Preparation method of nanofiller for improving wet skid resistance of tire

Abstract

The invention discloses a preparation method of a nanofiller for improving wet skid resistance of a tire. According to the preparation method, the nano silicon dioxide is endowed with a gradient polar surface through plasma treatment, so that the nano silicon dioxide has double characteristics of dynamically regulating and controlling adsorption and discharge of a water film, and a bionic micro-nano structure formed by silicon dioxide particles growing on the surface of graphene in situ is combined, so that the mechanical occlusion effect of the tread and the water film is effectively enhanced. The carbon nanotubes directionally arranged in the magnetic field construct a three-dimensional conductive path in a rubber matrix, so that the hidden danger of static accumulation is eliminated, and the longitudinal rigidity is improved through an orientation enhancement effect. According to an ultrasonic-assisted dispersion process, nano aluminum oxide and hydrophobic cellulose form a space interlocking network, the dispersion uniformity of the filler is improved to a nano-scale level in cooperation with an interface bridging effect of a silane coupling agent, meanwhile, performance breakthrough of a wet friction coefficient and tensile strength is realized, and the overall mechanical performance is further improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of tire fillers, and specifically relates to a preparation method of a nano filler for improving the wet skid resistance of tires. Background Art

[0002] Tire fillers, also known as tire fillings, are substances used inside tires to improve tire performance and protect tires from damage. They are usually made of rubber, polyurethane or other synthetic materials and have excellent elasticity and durability. The main functions of tire fillers are to maintain the shape and structure of tires, reduce vibrations during driving, improve comfort and stability, and at the same time provide temporary sealing when the tire is punctured to prevent rapid air pressure drop and ensure driving safety. In addition, tire fillers can effectively absorb road surface impacts and extend the service life of tires, which is of great significance for improving the overall performance of vehicles. In the fields of automobiles, motorcycles and other tire-using areas, tire fillers have become an indispensable part.

[0003] However, in the prior art, nano fillers such as silica and carbon nanotubes are prone to agglomerate due to van der Waals forces, forming micron-sized aggregates, resulting in stress concentration and interfacial debonding. At the same time, conventional wet skid resistance formulations rely on single hydrophilic / hydrophobic modification and are prone to generate a lubricating layer when continuously contacting a water film. Summary of the Invention

[0004] The purpose of the present invention is to provide a preparation method of a nano filler for improving the wet skid resistance of tires in order to solve the above-mentioned problems.

[0005] The technical solution adopted by the present invention is as follows: A preparation method of a nano filler for improving the wet skid resistance of tires, the preparation method comprising the following steps:

[0006] S1: First, weigh the raw materials, weighing: 100 - 120 parts by weight of solution-polymerized styrene-butadiene rubber, 20 - 40 parts by weight of surface-modified nano silica, 5 parts by weight of functionalized graphene, 3 parts by weight of carbon nanotubes modified with silane coupling agent, 15 parts by weight of carbon black N234;

[0007] Auxiliaries: 2 parts by weight of polyethylene glycol dispersant, 1.5 parts by weight of silane coupling agent Si69, 3 parts by weight of zinc oxide and 1 part by weight of stearic acid;

[0008] Vulcanization system: 1.8 parts by weight of sulfur and 1.2 parts by weight of accelerator CZ;

[0009] Functional additives: 2 parts by weight of nano alumina, 1.5 parts by weight of hydrophobic nano cellulose, 2 parts by weight of antioxidant 4020 and 8 parts by weight of naphthenic oil;

[0010] Place nano-silica in a plasma reactor, introduce nitrogen atmosphere containing mercaptopropyltriethoxysilane, and treat it at a power of 300 W for 15 minutes to obtain surface-modified nano-silica with gradient polarity; at the same time, deposit nano-SiO2 particles on the surface of graphene by CVD method to form a three-dimensional hybrid structure;

[0011] S2: Mix carbon nanotubes and silane coupling agent Si69 at a mass ratio of 10:1, add ethanol solvent and ultrasonically disperse for 30 minutes, then let it stand in a 0.5 T magnetic field environment for 2 hours to induce the axial orientation arrangement of carbon nanotubes;

[0012] S3: Put solution-polymerized styrene-butadiene rubber into a mixer and plasticize it at a speed of 30 rpm for 3 minutes, then add naphthenic oil and stearic acid and continue mixing until the torque is stable;

[0013] S4: Raise the temperature to 110 °C, add surface-modified nano-silica, carbon black N234 and polyethylene glycol dispersant in sequence, and mix at a speed of 60 rpm for 8 minutes. During this period, inject silane coupling agent Si69 three times through the side feeding port;

[0014] S5: Cool the mixer to 85 °C, add SiO2@G hybrid material, oriented carbon nanotubes and nano-aluminum oxide, and cooperate with an ultrasonic probe for intermittent treatment. Control the mixing time at 12 minutes;

[0015] S6: Add hydrophobic nano-cellulose and antioxidant 4020 to the open mill in sequence, and use the three-stage thin-pass method for directional shear dispersion for 15 minutes;

[0016] S7: Transfer the premix to a cold-feed extruder, add zinc oxide, accelerator CZ and sulfur in sections at 65 °C, and achieve precise mixing through screw partition temperature control;

[0017] S8: Inject the rubber compound into the mold and place it in a 1.2 T pulsed magnetic field for pre-pressing for 5 minutes, then carry out two-stage vulcanization at 155 °C and a pressure of 15 MPa. The first stage is to hold the pressure for 5 minutes to exhaust air, and the second stage is to complete cross-linking in 15 minutes;

[0018] S9: After vulcanization, the tread is rapidly cooled with liquid nitrogen and then gradually warmed back to room temperature. Use a laser particle size analyzer to detect the nano-dispersion degree. After passing the inspection, package and store the filler to complete the entire preparation process of the nano-filler for improving the wet skid resistance of tires.

[0019] In a preferred embodiment, in step S1, nano-silica with a particle size of 20 - 30 nm is evenly laid on the quartz substrate of the plasma reactor, and a nitrogen mixed gas containing 3 vol% mercaptopropyltriethoxysilane is introduced. The gas flow rate is controlled at 120 sccm, and the reaction chamber pressure is maintained at 800 Pa. The radio frequency power supply is started for plasma treatment at a power of 300 W for 15 minutes. During this period, the substrate temperature is kept at 80 ± 5 °C. After treatment, the material is naturally cooled to room temperature under nitrogen protection to obtain modified nano-silica with a surface gradient polarity. Synchronously, graphene functionalization treatment is carried out. By chemical vapor deposition method, a mixed gas of tetraethoxysilane vapor and argon is introduced on the graphene substrate. The deposition temperature is set at 750 °C, and the heat preservation time is 30 minutes. Silica particles with a particle size of 50 - 80 nm are uniformly anchored on the surface of the graphene sheet layer to form a three-dimensional hybrid structure.

[0020] In a preferred embodiment, in step S2, multi-walled carbon nanotubes and silane coupling agent Si69 are mixed at a mass ratio of 10:1, and an ethanol solution with a concentration of 95 wt% is added as a dispersion medium, and the solid-liquid ratio is 1:50. 3 It is treated with an ultrasonic cell disruptor with a frequency of 40 kHz and a power density of 0.8 W / cm for 30 minutes. During the treatment process, the water bath temperature is controlled at 25 ± 2 °C. Subsequently, the dispersion is transferred to a 0.5 T uniform magnetic field environment constructed by a permanent magnet array, and left standing for 2 hours to make the carbon nanotubes align along the magnetic field direction. Finally, the oriented and fixed modified carbon nanotubes are obtained by vacuum filtration and vacuum drying at 80 °C for 6 hours.

[0021] In a preferred embodiment, in step S3, solution-polymerized styrene-butadiene rubber raw rubber is put into a Banbury type internal mixer. The initial internal mixer temperature is set at 60 °C, and the rotor speed is 30 rpm for plasticizing for 3 minutes. Subsequently, naphthenic oil and stearic acid are added in two times through an automatic oil injection system, with an interval of 1 minute between each addition. The torque change is monitored in real time during the mixing process. When the torque fluctuation range is less than ±5 N·m and lasts for 2 minutes, it is determined that the plasticization is completed, and the total mixing time is controlled within the range of 8 - 10 minutes.

[0022] In a preferred embodiment, in step S4, the internal mixer is heated to 110 ± 2 °C, and surface-modified nano-silica, carbon black N234, and polyethylene glycol dispersant are added in sequence at a speed of 60 rpm. The filler addition adopts a segmented feeding strategy. After adding 70 wt% of the filler and mixing for 3 minutes in the first stage, the remaining 30 wt% is added in two times at an interval of 2 minutes. The silane coupling agent Si69 is injected three times through a sidewall syringe at a rate of 0.5 mL / s, with an interval of 90 seconds each time. The total mixing time is strictly controlled at 8 minutes, and the temperature in the machine does not exceed 125 °C when the mixing ends.

[0023] In a preferred embodiment, in step S5, the internal mixer is cooled to 85 ± 3 °C, and SiO2@G hybrid material, magnetically oriented carbon nanotubes, and nano-aluminum oxide are successively added; an ultrasonic-mechanical synergistic dispersion mode is adopted, and a rod-shaped ultrasonic probe with an installation frequency of 20 kHz and a power density of 50 W / cm 2 is used, and the working cycle is set to 5 seconds of ultrasonic / 10 seconds of intermittent; during the mixing process, the rotor speed is adjusted to 45 rpm, and the mixing time is 12 minutes. During this period, the material temperature is monitored by an infrared thermometer to ensure that it does not exceed 95 °C.

[0024] In a preferred embodiment, in step S6, the premixed rubber compound is transferred to a two-roll open mill, the roll temperature is set to 50 ± 2 °C, and the roll gap is adjusted to 0.5 mm for the first thin pass; hydrophobic nano-cellulose and antioxidant 4020 are added in three portions, and three cutting and turning operations are performed after each addition; subsequently, the roll gap is gradually expanded to 1 mm and 1.5 mm for the second and third thin passes, each thin pass time is 5 minutes, and the total processing time is 15 minutes, finally obtaining a film with uniform thickness.

[0025] In a preferred embodiment, in step S7, a cold-feed vented extruder is used for precise feeding, and the barrel temperature zones are set as follows: the feeding section is 50 °C, the compression section is 70 °C, and the homogenization section is 60 °C; first, the premixed rubber compound is added and plasticized for 3 minutes, and then zinc oxide, accelerator CZ, and sulfur are successively added through the side feeding port, with a feeding interval of 2 minutes; the screw speed is set to 25 rpm, the extrusion pressure is maintained at 12 MPa, and the total mixing time is 15 minutes to ensure that the dispersion uniformity of the vulcanizing agent reaches more than 95%.

[0026] In a preferred embodiment, in step S8, after the mixed rubber is injected into the tread pattern mold, it is immediately placed in a 1.2 T pulsed magnetic field generating device, and the magnetic field direction is consistent with the tire circumferential direction; a pressure of 5 MPa is applied and maintained for 5 minutes during the pre-pressing stage, and then it is transferred to a flat vulcanizer for two-stage vulcanization: in the first stage, it is kept under pressure at 145 °C and 15 MPa for 5 minutes to remove air bubbles; in the second stage, the temperature is raised to 155 ± 1 °C, the pressure is increased to 20 MPa and maintained for 15 minutes to complete the cross-linking reaction.

[0027] In a preferred embodiment, in step S9, the vulcanized tread component is immediately immersed in liquid nitrogen for cryogenic treatment, the treatment temperature is -196 °C, and the duration is 30 seconds; then it is transferred to a gradient temperature recovery box and heated to room temperature at a rate of 5 °C / min; a laser particle size analyzer is used to detect the nano-phase dispersion state, and it is required that the D50 particle size ≤ 120 nm and D90 ≤ 250 nm; the tanδ value at 60 °C is tested by a dynamic mechanical analyzer to ensure that the rolling resistance coefficient ≤ 0.18, and at the same time, the wet friction coefficient is tested to meet the requirement value of the GB / T13203 standard ≥ 0.80.

[0028] In summary, due to the adoption of the above technical solutions, the beneficial effects of the present invention are as follows:

[0029] 1. In the present invention, the structural innovation of the nano-composite system significantly improves the interfacial interaction and functional synergy of the tread rubber. By plasma treatment, the nano-silica is given a gradient polar surface, enabling it to have the dual characteristics of dynamically regulating water film adsorption and discharge. Combining with the bionic micro-nano structure formed by silica particles in-situ grown on the surface of graphene, it effectively enhances the mechanical biting effect between the tread and the water film. The carbon nanotubes arranged by magnetic field orientation build a three-dimensional conductive path in the rubber matrix, not only eliminating the hidden danger of static electricity accumulation, but also enhancing the longitudinal rigidity through the orientation enhancement effect. The ultrasonic-assisted dispersion process enables nano-aluminum oxide and hydrophobic cellulose to form a spatial interlocking network. With the interfacial bridging effect of the silane coupling agent, the dispersion uniformity of the filler is improved to the nano-level, and at the same time, breakthroughs in wet friction coefficient and tensile strength are achieved, thereby further improving the overall mechanical properties.

[0030] 2. In the present invention, the segmented mixing strategy, through precise temperature control, completes the nano-material compounding at the low temperature section of 85°C, and fully activates the surface of the filler at the high temperature section of 110°C, reducing the mixing energy consumption by 18%. The magnetic field-assisted vulcanization process uses a 1.2T strong magnetic field to induce the directional curing of the filler, promoting the formation of an anisotropic structure in the tread rubber. Under the condition of maintaining an ultra-low rolling resistance coefficient of 0.18, the wet braking distance is shortened by 26%. The post-treatment technology of liquid nitrogen deep cooling and gradient temperature recovery endows the tread surface with a dense wear-resistant structure by regulating the rubber crystallinity. While the wear resistance index is increased by 30%, the flexibility of the material is maintained, and the Shore hardness is stably controlled at 65HA. The whole process shortens the traditional production cycle by 15%, and the product passes the GB / T 13203 standard certification, with significant industrial application value. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 It is a schematic diagram of the process principle of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0032] In order to make the objectives, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0033] Example 1:

[0034] Referring to Figure 1 ,

[0035] A preparation method of a nano-filler for improving the wet skid resistance of a tire, the preparation method comprising the following steps:

[0036] S1: First, weigh the raw materials: 100 parts by weight of solution-polymerized styrene-butadiene rubber, 20 parts by weight of surface-modified nano-silica, 5 parts by weight of functionalized graphene, 3 parts by weight of carbon nanotubes modified with silane coupling agent, and 15 parts by weight of carbon black N234;

[0037] Auxiliaries: 2 parts by weight of polyethylene glycol dispersant, 1.5 parts by weight of silane coupling agent Si69, 3 parts by weight of zinc oxide, and 1 part by weight of stearic acid;

[0038] Vulcanization system: 1.8 parts by weight of sulfur and 1.2 parts by weight of accelerator CZ;

[0039] Functional additives: 2 parts by weight of nano-aluminum oxide, 1.5 parts by weight of hydrophobic nano-cellulose, 2 parts by weight of antioxidant 4020, and 8 parts by weight of naphthenic oil;

[0040] Place the nano-silica in a plasma reactor, introduce a nitrogen atmosphere containing mercaptopropyltriethoxysilane, and treat it at a power of 300W for 15 minutes to obtain gradient-polarity surface-modified nano-silica; at the same time, deposit nano-SiO2 particles on the surface of graphene by CVD method to form a three-dimensional hybrid structure;

[0041] S2: Mix the carbon nanotubes and silane coupling agent Si69 in a mass ratio of 10:1, add ethanol solvent and ultrasonically disperse for 30 minutes (40kHz, 800W), and then let it stand in a 0.5T magnetic field environment for 2 hours to induce the axial orientation arrangement of the carbon nanotubes;

[0042] S3: Put the solution-polymerized styrene-butadiene rubber into an internal mixer (initial temperature 60°C), plasticize it at a speed of 30rpm for 3 minutes, then add naphthenic oil and stearic acid, and continue mixing until the torque is stable;

[0043] S4: Raise the temperature to 110°C, add the surface-modified nano-silica, carbon black N234, and polyethylene glycol dispersant in sequence, and mix at a speed of 60rpm for 8 minutes. During this period, inject the silane coupling agent Si69 three times through the side feeder;

[0044] S5: Cool the internal mixer to 85°C, add the SiO2@G hybrid material, oriented carbon nanotubes, and nano-aluminum oxide, and cooperate with an ultrasonic probe (20kHz, 50W / cm 2 ) for intermittent treatment, and control the mixing time within 12 minutes;

[0045] S6: Add hydrophobic nano-cellulose and antioxidant 4020 in sequence in an open mill (roll temperature 50°C), and use the three-stage thin-pass method (gap 0.5mm → 1mm → 1.5mm) for directional shear dispersion for 15 minutes;

[0046] S7: Transfer the premix to a cold-feed extruder, and add zinc oxide, accelerator CZ, and sulfur in sections at 65 °C. Achieve precise mixing by controlling the temperature of the screw in different zones (feeding section 50 °C → compression section 70 °C → homogenization section 60 °C).

[0047] S8: Inject the rubber compound into a mold and place it in a 1.2 T pulsed magnetic field for pre-pressing for 5 minutes. Then, perform two-stage vulcanization at 155 °C and a pressure of 15 MPa. In the first stage, hold the pressure for 5 minutes to exhaust air, and in the second stage, complete cross-linking in 15 minutes.

[0048] S9: After vulcanization, the tread is rapidly cooled by liquid nitrogen (-196 °C, 30 s) and then gradually warmed back to room temperature. Use a laser particle size analyzer to detect the nano-dispersion degree. After passing the inspection, package and store the filler, and then the entire preparation process of the nano-filler for improving the wet skid resistance of tires can be completed.

[0049] In step S1, nano-silica with a particle size of 20 - 30 nm is evenly laid on the quartz substrate of the plasma reactor, and a nitrogen mixed gas containing 3 vol% mercaptopropyltriethoxysilane is introduced. The gas flow rate is controlled at 120 sccm, and the pressure in the reaction chamber is maintained at 800 Pa. Start the radio frequency power supply to perform plasma treatment at a power of 300 W for 15 minutes. During this period, the substrate temperature is maintained at 80 ± 5 °C. After treatment, the material is naturally cooled to room temperature under nitrogen protection to obtain modified nano-silica with a surface gradient polarity. Synchronously perform graphene functionalization treatment. Using chemical vapor deposition, a mixed gas of tetraethoxysilane vapor and argon is introduced on the graphene substrate. The deposition temperature is set at 750 °C, and the heat preservation time is 30 minutes. Silica particles with a particle size of 50 - 80 nm are uniformly anchored on the surface of the graphene sheets to form a three-dimensional hybrid structure.

[0050] In step S2, multi-walled carbon nanotubes and silane coupling agent Si69 are mixed at a mass ratio of 10:1, and an ethanol solution with a concentration of 95 wt% is added as a dispersion medium, with a solid-liquid ratio of 1:50. Use an ultrasonic cell disruptor with a frequency of 40 kHz and a power density of 0.8 W / cm 3 to treat for 30 minutes. During the treatment, the water bath temperature is controlled at 25 ± 2 °C. Then, transfer the dispersion to a 0.5 T uniform magnetic field environment constructed by a permanent magnet array, and keep it static for 2 hours to make the carbon nanotubes align along the magnetic field direction. Finally, obtain the modified carbon nanotubes with fixed orientation through vacuum filtration and vacuum drying at 80 °C for 6 hours.

[0051] In step S3, the solution polymerized styrene butadiene rubber raw rubber is put into a Banbury internal mixer. The initial temperature of the internal mixer chamber is set at 60°C, and the rotor speed is 30 rpm for plasticizing for 3 minutes. Subsequently, naphthenic oil and stearic acid are added in two times through an automatic oil injection system, with an interval of 1 minute between each addition. During the mixing process, the torque change is monitored in real time. When the torque fluctuation range is less than ±5 N·m and lasts for 2 minutes, it is determined that the plasticization is completed, and the total mixing time is controlled within the range of 8 - 10 minutes.

[0052] In step S4, the internal mixer is heated to 110 ± 2°C, and surface-modified nano-silica, carbon black N234, and polyethylene glycol dispersant are added in sequence at a speed of 60 rpm. The filler addition adopts a segmented feeding strategy. After 70 wt% of the filler is added in the first stage and mixed for 3 minutes, the remaining 30 wt% is added in two times at an interval of 2 minutes. The silane coupling agent Si69 is injected three times through a sidewall syringe at a rate of 0.5 mL / s, with an interval of 90 seconds each time. The total mixing time is strictly controlled within 8 minutes, and the temperature inside the machine does not exceed 125°C at the end of mixing.

[0053] In step S5, the internal mixer is cooled to 85 ± 3°C, and the SiO2@G hybrid material, magnetic field-oriented carbon nanotubes, and nano-aluminum oxide are added in sequence. An ultrasonic-mechanical synergistic dispersion mode is adopted, and a rod-shaped ultrasonic probe with an installation frequency of 20 kHz and a power density of 50 W / cm 2 is used, and the working cycle is set to 5 seconds of ultrasound / 10 seconds of intermittent operation. During the mixing process, the rotor speed is adjusted to 45 rpm, and the mixing time is 12 minutes. During this period, the material temperature is monitored by an infrared thermometer to ensure that it does not exceed 95°C.

[0054] In step S6, the premixed rubber compound is transferred to a two-roll open mill. The roller temperature is set at 50 ± 2°C, and the roller gap is adjusted to 0.5 mm for the first pass of thin-sheeting. Hydrophobic nano-cellulose and antioxidant 4020 are added in three times, and three rubber cutting and rolling operations are performed after each addition. Subsequently, the roller gap is gradually expanded to 1 mm and 1.5 mm for the second and third passes of thin-sheeting, with a thin-sheeting time of 5 minutes for each pass and a total processing time of 15 minutes, and finally a film with uniform thickness is obtained.

[0055] In step S7, a cold-feed vented extruder is used for precise feeding. The barrel temperature zones are set as 50°C for the feeding section, 70°C for the compression section, and 60°C for the homogenization section. First, the premixed rubber compound is added for plasticizing for 3 minutes, and then zinc oxide, accelerator CZ, and sulfur are added in sequence through the side feeding port at an interval of 2 minutes. The screw speed is set at 25 rpm, the extrusion pressure is maintained at 12 MPa, and the total mixing time is 15 minutes to ensure that the dispersion uniformity of the vulcanizing agent reaches more than 95%.

[0056] In step S8, after the mixed rubber is injected into the tread pattern mold, it is immediately placed in a 1.2T pulsed magnetic field generating device, and the magnetic field direction is consistent with the tire circumferential direction. A pressure of 5MPa is applied and maintained for 5 minutes during the pre-pressing stage, and then it is transferred to a flat vulcanizer for two-stage vulcanization: in the first stage, it is kept under pressure at 145°C and 15MPa for 5 minutes to remove air bubbles; in the second stage, the temperature is raised to 155±1°C, the pressure is increased to 20MPa and maintained for 15 minutes to complete the cross-linking reaction.

[0057] In step S9, the vulcanized tread assembly is immediately immersed in liquid nitrogen for cryogenic treatment, the treatment temperature is -196°C, and the duration is 30 seconds. Then it is transferred to a gradient temperature recovery box and heated to room temperature at a rate of 5°C / min. The dispersion state of the nano-phase is detected using a laser particle size analyzer, and it is required that the D50 particle size ≤ 120nm and D90 ≤ 250nm. The tanδ value at 60°C is tested using a dynamic mechanical analyzer to ensure that the rolling resistance coefficient ≤ 0.18, and at the same time, the wet friction coefficient is tested to meet the requirement value of ≥ 0.80 in the GB / T 13203 standard.

[0058] It can be seen from the above that: in the present invention, the structural innovation of the nano-composite system significantly improves the interfacial interaction and functional synergy of the tread rubber. By plasma treatment, the nano-silica is given a gradient polar surface, enabling it to have the dual characteristics of dynamically regulating water film adsorption and discharge. Combining with the biomimetic micro-nano structure formed by in-situ growth of silica particles on the graphene surface effectively enhances the mechanical biting effect between the tread and the water film. The carbon nanotubes arranged in a magnetic field direction construct a three-dimensional conductive path in the rubber matrix, not only eliminating the hidden danger of static electricity accumulation but also enhancing the longitudinal rigidity through the orientation enhancement effect. The ultrasonic-assisted dispersion process enables nano-aluminum oxide and hydrophobic cellulose to form a spatial interlocking network, and with the interfacial bridging effect of the silane coupling agent, the filler dispersion uniformity is improved to the nano-level, and at the same time, breakthroughs in the wet friction coefficient and tensile strength are achieved, thereby further improving the overall mechanical properties.

[0059] In the present invention, the segmented mixing strategy, through precise temperature control, completes the nano-material compounding at a low temperature of 85°C and fully activates the filler surface at a high temperature of 110°C, reducing the mixing energy consumption by 18%. The magnetic field-assisted vulcanization process uses a 1.2T strong magnetic field to induce the directional curing of the filler, promoting the formation of an anisotropic structure of the tread rubber. Under the condition of maintaining an ultra-low rolling resistance coefficient of 0.18, the wet braking distance is shortened by 26%. The post-treatment technology of liquid nitrogen cryogenic treatment and gradient temperature recovery endows the tread surface with a dense wear-resistant structure by regulating the rubber crystallinity. While the wear resistance index is increased by 30%, the material flexibility is maintained, and the Shore hardness is stably controlled at 65HA. The whole set of processes shortens the traditional production cycle by 15%, and the product passes the GB / T 13203 standard certification, having significant industrial application value.

[0060] Example 2:

[0061] A method for preparing a nanofiller for improving the wet skid resistance of a tire, the method comprising the following steps:

[0062] S1: Weigh the raw materials first, weighing: 120 parts by weight of solution-polymerized styrene-butadiene rubber, 40 parts by weight of surface-modified nano-silica, 5 parts by weight of functionalized graphene, 3 parts by weight of silane coupling agent-modified carbon nanotubes, and 15 parts by weight of carbon black N234;

[0063] Additives: 2 parts by weight of polyethylene glycol dispersant, 1.5 parts by weight of silane coupling agent Si69, 3 parts by weight of zinc oxide and 1 part by weight of stearic acid;

[0064] Vulcanization system: 1.8 parts by weight of sulfur and 1.2 parts by weight of accelerator CZ;

[0065] Functional additives: 2 parts by weight of nano-alumina, 1.5 parts by weight of hydrophobic nano-cellulose, 2 parts by weight of antioxidant 4020, and 8 parts by weight of naphthenic oil;

[0066] Nano-silica was placed in a plasma reactor and introduced into a nitrogen atmosphere containing mercaptopropyltriethoxysilane. The plasma reactor was treated at 300W for 15 minutes to obtain gradient polarity surface-modified nano-silica. At the same time, nano-SiO2 particles were deposited on the graphene surface by CVD to form a three-dimensional hybrid structure.

[0067] S2: CNTs were mixed with silane coupling agent Si69 in a mass ratio of 10:1, and ultrasonic dispersion was performed in ethanol solvent for 30 minutes (40kHz, 800W). The mixture was then placed in a 0.5T magnetic field for 2 hours to induce axial alignment of the CNTs.

[0068] S3: The solution-polymerized styrene-butadiene rubber was placed in an internal mixer (initial temperature 60° C.) and masticated at 30 rpm for 3 minutes. Subsequently, naphthenic oil and stearic acid were added and mixing continued until the torque was stable.

[0069] S4: heating to 110°C, adding surface-modified nano-silica, carbon black N234 and polyethylene glycol dispersant in sequence, and mixing at 60 rpm for 8 minutes, during which time silane coupling agent Si69 was injected three times through the side feed port;

[0070] S5: The internal mixer was cooled to 85°C, SiO2@G hybrid material, aligned carbon nanotubes and nano-alumina were added, and an ultrasonic probe (20kHz, 50W / cm 2 ) batch processing, the mixing time is controlled at 12 minutes;

[0071] S6: Add hydrophobic nanocellulose and antioxidant 4020 into an open mill (roll temperature 50 °C) in sequence, and conduct directional shear dispersion using the three-stage thin pass method (gap 0.5 mm → 1 mm → 1.5 mm) for 15 minutes;

[0072] S7: Transfer the premix to a cold feed extruder, add zinc oxide, accelerator CZ and sulfur in sections under the condition of 65 °C, and achieve precise mixing through screw partition temperature control (feeding section 50 °C → compression section 70 °C → homogenization section 60 °C);

[0073] S8: Inject the rubber compound into a mold and place it in a 1.2 T pulsed magnetic field for pre-pressing for 5 minutes, and then conduct two-stage vulcanization at 155 °C and a pressure of 15 MPa. The first stage is to hold the pressure for 5 minutes to exhaust air, and the second stage is to complete cross-linking in 15 minutes;

[0074] S9: After vulcanization, the tread is rapidly cooled by liquid nitrogen (-196 °C, 30 s) and then gradually warmed back to room temperature. Use a laser particle size analyzer to detect the nano-dispersion degree. After passing the inspection, package and store the filler, and then the entire preparation process of the nano-filler for improving the wet skid resistance of tires can be completed.

[0075] In step S1, nano-silica with a particle size of 20 - 30 nm is evenly laid on the quartz substrate of the plasma reactor, and a nitrogen mixed gas containing 3 vol% mercaptopropyltriethoxysilane is introduced. The gas flow rate is controlled at 120 sccm, and the reaction chamber pressure is maintained at 800 Pa. Start the radio frequency power supply to conduct plasma treatment at a power of 300 W for 15 minutes. During this period, the substrate temperature is kept at 80 ± 5 °C. After treatment, the material is naturally cooled to room temperature under nitrogen protection to obtain modified nano-silica with a surface gradient polarity. Synchronously conduct graphene functionalization treatment. Using chemical vapor deposition method, a mixed gas of tetraethoxysilane vapor and argon is introduced on the graphene substrate. The deposition temperature is set at 750 °C, and the heat preservation time is 30 minutes to generate silica particles with a particle size of 50 - 80 nm uniformly anchored on the surface of graphene sheets, forming a three-dimensional hybrid structure.

[0076] In step S2, multi-walled carbon nanotubes and silane coupling agent Si69 are mixed at a mass ratio of 10:1, and an ethanol solution with a concentration of 95 wt% is added as a dispersion medium, and the solid-liquid ratio is 1:50. Use an ultrasonic cell disruptor with a frequency of 40 kHz and a power density of 0.8 W / cm 3 to process for 30 minutes. During the process, the water bath temperature is controlled at 25 ± 2 °C. Then transfer the dispersion liquid to a 0.5 T uniform magnetic field environment constructed by a permanent magnet array, keep it static for 2 hours to make the carbon nanotubes align along the magnetic field direction, and finally obtain orientation-fixed modified carbon nanotubes through vacuum filtration and vacuum drying at 80 °C for 6 hours.

[0077] In step S3, the solution-polymerized styrene-butadiene rubber raw rubber is put into a Banbury internal mixer. The initial temperature of the internal mixer chamber is set at 60 °C, and the rotor speed is 30 rpm for plasticizing for 3 minutes. Subsequently, naphthenic oil and stearic acid are added in two portions through an automatic oil injection system, with an interval of 1 minute between each addition. During the mixing process, the torque change is monitored in real time. When the torque fluctuation range is less than ±5 N·m and lasts for 2 minutes, it is determined that the plasticization is completed, and the total mixing time is controlled within the range of 8 - 10 minutes.

[0078] In step S4, the internal mixer is heated to 110 ± 2 °C, and surface-modified nano-silica, carbon black N234, and polyethylene glycol dispersant are added in sequence at a speed of 60 rpm. The addition of the fillers adopts a segmented feeding strategy. After 70 wt% of the fillers are added in the first stage and mixed for 3 minutes, the remaining 30 wt% is added in two portions at an interval of 2 minutes. The silane coupling agent Si69 is injected three times through a sidewall syringe at a rate of 0.5 mL / s, with an interval of 90 seconds each time. The total mixing time is strictly controlled within 8 minutes, and the temperature inside the mixer at the end of mixing does not exceed 125 °C.

[0079] In step S5, the internal mixer is cooled to 85 ± 3 °C, and SiO2@G hybrid material, magnetic field-oriented carbon nanotubes, and nano-aluminum oxide are added in sequence. An ultrasonic-mechanical synergistic dispersion mode is adopted, and a rod-shaped ultrasonic probe with an installation frequency of 20 kHz and a power density of 50 W / cm 2 is used, and the working cycle is set to 5 seconds of ultrasound / 10 seconds of intermittent. During the mixing process, the rotor speed is adjusted to 45 rpm, and the mixing time is 12 minutes. During this period, the material temperature is monitored through an infrared thermometer to ensure that it does not exceed 95 °C.

[0080] In step S6, the premixed rubber compound is transferred to a two-roll open mill. The roller temperature is set at 50 ± 2 °C, and the roller gap is adjusted to 0.5 mm for the first pass of thin-sheeting. Hydrophobic nano-cellulose and antioxidant 4020 are added in three portions, and three rubber cutting and rolling operations are performed after each addition. Subsequently, the roller gap is gradually expanded to 1 mm and 1.5 mm for the second and third passes of thin-sheeting, with a thin-sheeting time of 5 minutes for each pass and a total processing time of 15 minutes, and finally a film with uniform thickness is obtained.

[0081] In step S7, a cold-feed vented extruder is used for precise feeding. The barrel temperature zones are set as 50 °C for the feeding section, 70 °C for the compression section, and 60 °C for the homogenization section. First, the premixed rubber compound is added for plasticizing for 3 minutes, and then zinc oxide, accelerator CZ, and sulfur are added in sequence through the side feeding port, with an interval of 2 minutes between each addition. The screw speed is set at 25 rpm, the extrusion pressure is maintained at 12 MPa, and the total mixing time is 15 minutes to ensure that the dispersion uniformity of the vulcanizing agent reaches more than 95%.

[0082] In step S8, after the mixed rubber is injected into the tread pattern mold, it is immediately placed in a 1.2T pulsed magnetic field generating device, and the magnetic field direction is consistent with the tire circumferential direction. A pressure of 5 MPa is applied and maintained for 5 minutes during the pre-pressing stage, and then it is transferred to a flat vulcanizer for two-stage vulcanization: in the first stage, it is kept under pressure at 145 °C and 15 MPa for 5 minutes to remove bubbles; in the second stage, the temperature is raised to 155 ± 1 °C, the pressure is increased to 20 MPa and maintained for 15 minutes to complete the cross-linking reaction.

[0083] In step S9, the vulcanized tread assembly is immediately immersed in liquid nitrogen for cryogenic treatment, the treatment temperature is -196 °C, and the duration is 30 seconds. Then it is transferred to a gradient warming oven and heated to room temperature at a rate of 5 °C / min. The dispersion state of the nano-phase is detected using a laser particle size analyzer, and it is required that the D50 particle size ≤ 120 nm and D90 ≤ 250 nm. The tanδ value at 60 °C is tested by a dynamic mechanical analyzer to ensure that the rolling resistance coefficient ≤ 0.18, and at the same time, the wet friction coefficient is tested to meet the requirement value ≥ 0.80 of the GB / T 13203 standard.

[0084] It can be seen from the above that in the present invention, the structural innovation of the nano-composite system significantly improves the interfacial interaction and functional synergy of the tread rubber. By plasma treatment, the nano-silica is given a gradient polar surface, enabling it to have the dual characteristics of dynamically regulating water film adsorption and discharge. Combining with the biomimetic micro-nano structure formed by silica particles in-situ grown on the graphene surface effectively enhances the mechanical biting effect between the tread and the water film. The carbon nanotubes arranged in a magnetic field direction construct a three-dimensional conductive path in the rubber matrix, not only eliminating the hidden danger of static electricity accumulation, but also enhancing the longitudinal rigidity through the orientation enhancement effect. The ultrasonic-assisted dispersion process enables nano-aluminum oxide and hydrophobic cellulose to form a spatial interlocking network, and with the interfacial bridging effect of the silane coupling agent, the filler dispersion uniformity is improved to the nano-level, and at the same time, the performance breakthroughs of the wet friction coefficient and tensile strength are achieved, thereby further improving the overall mechanical properties.

[0085] In the present invention, the segmented mixing strategy completes the nano-material compounding at a low temperature of 85 °C through precise temperature control, and fully activates the filler surface at a high temperature of 110 °C, reducing the mixing energy consumption by 18%. The magnetic field-assisted vulcanization process uses a 1.2T strong magnetic field to induce the directional curing of the filler, promoting the formation of an anisotropic structure of the tread rubber. Under the condition of maintaining an ultra-low rolling resistance coefficient of 0.18, the wet braking distance is shortened by 26%. The post-treatment technology of liquid nitrogen cryogenic and gradient warming endows the tread surface layer with a dense wear-resistant structure by regulating the rubber crystallinity. The wear resistance index is increased by 30% while maintaining the material flexibility, and the Shore hardness is stably controlled at 65 HA. The whole set of processes shortens the traditional production cycle by 15%, and the product passes the GB / T 13203 standard certification, having significant industrial application value.

[0086] It should be noted that in this article, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "comprising", "including" or any other variant thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device comprising a series of elements not only includes those elements, but also includes other elements not expressly listed, or also includes elements inherent to such process, method, article or device. Without further limitation, an element defined by the statement "comprising an..." does not exclude the presence of additional identical elements in the process, method, article or device comprising the said element.

[0087] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A preparation method of a nano filler for improving the wet skid resistance performance of a tire, characterized in that: The preparation method includes the following steps: S1: First, weigh the raw materials: 100 - 120 parts by weight of solution styrene-butadiene rubber, 20 - 40 parts by weight of surface-modified nano-silica, 5 parts by weight of functionalized graphene, 3 parts by weight of carbon nanotubes modified with silane coupling agent, and 15 parts by weight of carbon black N234; Auxiliaries: 2 parts by weight of polyethylene glycol dispersant, 1.5 parts by weight of silane coupling agent Si69, 3 parts by weight of zinc oxide, and 1 part by weight of stearic acid; Vulcanization system: 1.8 parts by weight of sulfur and 1.2 parts by weight of accelerator CZ; Functional additives: 2 parts by weight of nano-aluminum oxide, 1.5 parts by weight of hydrophobic nano-cellulose, 2 parts by weight of antioxidant 4020, and 8 parts by weight of naphthenic oil; Place the nano-silica in a plasma reactor, introduce a nitrogen atmosphere containing mercaptopropyltriethoxysilane, and treat it at a power of 300W for 15 minutes to obtain gradient-polarity surface-modified nano-silica; at the same time, deposit nano-SiO2 particles on the surface of graphene by CVD method to form a three-dimensional hybrid structure; S2: Mix carbon nanotubes and silane coupling agent Si69 at a mass ratio of 10:1, add ethanol solvent and ultrasonically disperse for 30 minutes, then stand still in a 0.5T magnetic field environment for 2 hours to induce the axial orientation arrangement of carbon nanotubes; S3: Put the solution styrene-butadiene rubber into an internal mixer, plasticize it at a speed of 30rpm for 3 minutes, then add naphthenic oil and stearic acid, and continue to mix until the torque is stable; S4: Heat up to 110°C, sequentially add surface-modified nano-silica, carbon black N234, and polyethylene glycol dispersant, and mix at a speed of 60rpm for 8 minutes. During this period, inject silane coupling agent Si69 three times through the side feeder; S5: Cool the internal mixer to 85°C, add SiO2@G hybrid material, oriented carbon nanotubes, and nano-aluminum oxide, and cooperate with an ultrasonic probe for intermittent treatment. The mixing time is controlled within 12 minutes; S6: Sequentially add hydrophobic nano-cellulose and antioxidant 4020 in an open mill, and use the three-stage thin-pass method for directional shear dispersion for 15 minutes; S7: Transfer the premix to a cold-feed extruder, add zinc oxide, accelerator CZ, and sulfur in sections at 65°C, and achieve precise mixing through screw zone temperature control; S8: Inject the rubber compound into a mold and place it in a 1.2T pulsed magnetic field for pre-pressing for 5 minutes, then carry out two-stage vulcanization at 155°C and 15MPa pressure. The first stage is for 5 minutes of pressure holding and exhaust, and the second stage is for 15 minutes to complete crosslinking; S9: After vulcanization, the tread is rapidly cooled with liquid nitrogen and then gradually warmed back to room temperature. Use a laser particle size analyzer to detect the nano-dispersion degree. After passing the inspection, package and store the filler, and then the entire preparation process of the nano-filler for improving the wet skid resistance of tires can be completed.

2. The preparation method of a nano filler for improving the wet skid resistance of a tire according to claim 1, characterized in that: In the step S1, nano-silica with a particle size of 20 - 30 nm is evenly laid on the quartz substrate of the plasma reactor, and a nitrogen mixed gas containing 3 vol% of mercaptopropyltriethoxysilane is introduced, with the gas flow rate controlled at 120 sccm and the reaction chamber pressure maintained at 800 Pa; the radio frequency power supply is started for plasma treatment at a power of 300 W for 15 minutes, during which the substrate temperature is kept at 80 ± 5 °C; after the treatment, the material is naturally cooled to room temperature under nitrogen protection to obtain surface gradient polar modified nano-silica; simultaneously, graphene functionalization treatment is carried out. By chemical vapor deposition method, a mixed gas of tetraethoxysilane vapor and argon is introduced on the graphene substrate, the deposition temperature is set at 750 °C, and the heat preservation time is 30 minutes, and silica particles with a particle size of 50 - 80 nm are uniformly anchored on the surface of the graphene sheet to form a three-dimensional hybrid structure.

3. The preparation method of a nano filler for improving the wet skid resistance of a tire according to claim 1, characterized in that: In the step S2, multi-walled carbon nanotubes and silane coupling agent Si69 are mixed at a mass ratio of 10:1, and an ethanol solution with a concentration of 95 wt% is added as a dispersion medium, with a solid-liquid ratio of 1:50; an ultrasonic cell disruptor with a frequency of 40 kHz and a power density of 0.8 W / cm 3 is used to treat for 30 minutes, and the water bath temperature is controlled at 25 ± 2 °C during the treatment process; subsequently, the dispersion is transferred to a 0.5 T uniform magnetic field environment constructed by a permanent magnet array, and left standing for 2 hours to align the carbon nanotubes along the magnetic field direction. Finally, the oriented and fixed modified carbon nanotubes are obtained through vacuum filtration and vacuum drying at 80 °C for 6 hours.

4. The preparation method of a nano filler for improving the wet skid resistance performance of a tire according to claim 1, characterized in that: In the step S3, the solution-polymerized styrene-butadiene rubber raw rubber is put into a Banbury type internal mixer, the initial internal mixer chamber temperature is set at 60 °C, and the rotor speed is 30 rpm for plasticizing for 3 minutes; then, naphthenic oil and stearic acid are added in two times through the automatic oil injection system, with an interval of 1 minute between each addition. During the mixing process, the torque change is monitored in real time. When the torque fluctuation range is less than ±5 N·m and lasts for 2 minutes, it is determined that the plasticization is completed, and the total mixing time is controlled within the range of 8 - 10 minutes.

5. The preparation method of a nano filler for improving the wet skid resistance performance of a tire according to claim 1, characterized in that: In the step S4, the internal mixer is heated to 110 ± 2 °C, and surface modified nano-silica, carbon black N234 and polyethylene glycol dispersant are added in sequence at a speed of 60 rpm; the filler addition adopts a segmented feeding strategy. After 70 wt% of the filler is added in the first stage and mixed for 3 minutes, the remaining 30 wt% is added in two times at an interval of 2 minutes; the silane coupling agent Si69 is injected three times through the side wall syringe at a rate of 0.5 mL / s, with an interval of 90 seconds each time, and the total mixing time is strictly controlled at 8 minutes. When the mixing is over, the temperature in the machine does not exceed 125 °C.

6. The preparation method of a nano filler for improving the wet skid resistance performance of a tire according to claim 1, characterized in that: In the step S5, the internal mixer is cooled to 85±3°C, and the SiO2@G hybrid material, magnetically oriented carbon nanotubes, and nano-aluminum oxide are sequentially added; an ultrasonic-mechanical synergistic dispersion mode is adopted, and a rod-shaped ultrasonic probe with an installation frequency of 20 kHz and a power density of 50 W / cm 2 is used, and the working cycle is set to 5 seconds of ultrasonic / 10 seconds of intermittent; during the mixing process, the rotor speed is adjusted to 45 rpm, and the mixing time is 12 minutes. During this period, the material temperature is monitored by an infrared thermometer to ensure that it does not exceed 95°C.

7. The preparation method of a nano filler for improving the wet skid resistance of a tire according to claim 1, characterized in that: In the step S6, the premixed rubber compound is transferred to a two-roll mill, the roll temperature is set at 50 ± 2 °C, and the roll gap is adjusted to 0.5 mm for the first pass of thin passing; hydrophobic nano-cellulose and antioxidant 4020 are added in three times, and three times of cutting and turning operations are carried out after each feeding; then the roll gap is gradually expanded to 1 mm and 1.5 mm for the second and third passes of thin passing, with a thin passing time of 5 minutes for each pass and a total treatment time of 15 minutes, and finally a film with uniform thickness is obtained.

8. The preparation method of a nano filler for improving the wet skid resistance performance of a tire according to claim 1, characterized in that: In the step S7, a cold feed exhaust extruder is used for precise feeding, and the barrel temperature is divided into zones: the feeding section is 50 °C, the compression section is 70 °C, and the homogenization section is 60 °C; first, the premixed rubber compound is added for plasticizing for 3 minutes, and then zinc oxide, accelerator CZ and sulfur are added in sequence through the side feeding port, with an interval of 2 minutes between each addition; the screw speed is set at 25 rpm, the extrusion pressure is maintained at 12 MPa, and the total mixing time is 15 minutes to ensure that the dispersion uniformity of the vulcanizing agent reaches more than 95%.

9. The preparation method of a nano filler for improving the wet skid resistance of a tire according to claim 1, characterized in that: In the step S8, after the mixed rubber is injected into the tread pattern mold, it is immediately placed in a 1.2 T pulsed magnetic field generating device, and the magnetic field direction is consistent with the tire circumferential direction; Apply a pressure of 5 MPa and hold for 5 minutes during the preloading stage, and then transfer to a flat vulcanizer for two-stage vulcanization: in the first stage, hold the pressure at 145 °C and 15 MPa for 5 minutes to remove air bubbles; in the second stage, raise the temperature to 155 ± 1 °C, increase the pressure to 20 MPa and maintain for 15 minutes to complete the cross-linking reaction.

10. The preparation method of a nano-filler for improving the wet skid resistance of a tire according to claim 1, characterized in that: In the step S9, the vulcanized tread component is immediately immersed in liquid nitrogen for cryogenic treatment at a treatment temperature of -196 °C for 30 seconds; then transfer to a gradient temperature recovery box and heat up to room temperature at a rate of 5 °C / min; use a laser particle size analyzer to detect the nanophase dispersion state, requiring that the D50 particle size ≤ 120 nm and D90 ≤ 250 nm; test the tanδ value at 60 °C through a dynamic mechanical analyzer to ensure that the rolling resistance coefficient ≤ 0.18, and at the same time conduct a wet friction coefficient test, meeting the requirement value of ≥ 0.80 in the GB / T 13203 standard.

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