joint breakage, achieving long-term maintenance of conductivity.

[0025] In this ternary composite system, the conductive polymer forms the solid framework, while the ionic liquid and deep eutectic solvent act as the liquid media. They form doped states through a series of strong physical and weak chemical interactions. The conductive polymer, such as polyaniline, contains amine (-NH-) and imine (=N-) groups on its main chain. In the undoped state, the electrons on these nitrogen atoms are localized. The ionic liquid or deep eutectic solvent provides protons (H+). + Alternatively, it can bind to nitrogen atoms on the polyaniline chain through charge transfer between its cations / anions. The protons or cations in the ionic liquid interact with the lone pair electrons of the imine nitrogen atoms on the polyaniline chain, forming a salt-like structure. Charges are introduced onto the polyaniline molecular chain, and these charges can move along the chain, thus enabling electrical conductivity.

[0026] Ionic liquids contain imidazole rings, which are planar aromatic structures. Conductive polymers (such as polyaniline) also contain numerous benzene and quinone rings in their molecular chains. These aromatic rings interact with each other via π-π stacking. This interaction allows the ionic liquid to adsorb onto the surface of the polymer chain, forming a solvation layer that helps stabilize the polymer chain conformation and promotes charge hopping between chains.

[0027] In the conductive system, the conductive polymer serves as the framework for electronic conductivity. Ionic liquids and deep eutectic solvents tightly encapsulate polyaniline through ionic bonds, hydrogen bonds, and π-π stacking, forming a conductive sheath. Chloroprene rubber, combined with solution-polymerized styrene-butadiene rubber, is tightly bonded to the conductive sheath through dipole-dipole interactions of chlorine atoms. After vulcanization, the entire conductive composite is stably locked within the cross-linked network of rubber through physical entanglement, hydrogen bonding, and dipole interactions, ensuring stable conductivity regardless of tire deformation or aging.

[0028] The doping method is either one-stage doping or two-stage doping.

[0029] The two-stage doping of the conductive system includes the following steps: First, the ionic liquid and the deep eutectic solvent are stirred and mixed to obtain a mixed ionic conductor; then, stirring is continued while the temperature is increased to 20-30°C, and a conductive polymer is added in portions to the mixed ionic conductor for a second stirring and mixing process to obtain the conductive system. This step-by-step heating doping method first premixes the ionic liquid and the deep eutectic solvent to form a uniform mixed ionic conductor, and then heats up and adds the conductive polymer in portions. This method ensures sufficient miscibility of the ionic conductor components through premixing, avoids local agglomeration of the conductive polymer through portioned addition, and promotes deep doping by allowing ionic conductor molecules to penetrate between the conductive polymer molecular chains, laying the foundation for the subsequent formation of a uniform and stable conductive network in the rubber matrix.

[0030] The ionic liquid comprises at least one of 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide, tetrabutylammonium tetrafluoroborate, or trihexyltetradecylphosphine chloride; the deep eutectic solvent comprises choline chloride and / or glycerol; and the conductive polymer comprises polyaniline. The deep eutectic solvent is choline chloride and glycerol, with a mass ratio of choline chloride to glycerol of 1:2-3.

[0031] In deep eutectic solvents (such as choline chloride and glycerol), glycerol is rich in hydroxyl groups (-OH), while choline chloride contains hydroxyl groups and chloride ions. These components themselves form a eutectic mixture through hydrogen bonding. When an ionic liquid is added, the ionic liquid also participates in the hydrogen bond network with glycerol. Furthermore, there is a strong ion-dipole interaction between the charged head groups in the ionic liquid and the polar hydroxyl groups of glycerol in the deep eutectic solvent, which allows the two to mix uniformly.

[0032] The first stirring and mixing involves stirring at 40-50℃ for 10-15 minutes; the second stirring and mixing involves raising the temperature to 70-80℃, increasing the stirring speed to 500-1000 rpm, and stirring at this temperature for 30-60 minutes. Premixing at 40-50℃ for 10-15 minutes allows the ionic liquid and deep eutectic solvent to become fully miscible; stirring at 70-80℃ and 500-1000 rpm for 30-60 minutes allows the ionic conductor to fully penetrate between the conductive polymer molecular chains. The original polyaniline molecular chains are in a coiled conformation, with tight packing and low charge delocalization, placing them in a semi-conductive state. This synergistic control of temperature and speed enables the doping of the conductive polymer. The insertion of the ionic liquid and deep eutectic solvent disrupts the hydrogen bonds and packing interactions between the molecular chains, causing the polyaniline molecular chains to expand, enhancing conjugated planarity, and expanding the delocalization range of polarons along the molecular chains, thereby significantly improving the intrinsic conductivity.

[0033] During the second mixing process, 1-2 parts of a release agent are added. The release agent is selected from silica or calcium carbonate. The addition of the release agent transforms the viscous conductive paste into a free-flowing granular masterbatch, solving the process problems of difficult feeding and uneven dispersion of high-polarity conductive composites in rubber compounding. At the same time, when silica is used, its surface silanol groups can chemically bond with the functional group-containing ionic liquids in the conductive system, covalently anchoring the conductive network to the surface of the reinforcing agent, effectively preventing the migration and ejection of ionic liquids, and significantly improving the dynamic stability of the conductive pathway.

[0034] The conductive polymer is vacuum dried at 50-60℃ for 4-6 hours and then sieved. Vacuum drying and sieving are pretreatments. Vacuum drying avoids the generation of bubbles during subsequent high-temperature mixing; sieving ensures uniform powder particle size, increases specific surface area, and is beneficial for the uniform adsorption and penetration of ionic conductors during subsequent doping processes.

[0035] The doping process of the conductive system in this invention is specifically as follows: Polyaniline powder was vacuum dried at 50-60℃ for 4-6 hours and passed through a 100-mesh sieve to obtain dried polyaniline powder. An ionic liquid was mixed with a deep eutectic solvent and stirred at 40-50℃ for 10-15 minutes to obtain a homogeneous mixed ionic conductor. Stirring was continued while the temperature was increased by 10-20℃. While stirring, the conductive polymer was added in portions to the mixed ionic conductor, raising the temperature to 70-80℃. The stirring speed was increased to 500-1000 rpm, and the mixture was kept at this temperature for 30-60 minutes. Silica was added during the stirring process. The endpoint of doping was determined by observing the color of the conductive system change from dark green to deep black and exhibiting an oily luster.

[0036] This invention also provides a method for preparing tread compound for new energy vehicles, comprising the following steps: Chloroprene rubber, solution-polymerized styrene-butadiene rubber, conductive system, reinforcing agent, coupling agent, and antioxidant are mixed and open-milled, followed by final milling. A vulcanizing agent is added during the final milling process, and vulcanization is carried out after the final milling is completed to obtain the tread rubber.

[0037] Specifically, the following steps are included: Chloroprene rubber and solution-polymerized styrene-butadiene rubber are mixed in an internal mixer. A conductive system is added, the top plug is pressed for 20-40 seconds, and the top plug is lifted. Then, coupling agent and reinforcing agent are added, the top plug is pressed for 25-35 seconds, and the top plug is lifted. The process is repeated, with the top plug pressed for 20-30 seconds and the top plug lifted again for 25-30 seconds. The internal mixer speed is 25-55 rpm, and the rubber is discharged at 150℃ to obtain a first-stage compound. After remelting a section of the compound rubber, add the antioxidant, press the top plug for 25-35 seconds, lift the weight; press the top plug for 20-30 seconds, lift the weight, and press the top plug again for 20-30 seconds; the internal mixer speed is 30-50 rpm, discharge the rubber at 145℃, and let it stand for more than 8 hours.

[0038] The rubber compound obtained in the above steps is pressed into a thin sheet on a two-roll mill for final mixing. A vulcanizing agent is added during the final mixing process. After the final mixing is completed, the rubber compound is sheeted to obtain the final rubber compound. The final rubber compound is vulcanized in a mold at 150-160℃ and 10-15 MPa for 15-25 minutes, then demolded and cooled to obtain the tread rubber.

[0039] The tread compound obtained by this invention can be used in the field of new energy vehicles. By introducing a conductive system formed by the synergistic doping of ionic liquid, deep eutectic solvent and conductive polymer into the tread compound formulation, an electron-ion dual continuous conductive network is constructed in the chloroprene rubber and solution-polymerized styrene-butadiene rubber matrix. This reduces the volume resistivity with low conductive component dosage, eliminates the structural safety hazards of conductive rubber strips, and balances mechanical properties and wet skid resistance without increasing rolling resistance. At the same time, the conductive network is covalently anchored to the surface of the reinforcing agent by the release agent, effectively preventing ionic liquid migration, thus achieving a balance between low energy consumption and stable static electricity discharge in new energy vehicle tires.

[0040] Example 1 Doping of conductive systems: Three parts of polyaniline powder were vacuum dried at 55°C for 5 hours and passed through a 100-mesh sieve to obtain dried polyaniline powder. Eight parts of 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt were mixed with one part of choline chloride and three parts of glycerol, and stirred at 45°C for 12 minutes to obtain a homogeneous mixed ionic conductor. The stirring was continued and the temperature was increased by 10°C. While stirring, the dried polyaniline powder was added to the mixed ionic conductor in three portions, and the temperature was raised to 75°C. The stirring speed was increased to 800 rpm, and the mixture was kept at this temperature and stirred for 40 minutes. Two parts of silica were added during the stirring process. The endpoint of doping was determined by observing the color of the conductive system change from dark green to deep black and exhibiting an oily luster.

[0041] Preparation of tread compound: Mix 50 parts of chloroprene rubber and 50 parts of solution-polymerized styrene-butadiene rubber in a mixer, add a conductive system, press the top plug for 30 seconds, and lift the weight; then add 7 parts of Si-69 and 40 parts of silica, press the top plug for 30 seconds, and lift the weight; press the top plug for 25 seconds, lift the weight, and press the top plug for another 25 seconds; the mixer speed is 40 rpm, and the rubber is discharged at 150℃ to obtain a first-stage compound. After remelting a section of the compound rubber, add 3 parts of 6PPD, press the top plug for 30 seconds, lift the weight; press the top plug for 25 seconds, lift the weight, and press the top plug again for 25 seconds; the internal mixer speed is 40 rpm, discharge the rubber at 145℃, and let it stand for more than 8 hours.

[0042] The rubber compound obtained in the above steps is pressed thinly on a two-roll mill for final mixing. Three parts of tetramethylthiuram disulfide are added during the final mixing process. After the final mixing is completed, the compound is sheeted to obtain the final rubber compound. The final rubber compound is vulcanized in a mold at 155°C and 12 MPa for 20 minutes, demolded and cooled to obtain the tread rubber.

[0043] Example 2 Compared to Example 1, in this example, the ionic liquid and deep eutectic solvent were not mixed beforehand when the conductive system was doped.

[0044] Doping of conductive systems: Three parts of polyaniline powder were vacuum dried at 55°C for 5 hours and passed through a 100-mesh sieve to obtain dried polyaniline powder. The dried polyaniline powder, eight parts of 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt, one part of choline chloride, and three parts of glycerol were mixed. The mixture was stirred at 45°C for 12 minutes, then the temperature was increased to 75°C, the stirring speed was increased to 800 rpm, and the mixture was kept at this temperature for 40 minutes. During the stirring process, two parts of silica were added. The endpoint of doping was determined by observing the color of the conductive system change from dark green to deep black and exhibiting an oily luster.

[0045] Preparation of tread compound: Mix 50 parts of chloroprene rubber and 50 parts of solution-polymerized styrene-butadiene rubber in a mixer, add a conductive system, press the top plug for 30 seconds, and lift the weight; then add 7 parts of Si-69 and 40 parts of silica, press the top plug for 30 seconds, and lift the weight; press the top plug for 25 seconds, lift the weight, and press the top plug for another 25 seconds; the mixer speed is 40 rpm, and the rubber is discharged at 150℃ to obtain a first-stage compound. After remelting a section of the compound rubber, add 3 parts of 6PPD, press the top plug for 30 seconds, lift the weight; press the top plug for 25 seconds, lift the weight, and press the top plug again for 25 seconds; the internal mixer speed is 40 rpm, discharge the rubber at 145℃, and let it stand for more than 8 hours.

[0046] The rubber compound obtained in the above steps is pressed thinly on a two-roll mill for final mixing. Three parts of tetramethylthiuram disulfide are added during the final mixing process. After the final mixing is completed, the compound is sheeted to obtain the final rubber compound. The final rubber compound is vulcanized in a mold at 155°C and 12 MPa for 20 minutes, demolded and cooled to obtain the tread rubber.

[0047] Example 3 Compared with Example 1, this example does not use a step-by-step temperature doping method when doping the conductive system.

[0048] Doping of conductive systems: Three parts of polyaniline powder were vacuum dried at 55°C for 5 hours and passed through a 100-mesh sieve to obtain dried polyaniline powder. Eight parts of 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt were mixed with one part of choline chloride and three parts of glycerol, and stirred at 65°C for 12 minutes to obtain a homogeneous mixed ionic conductor. Stirring continued, and the dried polyaniline powder was added to the mixed ionic conductor in three portions while stirring. The stirring speed was increased to 800 rpm, and the mixture was kept at this temperature for 40 minutes. Two parts of silica were added during the stirring process. The endpoint of doping was determined by observing the color of the conductive system change from dark green to deep black and exhibiting an oily luster.

[0049] Preparation of tread compound: Mix 50 parts of chloroprene rubber and 50 parts of solution-polymerized styrene-butadiene rubber in a mixer, add a conductive system, press the top plug for 30 seconds, and lift the weight; then add 7 parts of Si-69 and 40 parts of silica, press the top plug for 30 seconds, and lift the weight; press the top plug for 25 seconds, lift the weight, and press the top plug for another 25 seconds; the mixer speed is 40 rpm, and the rubber is discharged at 150℃ to obtain a first-stage compound. After remelting a section of the compound rubber, add 3 parts of 6PPD, press the top plug for 30 seconds, lift the weight; press the top plug for 25 seconds, lift the weight, and press the top plug again for 25 seconds; the internal mixer speed is 40 rpm, discharge the rubber at 145℃, and let it stand for more than 8 hours.

[0050] The rubber compound obtained in the above steps is pressed thinly on a two-roll mill for final mixing. Three parts of tetramethylthiuram disulfide are added during the final mixing process. After the final mixing is completed, the compound is sheeted to obtain the final rubber compound. The final rubber compound is vulcanized in a mold at 155°C and 12 MPa for 20 minutes, demolded and cooled to obtain the tread rubber.

[0051] Example 4 Compared to Example 1, in this example, the conductive polymer is not vacuum dried when the conductive system is doped.

[0052] Doping of conductive systems: Eight parts of 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt were mixed with one part of choline chloride and three parts of glycerol. The mixture was stirred at 45°C for 12 minutes to obtain a homogeneous mixed ionic conductor. The stirring was continued and the temperature was increased by 10°C. While stirring, three parts of polyaniline powder were added to the mixed ionic conductor in three portions, raising the temperature to 75°C. The stirring speed was increased to 800 rpm, and the mixture was kept at this temperature and stirred for 40 minutes. Two parts of silica were added during the stirring process. The endpoint of doping was determined by observing the color of the conductive system change from dark green to deep black and exhibiting an oily luster.

[0053] Preparation of tread compound: Mix 50 parts of chloroprene rubber and 50 parts of solution-polymerized styrene-butadiene rubber in a mixer, add a conductive system, press the top plug for 30 seconds, and lift the weight; then add 7 parts of Si-69 and 40 parts of silica, press the top plug for 30 seconds, and lift the weight; press the top plug for 25 seconds, lift the weight, and press the top plug for another 25 seconds; the mixer speed is 40 rpm, and the rubber is discharged at 150℃ to obtain a first-stage compound. After remelting a section of the compound rubber, add 3 parts of 6PPD, press the top plug for 30 seconds, lift the weight; press the top plug for 25 seconds, lift the weight, and press the top plug again for 25 seconds; the internal mixer speed is 40 rpm, discharge the rubber at 145℃, and let it stand for more than 8 hours.

[0054] The rubber compound obtained in the above steps is pressed thinly on a two-roll mill for final mixing. Three parts of tetramethylthiuram disulfide are added during the final mixing process. After the final mixing is completed, the compound is sheeted to obtain the final rubber compound. The final rubber compound is vulcanized in a mold at 155°C and 12 MPa for 20 minutes, demolded and cooled to obtain the tread rubber.

[0055] Example 5 Compared to Example 1, the deep eutectic solvent in this example is 4 parts glycerol.

[0056] Doping of conductive systems: Three parts of polyaniline powder were vacuum dried at 55°C for 5 hours and passed through a 100-mesh sieve to obtain dried polyaniline powder. Eight parts of 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt were mixed with four parts of glycerol and stirred at 45°C for 12 minutes to obtain a homogeneous mixed ionic conductor. The mixture was stirred further and heated by 10°C. While stirring, the dried polyaniline powder was added to the mixed ionic conductor in three portions, raising the temperature to 75°C. The stirring speed was increased to 800 rpm, and the mixture was kept at this temperature and stirred for 40 minutes. Two parts of silica were added during the stirring process. The endpoint of doping was determined by observing the color of the conductive system change from dark green to deep black and exhibiting an oily luster.

[0057] Preparation of tread compound: Mix 50 parts of chloroprene rubber and 50 parts of solution-polymerized styrene-butadiene rubber in a mixer, add a conductive system, press the top plug for 30 seconds, and lift the weight; then add 7 parts of Si-69 and 40 parts of silica, press the top plug for 30 seconds, and lift the weight; press the top plug for 25 seconds, lift the weight, and press the top plug for another 25 seconds; the mixer speed is 40 rpm, and the rubber is discharged at 150℃ to obtain a first-stage compound. After remelting a section of the compound rubber, add 3 parts of 6PPD, press the top plug for 30 seconds, lift the weight; press the top plug for 25 seconds, lift the weight, and press the top plug again for 25 seconds; the internal mixer speed is 40 rpm, discharge the rubber at 145℃, and let it stand for more than 8 hours.

[0058] The rubber compound obtained in the above steps is pressed thinly on a two-roll mill for final mixing. Three parts of tetramethylthiuram disulfide are added during the final mixing process. After the final mixing is completed, the compound is sheeted to obtain the final rubber compound. The final rubber compound is vulcanized in a mold at 155°C and 12 MPa for 20 minutes, demolded and cooled to obtain the tread rubber.

[0059] Example 6 Compared with Example 1, this example changes the formulation and processing parameters of the tread compound.

[0060] Doping of conductive systems: Two parts of polyaniline powder were vacuum dried at 60℃ for 4 hours and passed through a 100-mesh sieve to obtain dried polyaniline powder. Six parts of 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt were mixed with one part of choline chloride and two parts of glycerol, and stirred at 45℃ for 12 minutes to obtain a homogeneous mixed ionic conductor. The stirring was continued and the temperature was increased by 10℃. While stirring, the dried polyaniline powder was added to the mixed ionic conductor in three portions, and the temperature was raised to 75℃. The stirring speed was increased to 500 rpm, and the mixture was kept at this temperature and stirred for 30 minutes. Two parts of silica were added during the stirring process. The endpoint of doping was determined by observing the color of the conductive system change from dark green to deep black and exhibiting an oily luster.

[0061] Preparation of tread compound: 40 parts of chloroprene rubber and 60 parts of solution-polymerized styrene-butadiene rubber were mixed in a Banbury mixer. A conductive system was added, the top plug was pressed for 40 seconds, and the top plug was lifted. Then 5 parts of Si-69 and 50 parts of silica were added, the top plug was pressed for 30 seconds, and the top plug was lifted. The top plug was pressed for 25 seconds, the top plug was lifted, and the top plug was pressed for another 25 seconds. The Banbury mixer was rotated at 55 rpm and the rubber was discharged at 150°C to obtain a first-stage compound. After remelting a section of the compound rubber, add 2 parts of 6PPD, press the top plug for 30 seconds, lift the weight; press the top plug for 25 seconds, lift the weight, and press the top plug again for 20 seconds; the internal mixer speed is 40 rpm, discharge the rubber at 145℃, and let it stand for more than 8 hours.

[0062] The rubber compound obtained in the above steps is pressed thinly on a two-roll mill for final mixing. Two parts of tetramethylthiuram disulfide are added during the final mixing process. After the final mixing is completed, the compound is sheeted to obtain the final rubber compound. The final rubber compound is vulcanized in a mold at 155°C and 12 MPa for 20 minutes, demolded and cooled to obtain the tread rubber.

[0063] Example 7 Compared with Example 1, this example changes the formulation and processing parameters of the tread compound.

[0064] Doping of conductive systems: Four parts of polyaniline powder were vacuum dried at 50°C for 6 hours and passed through a 100-mesh sieve to obtain dried polyaniline powder. Nine parts of 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt were mixed with two parts of choline chloride and three parts of glycerol, and stirred at 50°C for 12 minutes to obtain a homogeneous mixed ionic conductor. The stirring was continued and the temperature was increased by 10°C. While stirring, the dried polyaniline powder was added to the mixed ionic conductor in three portions, and the temperature was increased to 70°C. The stirring speed was increased to 1000 rpm, and the mixture was kept at this temperature and stirred for 60 minutes. One part of silica was added during the stirring process. The endpoint of doping was determined by observing the color of the conductive system change from dark green to deep black and exhibiting an oily luster.

[0065] Preparation of tread compound: 40 parts of chloroprene rubber and 60 parts of solution-polymerized styrene-butadiene rubber were mixed in a Banbury mixer. A conductive system was added, the top plug was pressed for 40 seconds, and the top plug was lifted. Then 5 parts of Si-69 and 50 parts of silica were added, the top plug was pressed for 30 seconds, and the top plug was lifted. The top plug was pressed for 25 seconds, the top plug was lifted, and the top plug was pressed for another 25 seconds. The Banbury mixer was rotated at 55 rpm and the rubber was discharged at 150°C to obtain a first-stage compound. After remelting a section of the compound rubber, add 4 parts of 6PPD, press the top plug for 30 seconds, lift the weight; press the top plug for 25 seconds, lift the weight, and press the top plug again for 20 seconds; the internal mixer speed is 40 rpm, discharge the rubber at 145℃, and let it stand for more than 8 hours.

[0066] The rubber compound obtained in the above steps is pressed into a thin sheet on a two-roll mill for final refining. Four parts of dimorpholine disulfide are added during the final refining process. After the final refining is completed, the compound is sheeted to obtain the final rubber compound. The final rubber compound is vulcanized in a mold at 155°C and 12 MPa for 20 minutes, then demolded and cooled to obtain the tread rubber.

[0067] Comparative Example 1 Compared with Example 1, this comparative example does not use a conductive system. Instead, the conductive system is replaced with 40 parts of carbon black N330. The rest of the formulation and process are the same as in Example 1.

[0068] Comparative Example 2 Compared with Example 1, this comparative example does not add a deep eutectic solvent, and the rest of the formulation and process are the same as in Example 1.

[0069] Comparative Example 3 Compared with Example 1, this comparative example does not add ionic liquid, but the rest of the formulation and process are the same as in Example 1.

[0070] Comparative Example 4 Compared with Example 1, this comparative example adds a conductive system, and the deep eutectic solvent is choline chloride and glycerol, with a mass ratio of choline chloride to glycerol of 4:1.

[0071] Comparative Example 5 Compared with Example 1, no isolating agent is added when the conductive system is doped in this example.

[0072] Doping of conductive systems: Three parts of polyaniline powder were vacuum dried at 55°C for 5 hours and passed through a 100-mesh sieve to obtain dried polyaniline powder. Eight parts of 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt were mixed with one part of choline chloride and three parts of glycerol, and stirred at 45°C for 12 minutes to obtain a homogeneous mixed ionic conductor. The stirring was continued and the temperature was increased by 10°C. While stirring, the dried polyaniline powder was added to the mixed ionic conductor in three portions, and the temperature was raised to 75°C. The stirring speed was increased to 800 rpm, and the mixture was kept at this temperature and stirred for 40 minutes. The endpoint of doping was determined by observing the color of the conductive system change from dark green to deep black and exhibiting an oily luster.

[0073] Preparation of tread compound: Mix 50 parts of chloroprene rubber and 50 parts of solution-polymerized styrene-butadiene rubber in a mixer, add a conductive system, press the top plug for 30 seconds, and lift the weight; then add 7 parts of Si-69 and 40 parts of silica, press the top plug for 30 seconds, and lift the weight; press the top plug for 25 seconds, lift the weight, and press the top plug for another 25 seconds; the mixer speed is 40 rpm, and the rubber is discharged at 150℃ to obtain a first-stage compound. After remelting a section of the compound rubber, add 3 parts of 6PPD, press the top plug for 30 seconds, lift the weight; press the top plug for 25 seconds, lift the weight, and press the top plug again for 25 seconds; the internal mixer speed is 40 rpm, discharge the rubber at 145℃, and let it stand for more than 8 hours.

[0074] The rubber compound obtained in the above steps is pressed thinly on a two-roll mill for final mixing. Three parts of tetramethylthiuram disulfide are added during the final mixing process. After the final mixing is completed, the compound is sheeted to obtain the final rubber compound. The final rubber compound is vulcanized in a mold at 155°C and 12 MPa for 20 minutes, demolded and cooled to obtain the tread rubber.

[0075] The resulting tread compound showed the presence of air bubbles.

[0076] Test Example 1 The performance of the tread rubbers obtained in the examples and comparative examples was tested, and the specific test results are shown in Table 1 and Table 2.

[0077] Specifically, the volumetric conductivity of the tread compound was determined using GB / T 40719-2021, the dynamic mechanical properties of the tread compound were determined using GB / T 9870.1-2006, the tensile strength and elongation at break of the tread compound were determined using GB / T 528-2009, the tensile fatigue life of the tread compound was determined using GB / T 1688-2008, and the demosia flexural fatigue life of the tread compound was determined using GB / T 13934-2006.

[0078] Table 1 Performance testing of tread rubber in Examples 1-6 and Comparative Examples 1-4 Table 2 Mechanical property testing of tread rubber in Examples 1-6 and Comparative Examples 1-4 This invention uses chloroprene rubber and solution-polymerized styrene-butadiene rubber (SBR) as the rubber matrix. Both not only leverage their respective performance advantages but also create multiple synergistic effects with the ternary conductive system of ionic liquid / deep eutectic solvent / conductive polymer. In the conductive system, the conductive polymer acts as the electronic conductivity framework. The ionic liquid and deep eutectic solvent tightly encapsulate the polyaniline through ionic bonds / hydrogen bonds / π-π stacking, forming a conductive sheath. The polar chlorine atoms on the chloroprene rubber molecular chain tightly bind to the polar groups of the ionic liquid / deep eutectic solvent in the conductive system through dipole-dipole interactions, stabilizing the conductive sheath. Fixed within the rubber matrix, it effectively prevents the migration and ejection of ionic liquids; solution-polymerized styrene-butadiene rubber provides low rolling resistance and high wet skid resistance, working together with the silica reinforcement system to construct a mechanical support network; the polar gradient formed by the combined use of the two causes the conductive system to tend to accumulate in the chloroprene rubber phase region and its interface, achieving a more efficient conductive network with a lower amount of conductive component. At the same time, the polar anchoring effect of chloroprene rubber and the reinforcement network of solution-polymerized styrene-butadiene rubber interpenetrate each other, forming a dual network structure. Ultimately, without increasing the amount of carbon black or sacrificing rolling resistance, the volume resistivity of the tread rubber is stably reduced to 10. 5 -10 6 Ω·cm, achieving a comprehensive balance of high conductivity, excellent mechanical properties and low rolling resistance.

[0079] Example 1 fully implements all the technical solutions of the present invention, and its volume resistivity is 3.2 × 10⁻⁶. 5 Ω·cm, at 10 5 -10 6 The high conductivity range of Ω·cm meets the antistatic requirements of tires. This indicates that the conductive network constructed by the ternary synergy of ionic liquid, deep eutectic solvent, and conductive polymer has excellent conductivity efficiency. In Example 2, the ionic liquid and deep eutectic solvent were not premixed; although the antistatic requirements were still met, the resistivity was approximately 2.7 times higher than in Example 1. This shows that the premixing step helps to form a uniform mixed ionic conductor, ensuring uniform doping of the conductive polymer in the subsequent process. In Example 3, no stepwise temperature-increasing doping was used (direct mixing at 65°C), and the resistivity was approximately twice that of Example 1. This demonstrates that the stepwise temperature-increasing method of premixing at 40-50°C combined with high-temperature doping at 70-80°C is beneficial for the ionic conductor to fully penetrate the molecular chains of the conductive polymer, achieving deep doping. In Example 4, the polyaniline was not vacuum-dried; the resistivity was slightly higher than in Example 1, and the mechanical properties decreased. This demonstrates that the drying pretreatment to remove moisture has a positive effect on ensuring the doping effect and the performance of the vulcanizate. Example 5 used only glycerol as a deep eutectic solvent, and the resistivity increased by about 6.6 times compared with Example 1, indicating that the combination of choline chloride and glycerol can provide a better ionic conductive network.

[0080] Comparative Example 1 uses carbon black as the conductive system in the traditional scheme, with a resistivity of 3.1 × 10⁻⁶. 7While still exhibiting some conductivity, the resistivity in Comparative Example 1 is significantly higher than that in Example 1, and the tan δ at 60°C is as high as 0.156, indicating that traditional carbon black solutions have limitations in balancing conductivity and low rolling resistance. This application addresses this limitation, ensuring low resistance without affecting the rolling resistance of the tread compound. Comparative Example 2, which lacks a deep eutectic solvent, and Comparative Example 3, which lacks an ionic liquid, demonstrate that both deep eutectic solvents and ionic liquids are indispensable, and their synergistic effect with the conductive polymer is crucial for constructing a complete conductive network. Comparative Example 5, which does not add a release agent, shows an increase in resistivity of one order of magnitude compared to Example 1, and bubbles appear during processing, proving that the release agent not only improves processing performance, but its physical adsorption and chemical anchoring effects also significantly contribute to the formation and stability of the conductive network.

[0081] 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 tire tread compound for new energy vehicles, characterized in that, By weight, its raw materials include 40-60 parts of chloroprene rubber, 40-60 parts of solution-polymerized styrene-butadiene rubber, 40-50 parts of reinforcing agent, 5-8 parts of coupling agent, 2-4 parts of vulcanizing agent, 2-4 parts of antioxidant and 11-18 parts of conductive system. The conductive system is obtained by doping with 6-9 parts of an ionic liquid, 3-5 parts of a deep eutectic solvent, 2-4 parts of a conductive polymer, and 1-2 parts of a release agent; the ionic liquid includes at least one of 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide, tetrabutylammonium tetrafluoroborate, or trihexyltetradecylphosphine chloride; the deep eutectic solvent includes choline chloride and / or glycerol; the conductive polymer includes polyaniline; and the release agent is selected from at least one of silica or calcium carbonate. The reinforcing agent is silica, the coupling agent is a sulfur-containing silane coupling agent or a mercaptosilane coupling agent, the vulcanizing agent is sulfur or a sulfur donor, and the antioxidant is at least one of an amine antioxidant or a physical antioxidant. The sulfur donor is at least one of a thiuram compound or a sulfur-containing morpholine derivative.

2. The tire tread compound for new energy vehicles according to claim 1, characterized in that, The doping method is either one-stage doping or two-stage doping.

3. The tire tread compound for new energy vehicles according to claim 2, characterized in that, The two-stage doping process includes the following steps: first, stirring and mixing the ionic liquid with a deep eutectic solvent to obtain a mixed ionic conductor; continuing stirring and heating to 20-30°C; and second, adding the conductive polymer to the mixed ionic conductor in portions while stirring to obtain a conductive system.

4. The tire tread compound for new energy vehicles according to claim 3, characterized in that, The first stirring and mixing is carried out at 40-50℃ for 10-15 minutes; the second stirring and mixing is carried out by raising the temperature to 70-80℃, increasing the stirring speed to 500-1000 rpm, and stirring for 30-60 minutes.

5. The tire tread compound for new energy vehicles according to claim 3, characterized in that, Add the separating agent during the second mixing process.

6. The tire tread compound for new energy vehicles according to claim 3, characterized in that, The conductive polymer is vacuum dried at 50-60℃ for 4-6 hours and then sieved.

7. The tire tread compound for new energy vehicles according to claim 1, characterized in that, The deep eutectic solvent is choline chloride and glycerol, and the mass ratio of choline chloride to glycerol is 1:2-3.

8. A method for preparing a tread compound for new energy vehicles according to any one of claims 1-7, characterized in that, Includes the following steps: Chloroprene rubber, solution-polymerized styrene-butadiene rubber, conductive system, reinforcing agent, coupling agent, and antioxidant are mixed and open-milled, followed by final milling. A vulcanizing agent is added during the final milling process. After the final milling is completed, vulcanization is carried out to obtain the tread rubber for new energy vehicles.

9. The method for preparing a tread compound for new energy vehicles according to claim 8, characterized in that, The mixing process includes the following steps: chloroprene rubber and solution-polymerized styrene-butadiene rubber are mixed in an internal mixer; a conductive system is added; the top plug is pressed for 20-40 seconds, and the top plug is lifted; then a coupling agent and a reinforcing agent are added; the top plug is pressed for 25-35 seconds, and the top plug is lifted; the top plug is pressed for 20-30 seconds, and the top plug is lifted again for 25-30 seconds; the internal mixer speed is 25-55 rpm, and the rubber is discharged at 150°C to obtain a first-stage mixed rubber. After remelting a section of the compound rubber, add the antioxidant, press the top plug for 25-35 seconds, lift the weight; press the top plug for 20-30 seconds, lift the weight, and press the top plug again for 20-30 seconds; the internal mixer speed is 30-50 rpm, discharge the rubber at 145℃, and let it stand for more than 8 hours.

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