A self-repairing composite material for new energy vehicle tires, its preparation method and tires

Abstract

The present application discloses a self-repairing composite material for new energy vehicle tires, a preparation method thereof, and a tire, wherein the self-repairing composite material is composed of a first self-repairing layer and a second self-repairing layer connected together; the first self-repairing layer is prepared by including the following components by weight: 80-120 parts of a dynamic vulcanized rubber system, 18-35 parts of a functional filler system, and 3-8 parts of a vulcanization accelerator; the second self-repairing layer is prepared by including the following components by weight: 100-110 parts of a thermoplastic polyurethane elastomer, 30-40 parts of a repair microcapsule, and 10-15 parts of a modified polyimide fiber; the repair microcapsule is composed of a core material and a capsule wall, and the core material is an epoxy resin mixture or a curing agent mixture. The present application can meet the needs of rapid repair of new energy vehicle tires when they are damaged under complex road conditions by setting a double-layer self-repairing composite material, and has good durability, effectively protecting the safety of drivers and passengers.

Description

Technical Field

[0001] The present application relates to a self-repairing composite material for new energy vehicle tires, its preparation method and tires, and belongs to the field of tire materials. Background Art

[0002] With the development of new energy vehicles, electric vehicles and hybrid vehicles have gradually become the mainstream, and the market has higher and higher requirements for their driving range, power performance and safety. As an important part of the vehicle, the tire not only undertakes the main function of the vehicle contacting the ground, but also directly affects driving safety and comfort. During the driving of the vehicle, the problem of rapid air pressure drop caused by a punctured tire poses a threat to the personal safety of passengers and the stability of the vehicle.

[0003] Currently, some products of sealant repair adhesives have also been developed in the prior art. For example, in Chinese Patent Application CN114058293A - A self-repairing tire sealant and its preparation method and self-repairing tire, a self-repairing sealant is prepared with butyl rubber as the core and adding reinforcing fillers and other substances, which can avoid rapid gas leakage to a certain extent. However, in fact, the self-adhesion of butyl rubber is poor, and the glue may delaminate in the short term. In Chinese Patent Application CN116396605A - A disc-covered self-repairing sealant material for puncture prevention of new energy vehicle tires and its preparation method, it is proposed to use a modified polyurethane sealant material and an active filler, which can improve a certain durability.

[0004] However, in the actual application of new energy vehicle tires, there are complex performance requirements. New energy vehicles, especially electric vehicles, have a high torque output, which means that the tires bear a large load during starting, accelerating and braking. At the same time, during high-speed driving, heat accumulation will occur on the inner surface of the tire. The impact resistance and high-temperature resistance of ordinary repair materials are limited, and they may age during long-term driving, resulting in a weakened self-repair effect or loss of repair ability. High temperature will also accelerate the aging of tire materials, increasing cracks, wear and other damages on the tire surface. At the same time, under the dynamic stress of the tire, the traditional self-repairing adhesive may suffer fatigue damage, resulting in a decline in the repair effect. In addition, the existing self-repairing sealants can repair small punctures (such as thin nails), but have a poor repair effect on small-area irregular damages (such as multi-directional cracks caused by sharp fasteners) caused by the impact penetration of irregular penetrators or complex-shaped fasteners, and the damaged area will still gradually leak air, unable to form a good repair effect in a short time. Summary of the Invention

[0005] To solve the above problems, the present application proposes a self-repairing composite material for new energy vehicle tires, its preparation method and a tire. By providing a double-layer self-repairing composite material, the first layer on the outside can quickly respond to small punctures and minor cracks, and can quickly conduct heat and dissipate heat, avoiding heat accumulation in the heat area, having good high-temperature stability. The second layer on the inside can provide strong repair support, having high strength and lasting fatigue resistance, and can meet the requirements of quickly repairing new energy vehicle tires when damaged under complex road conditions, and has good durability, effectively protecting the safety of the driver and passengers.

[0006] According to one aspect of the present application, there is provided a self-repairing composite material for new energy vehicle tires, which is composed of a first self-repairing layer and a second self-repairing layer connected together;

[0007] By weight, the first self-repairing layer is prepared from the following components: 80 - 120 parts of a dynamically vulcanized rubber system, 18 - 35 parts of a functional filler system, and 3 - 8 parts of a vulcanization accelerator; the dynamically vulcanized rubber system includes polypropylene, natural rubber, and ethylene-propylene rubber, and the addition amount of polypropylene in the dynamically vulcanized rubber system does not exceed 30%; the functional filler system includes a heat-conducting filler, and the heat-conducting filler includes modified boron nitride and alumina; the vulcanization accelerator includes sulfur and N-cyclohexyl-2-benzothiazole sulfenamide;

[0008] By weight, the second self-repairing layer is prepared from the following components: 100 - 110 parts of thermoplastic polyurethane elastomer, 30 - 40 parts of repair microcapsules, and 10 - 15 parts of modified polyimide fibers; the repair microcapsules are composed of a core material and a capsule wall, and the core material is an epoxy resin mixture or a curing agent mixture.

[0009] By using a resin-phase polypropylene (PP) and a rubber phase (natural rubber NR + ethylene-propylene rubber EPDM) to form a dynamically vulcanized rubber system, first, PP acts as a continuous phase, playing a supporting and strengthening role, while the rubber phase provides flexibility and toughness. The two form a micro-dispersed structure through dynamic vulcanization, which can comprehensively improve the heat resistance, toughness, and durability of the composite material.

[0010] Furthermore, the rubber phase adopts the combination of NR + EPDM. With the high elasticity, low-temperature flexibility, and good tear resistance of natural rubber NR, it helps to absorb impacts and inhibit cracks under dynamic loads. Coupled with ethylene-propylene rubber (EPDM), it endows the material with stability in high-temperature environments and simultaneously improves the compatibility with functional fillers and the matrix.

[0011] By limiting the addition amount of polypropylene to not exceed 30%, it can ensure that the material has sufficient flexibility and crack propagation resistance, while maintaining a certain rigidity and heat resistance, enabling the material to adapt to the dynamic load environment of the tire.

[0012] Optionally, the weight ratio of natural rubber to ethylene-propylene rubber in the dynamically vulcanized rubber system is (2-3):1. Specifically, by defining the weight ratio of the two, not only can a stable interfacial structure between PP and the rubber phase be ensured, but it can also better adapt to high-temperature and high-torque environments and provide excellent impact absorption capacity.

[0013] Optionally, the weight ratio of modified boron nitride to alumina in the heat-conducting filler is (2-3):1;

[0014] The modified boron nitride includes silane-modified boron nitride and polymer-coated modified boron nitride, and the weight ratio is (1.5-2):1.

[0015] Specifically, the preparation method of silane-modified boron nitride is to dissolve the silane coupling agent KH550 in an ethanol solution (concentration 95%), stir evenly, add boron nitride, and react at 80°C for 2 h; after filtration, washing and drying, silane-modified boron nitride is obtained.

[0016] The preparation method of polymer-coated modified boron nitride is to disperse boron nitride in the solvent toluene, stir evenly, add the monomer acrylate and the initiator (ammonium persulfate), and carry out a polymerization reaction at 60°C; after the reaction is completed, the product is filtered, washed and dried to form modified boron nitride with a polymer-coated surface.

[0017] Specifically, the particle size of the modified boron nitride is 8-10 μm, and the particle size of the alumina is 1-3 μm.

[0018] By using modified boron nitride and alumina as the heat-conducting filler, it is possible to avoid material aging, performance degradation or damage caused by long-term high-temperature accumulation, and adapt to the high-temperature environment during high-torque and long-term operation of new energy vehicles. By using modified boron nitride, the interfacial bonding force with the matrix material is improved, the dispersion of the filler in the matrix is enhanced, and the interruption of the heat-conducting path is avoided, thereby enhancing the overall heat-conducting performance of the material. Alumina has a certain interfacial compatibility with the rubber matrix. The compounding of alumina and modified boron nitride can synergistically optimize the thermal conductivity and improve the mechanical properties through fillers with different particle sizes and morphologies.

[0019] The combination of two modified boron nitrides is adopted with the aim of optimizing its compatibility and dispersibility with the matrix at different levels: active groups are introduced on the surface of silane-modified boron nitride to enhance the interfacial bonding force with the matrix material (especially the rubber matrix), improve the chemical compatibility between the filler and the rubber phase, reduce the thermal resistance between interfaces, prevent the agglomeration of fillers, and ensure uniform dispersion in the matrix. Polymer-modified boron nitride can enhance its wettability and physical adsorption force in the rubber matrix, improve the durability of the filler, prevent it from falling off or precipitating under high-temperature and dynamic stress conditions, reduce the possible damage to the matrix material by the filler, and avoid adverse effects on the vulcanization process of the rubber phase. Generally speaking, silane modification enhances the chemical bonding force, and polymer coating provides physical enhancement. The combination of the two effectively optimizes the thermal conductivity and mechanical properties of boron nitride in the rubber matrix.

[0020] Optionally, the functional filler system further includes crack-inhibiting fillers and dynamic reinforcing fillers;

[0021] The weight ratio of the thermal conductive filler, crack-inhibiting filler, and dynamic reinforcing filler is (6 - 12):(3 - 7):(2 - 5) in sequence.

[0022] Preferably, the crack-inhibiting filler is silane-modified nano-silica powder, and the dynamic reinforcing filler is nano-ceria.

[0023] The particle size of nano-ceria is 20 - 50 nm, and the particle size of nano-silica powder is 10 - 50 nm.

[0024] The preparation method of silane-modified nano-silica powder is as follows:

[0025] a1. Clean the nano-silica powder: ultrasonically disperse the nano-silica powder in deionized water for 30 min to clean the impurities and particles that may adhere to the surface. After filtration, dry it with hot air at 60 °C to constant weight;

[0026] a2. Add the silane coupling agent KH550 according to the ratio of coupling agent: solvent = 1:10 (volume ratio) to anhydrous ethanol and stir evenly; add a small amount of deionized water (the hydrolysis ratio of silane is silane: water = 1:3, molar ratio), stir until completely dissolved, and then adjust the pH of the solution to 4 (using glacial acetic acid) to promote the hydrolysis of silane to form active groups.

[0027] a3. Add the dried nano-silica powder to the silane solution and stir evenly; perform ultrasonic treatment for 30 min to ensure uniform dispersion of the powder and prevent agglomeration. Place the mixed solution in a water bath at 80 °C and react for 2 h. After filtration and drying, it is obtained.

[0028] By adding crack suppression fillers and dynamic reinforcement fillers on the basis of the thermal conductive filler system, the silane-modified nano-silica powder can effectively passivate the crack tip, thereby delaying crack propagation. At the same time, under the action of dynamic load, cerium oxide particles can help disperse periodic stress in the material, preventing local material damage caused by stress concentration. Through the weak interaction with rubber segments, cerium oxide particles can also fill and stabilize the microscopic damage area, slowing down the rate of fatigue accumulation. The reasonable combination and synergistic effect of the two can effectively enhance the dynamic fatigue performance and crack propagation resistance of the composite material while improving the thermal conductivity, thus meeting the strict requirements of new energy vehicle tires in high-load and high-frequency usage environments.

[0029] Optionally, the weight ratio of sulfur to N-cyclohexyl-2-benzothiazole sulfenamide in the vulcanization accelerator is (1 - 1.5):1.

[0030] Optionally, the preparation method of the first self-repairing layer includes the following steps:

[0031] S1: Add polypropylene, natural rubber, and ethylene-propylene rubber into a Banbury mixer at a temperature of 155 - 165 °C and knead for 5 - 10 min;

[0032] S2: Then add the vulcanization accelerator, raise the temperature to 170 - 180 °C, dynamically knead for 3 - 5 min, and then add the functional filler system;

[0033] S3: Continue to knead for 2 - 4 min, and then press and form it through a two-roll mill to obtain the first self-repairing layer;

[0034] Preferably, in step S3, the pressure for press forming is 10 - 12 MPa, the temperature is 160 - 165 °C, and the time is 8 - 10 min.

[0035] Specifically, the rotation speed in steps S1 and S2 is 30 rpm, the thickness of the first self-repairing layer is 1 - 2 mm, preferably 1.5 mm.

[0036] Optionally, the repair microcapsules include type A microcapsules and type B microcapsules, and the weight ratio is (1.2 - 1.4):1;

[0037] The type A microcapsules are epoxy resin microcapsules, the core material is DGEBA epoxy resin and dibutylhydroxytoluene, and the weight ratio is (60 - 70):1, and the capsule wall is polymethyl methacrylate;

[0038] The type B microcapsules are curing agent microcapsules, the core material is tetraethylenepentamine and dibutylhydroxytoluene, and the weight ratio is (55 - 65):1, and the capsule wall is polyurea.

[0039] Specifically, the particle sizes of both type A microcapsules and type B microcapsules are 100 μm.

[0040] 1. The preparation method of Class A microcapsules is as follows:

[0041] a. Prepare the aqueous phase:

[0042] Add distilled water to a three-necked flask, add 3% PVA dispersant, and stir evenly to form a stable aqueous phase.

[0043] b. Prepare the core material mixture:

[0044] Mix DGEBA epoxy resin and dibutylhydroxytoluene according to the weight ratio, and heat to 40 °C to make them completely miscible.

[0045] c. Emulsify the core material:

[0046] Slowly drop the core material mixture into the aqueous phase, and at the same time stir at a high speed of 1500 rpm to form a stable emulsion.

[0047] d. Polymerize the capsule wall:

[0048] Add methyl methacrylate (MMA, capsule wall monomer) and a small amount of AIBN (initiator) to the emulsion, keep stirring and heat up to 75 °C, and carry out free radical polymerization reaction for 3 h.

[0049] e. Cooling and post-treatment:

[0050] After the reaction is completed, cool to room temperature (25 °C), filter out the microcapsules, wash them several times with distilled water, and finally dry them at 40 °C to obtain epoxy resin microcapsules.

[0051] 2. The preparation method of Class B microcapsules is as follows:

[0052] a. Prepare the aqueous phase:

[0053] Add distilled water to a three-necked flask, add 3% PVA dispersant, and stir evenly to form a stable aqueous phase.

[0054] b. Prepare the core material mixture:

[0055] Mix tetraethylenepentamine and dibutylhydroxytoluene according to the weight ratio.

[0056] c. Emulsify the core material:

[0057] Slowly drop the core material mixture into the aqueous phase, and at the same time stir at a high speed of 1500 rpm to form a stable emulsion.

[0058] d. Polymerize the capsule wall:

[0059] Isocyanate monomer (HDI) and PEG were added to the emulsion in proportion, and an organic amine catalyst (triethylamine) was added dropwise. The temperature was controlled at 65°C, and an interfacial polymerization reaction was carried out under stirring to generate a polyurea capsule wall. The reaction time was 2 hours.

[0060] e. Cooling and post-processing:

[0061] After the reaction was completed, the mixture was cooled to room temperature (25°C), the microcapsules were filtered out, washed with distilled water for several times, and finally dried at 40°C to obtain curing agent microcapsules.

[0062] By using thermoplastic polyurethane elastomer, repair microcapsules and modified polyimide fibers, and limiting the proportion of each component, the three components work together in the composite material. The repair microcapsules can rupture when violently impacted by external sharp objects and quickly fill cracks and gaps. On the one hand, the TPU matrix can quickly fill cracks and gaps at the rupture under dynamic load, buying time for the flow filling and curing of the broken epoxy resin of the microcapsules. On the other hand, its excellent interfacial bonding properties work synergistically with the modified polyimide fibers to provide a stable composite matrix, and fiber reinforcement prevents the generation or extension of secondary cracks.

[0063] Optionally, the method for preparing the second self-repairing layer comprises the following steps:

[0064] S1: Add thermoplastic polyurethane elastomer into a mixer at a temperature of 110-130°C and mix for 5-8 minutes;

[0065] S2: Add the repair microcapsules and modified polyimide fibers evenly into the mixer, control the temperature at 100-120°C, and mix for 20-30 minutes;

[0066] S3: sending the uniformly mixed material into an extruder for extrusion molding, and obtaining the second self-repairing layer after cooling and molding;

[0067] Preferably, the extrusion molding parameters in step S3 are a temperature of 160-180° C. and a pressure of 6-8 MPa.

[0068] Specifically, the preparation method of the modified polyimide fiber (average diameter 5-10 μm, length 3-6 mm) is as follows: repeatedly rinse the polyimide fiber with deionized water until it is neutral, filter and dry it for later use; add deionized water to 50 mL of ethanol and mix them in a volume ratio of (95:5); add silane coupling agent KH550 (mass concentration is 2%), and stir evenly with a magnetic stirrer; adjust the pH value of the solution to 4.5-5.0 (using dilute hydrochloric acid), and let it stand for 30 minutes to complete the hydrolysis.

[0069] Add the polyimide fiber into the above-mentioned silane coupling agent solution in a ratio of 50 mL of solution volume corresponding to 1 g of fiber mass; stir and react in a constant temperature water bath at 70 °C for 2 h, while maintaining slight mechanical stirring to ensure uniform wetting of the fiber. After the reaction is completed, take out the fiber and rinse it repeatedly with ethanol and deionized water to remove the unreacted silane coupling agent. Place the fiber in a vacuum drying oven and dry it at 80 °C for 12 h to obtain the modified polyimide fiber.

[0070] According to another aspect of the present application, there is provided a preparation method of the self-repairing composite material for new energy vehicle tires as described above, including the following steps:

[0071] (1) Sand the bottom surface of the first self-repairing layer and the top surface of the second self-repairing layer, and then clean them with ethanol;

[0072] (2) After it is completely dry, apply the preheated adhesive on the top surface of the second self-repairing layer, then laminate and press the first self-repairing layer and the second self-repairing layer, and obtain the self-repairing composite material for new energy vehicle tires after cooling and curing.

[0073] Specifically, in step (1), sand with 120# sandpaper, in step (2), preheat the adhesive to 125 °C, control the thickness of the adhesive layer at 0.1 mm; the pressure is 0.4 MPa, the temperature is 130 °C, and keep for 8 min.

[0074] According to another aspect of the present application, there is also provided a tire, which sequentially includes a tread layer, a self-repairing composite material layer and a tire inner layer from outside to inside. The self-repairing composite material layer is the self-repairing composite material for new energy vehicle tires as described above or the self-repairing composite material for new energy vehicle tires prepared by the above preparation method. Among them, the first self-repairing layer is arranged close to the tread layer, and the second self-repairing layer is arranged close to the tire inner layer.

[0075] The beneficial effects that can be produced by the present application include but are not limited to:

[0076] 1. The self-repairing composite material for new energy vehicle tires provided by the present application, through the design of the double-layer self-repairing composite material, combines the advantages of the dynamic vulcanized rubber system and the repair microcapsules to achieve the dynamic inhibition and repair of cracks; among them, the functional filler system in the first self-repairing layer provides excellent thermal conductivity and crack inhibition effect, and the repair microcapsules in the second self-repairing layer cooperate with TPU to first fill and block the gap when cracks occur, simultaneously quickly release the core material to complete the curing of the colloid, and finally effectively achieve self-repair at the damaged part. The modified fiber provides stable support, and the overall impact resistance performance is excellent, effectively extending the service life of the tire.

[0077] 2. The self - repairing composite material for new - energy vehicle tires provided by this application, by introducing a combined heat - conducting filler system of modified boron nitride and alumina, can quickly conduct the heat generated during the tire's driving process, reduce heat accumulation, and lower the impact of temperature rise on the performance of the self - repairing material. At the same time, the reasonable proportion of the filler optimizes the mechanical properties of the composite material, enhancing the overall thermal stability and fatigue resistance ability.

[0078] 3. The self - repairing composite material for new - energy vehicle tires provided by this application, the addition of modified polyimide fibers in the second self - repairing layer not only significantly enhances the mechanical properties of the material, but also has good interfacial bonding force, enables the micro - capsules to be effectively dispersed, has good compatibility with the matrix material, ensures the reliability of the self - repairing material under cyclic deformation conditions, and prevents inter - layer peeling and crack propagation. Detailed implementation manners

[0079] The following describes this application in detail with reference to the embodiments, but this application is not limited to these embodiments.

[0080] Unless otherwise defined, all professional and scientific terms used herein have the same meaning as those familiar to persons skilled in the art. The reagents or raw materials used in the present invention can all be obtained through conventional channels. Unless otherwise specified, the reagents or raw materials used in the present invention are used in the conventional manner in the art or in accordance with the product instructions. In addition, any methods and materials similar or equivalent to the described content can be applied to the method of the present invention. The preferred implementation methods and materials described in this patent are only for demonstration purposes.

[0081] The polypropylene, natural rubber, and ethylene - propylene rubber used in this application are all commercially available materials. The physical and chemical parameters of natural rubber are: Mooney viscosity (ML(1 + 4)100℃): 50 - 70, tensile strength ≥20 MPa; the Mooney viscosity of ethylene - propylene rubber (ML(1 + 4)100℃): 30 - 60, ethylene content: 50 - 60 wt%, tensile strength ≥10 MPa. In the following embodiments, the parameters and preparation methods of various substances not described in detail all adopt the content recorded in the specification.

[0082] Example 1: Self - repairing composite material 1#

[0083] The self - repairing composite material 1# is composed of a first self - repairing layer and a second self - repairing layer connected together;

[0084] The first self - repairing layer: calculated by weight parts, the first self - repairing layer is prepared from the following components: 100 parts of a dynamically vulcanized rubber system, 20 parts of a functional filler system, and 5 parts of a vulcanization accelerator; the dynamically vulcanized rubber system includes polypropylene, natural rubber, and ethylene - propylene rubber, and the addition amount of polypropylene in the dynamically vulcanized rubber system is 25%; the functional filler system includes a heat - conducting filler, and the heat - conducting filler includes modified boron nitride and alumina; the vulcanization accelerator includes sulfur and N - cyclohexyl - 2 - benzothiazole sulfenamide.

[0085] Among them, the weight ratio of natural rubber to ethylene - propylene rubber in the dynamically vulcanized rubber system is 2.5:1. The weight ratio of modified boron nitride to alumina in the heat - conducting filler is 2:1; the modified boron nitride includes silane - modified boron nitride and polymer - coated modified boron nitride, and the weight ratio is 1.5:1. The weight ratio of sulfur to N - cyclohexyl - 2 - benzothiazole sulfenamide in the vulcanization accelerator is 1.5:1.

[0086] The preparation method of the first self - repairing layer includes the following steps:

[0087] S1: Add polypropylene, natural rubber, and ethylene - propylene rubber into a kneader, the temperature is 160 °C, and knead for 8 min;

[0088] S2: Then add the vulcanization accelerator, raise the temperature to 175 °C, dynamically knead for 4 min, and then add the functional filler system;

[0089] S3: Continue to knead for 3 min, and then press - form through an open mill to obtain the first self - repairing layer; in step S3, the pressure for open - mill forming is 11 MPa, the temperature is 165 °C, and the time is 9 min.

[0090] The second self - repairing layer: calculated by weight parts, the second self - repairing layer is prepared from the following components: 105 parts of thermoplastic polyurethane elastomer, 30 - 40 parts of repair micro - capsules, and 12 parts of modified polyimide fiber; the repair micro - capsules are composed of a core material and a capsule wall, and the core material is an epoxy resin mixture or a curing agent mixture.

[0091] The repair micro - capsules include type A micro - capsules and type B micro - capsules, and the weight ratio is 1.3:1; type A micro - capsules are epoxy resin micro - capsules, the core material is DGEBA epoxy resin and dibutylhydroxytoluene, and the weight ratio is 65:1, and the capsule wall is polymethyl methacrylate; type B micro - capsules are curing agent micro - capsules, the core material is tetraethylenepentamine and dibutylhydroxytoluene, and the weight ratio is 60:1, and the capsule wall is polyurea.

[0092] The preparation method of the second self - repairing layer includes the following steps:

[0093] S1: Add thermoplastic polyurethane elastomer into a kneader, the temperature is 120 °C, and knead for 6 min;

[0094] S2: Then, uniformly add the repair microcapsules and the modified polyimide fibers into a kneader, control the temperature at 110°C, and knead for 25 min;

[0095] S3: Feed the uniformly kneaded material into an extruder for extrusion molding. After cooling and molding, the second self - repairing layer is obtained. The extrusion molding parameters in step S3 are a temperature of 170°C and a pressure of 7 MPa.

[0096] A preparation method of self - repairing composite material 1# includes the following steps:

[0097] (1) Sand the bottom surface of the first self - repairing layer and the top surface of the second self - repairing layer with sandpaper, and then clean them with ethanol;

[0098] (2) After complete drying, coat the pre - heated adhesive on the top surface of the second self - repairing layer, then bond and press the first self - repairing layer and the second self - repairing layer together. After cooling and curing, the self - repairing composite material 1# for new energy vehicle tires is obtained.

[0099] Among them, in step (1), sand with 120# sandpaper. In step (2), pre - heat the adhesive to 125°C, control the adhesive layer thickness at 0.1 mm; the pressure is 0.4 MPa, the temperature is 130°C, and keep for 8 min.

[0100] Example 2: Self - repairing composite material 2#

[0101] The self - repairing composite material 2# is composed of a connection of a first self - repairing layer and a second self - repairing layer;

[0102] The first self - repairing layer: By weight, the first self - repairing layer is prepared from the following components: 80 parts of a dynamically vulcanized rubber system, 18 parts of a functional filler system, and 3 parts of a vulcanization accelerator; the dynamically vulcanized rubber system includes polypropylene, natural rubber, and ethylene - propylene rubber, and the addition amount of polypropylene in the dynamically vulcanized rubber system is 30%; the functional filler system includes heat - conducting fillers, and the heat - conducting fillers include modified boron nitride and alumina; the vulcanization accelerator includes sulfur and N - cyclohexyl - 2 - benzothiazole sulfenamide.

[0103] Among them, the weight ratio of natural rubber to ethylene - propylene rubber in the dynamically vulcanized rubber system is 2:1. The weight ratio of modified boron nitride to alumina in the heat - conducting filler is 2:1; the modified boron nitride includes silane - modified boron nitride and polymer - coated modified boron nitride, and the weight ratio is 1.5:1. The weight ratio of sulfur to N - cyclohexyl - 2 - benzothiazole sulfenamide in the vulcanization accelerator is 1:1.

[0104] The preparation method of the first self - repairing layer includes the following steps:

[0105] S1: Add polypropylene, natural rubber, and ethylene - propylene rubber into a Banbury mixer, the temperature is 155°C, and knead for 10 min;

[0106] S2: Then add vulcanization accelerator, heat up to 170 °C, conduct dynamic mixing for 5 min, and then add the functional filler system.

[0107] S3: After continuing to mix for 4 min, press and form through a mill to obtain the first self - repairing layer. In step S3, the pressure for pressing and forming is 10 MPa, the temperature is 160 °C, and the time is 10 min.

[0108] The second self - repairing layer: By weight, the second self - repairing layer is prepared from the following components: 100 parts of thermoplastic polyurethane elastomer, 30 parts of repair microcapsules, and 10 parts of modified polyimide fiber; the repair microcapsules are composed of a core material and a capsule wall, and the core material is an epoxy resin mixture or a curing agent mixture.

[0109] The repair microcapsules include type A microcapsules and type B microcapsules, and the weight ratio is 1.2:1; type A microcapsules are epoxy resin microcapsules, the core material is DGEBA epoxy resin and dibutylhydroxytoluene, and the weight ratio is 60:1, and the capsule wall is polymethyl methacrylate; type B microcapsules are curing agent microcapsules, the core material is tetraethylenepentamine and dibutylhydroxytoluene, and the weight ratio is 55:1, and the capsule wall is polyurea.

[0110] The preparation method of the second self - repairing layer includes the following steps:

[0111] S1: Add thermoplastic polyurethane elastomer into a mixer, the temperature is 110 °C, and mix for 8 min.

[0112] S2: Then evenly add the repair microcapsules and modified polyimide fiber into the mixer, control the temperature at 100 °C, and mix for 30 min.

[0113] S3: Feed the uniformly mixed material into an extruder for extrusion molding, and obtain the second self - repairing layer after cooling and forming. In step S3, the extrusion molding parameters are a temperature of 160 °C and a pressure of 8 MPa.

[0114] The preparation method of the self - repairing composite material 2# includes the following steps:

[0115] (1) Sand the bottom surface of the first self - repairing layer and the top surface of the second self - repairing layer, and then clean them with ethanol.

[0116] (2) After being completely dry, coat the pre - heated adhesive on the top surface of the second self - repairing layer, then laminate and press the first self - repairing layer and the second self - repairing layer, and obtain the self - repairing composite material 2# for new energy vehicle tires after cooling and curing.

[0117] Among them, in step (1), it is polished with 120# sandpaper. In step (2), the adhesive is preheated to 125 °C, the thickness of the adhesive layer is controlled at 0.1 mm; the pressure is 0.4 MPa, the temperature is 130 °C, and it is maintained for 8 min.

[0118] Example 3 Self-healing Composite Material 3#

[0119] The self-healing composite material 3# is composed of a first self-healing layer and a second self-healing layer connected together;

[0120] First self-healing layer: By weight, the first self-healing layer is prepared from the following components: 120 parts of a dynamically vulcanized rubber system, 35 parts of a functional filler system, and 8 parts of a vulcanization accelerator; the dynamically vulcanized rubber system includes polypropylene, natural rubber, and ethylene-propylene rubber, and the addition amount of polypropylene in the dynamically vulcanized rubber system is 15%; the functional filler system includes a heat-conducting filler, and the heat-conducting filler includes modified boron nitride and alumina; the vulcanization accelerator includes sulfur and N-cyclohexyl-2-benzothiazole sulfenamide.

[0121] Among them, the weight ratio of natural rubber to ethylene-propylene rubber in the dynamically vulcanized rubber system is 3:1. The weight ratio of modified boron nitride to alumina in the heat-conducting filler is 3:1; the modified boron nitride includes silane-modified boron nitride and polymer-coated modified boron nitride, and the weight ratio is 2:1. The weight ratio of sulfur to N-cyclohexyl-2-benzothiazole sulfenamide in the vulcanization accelerator is 1.5:1.

[0122] The preparation method of the first self-healing layer includes the following steps:

[0123] S1: Add polypropylene, natural rubber, and ethylene-propylene rubber to an internal mixer, the temperature is 165 °C, and mix for 5 min;

[0124] S2: Then add the vulcanization accelerator, raise the temperature to 180 °C, dynamically mix for 3 min and then add the functional filler system;

[0125] S3: Continue to mix for 4 min, and then press and form through a two-roll mill to obtain the first self-healing layer;

[0126] Preferably, in step S3, the pressure for open-mold forming is 12 MPa, the temperature is 160 °C, and the time is 9 min.

[0127] Second self-healing layer: By weight, the second self-healing layer is prepared from the following components: 110 parts of thermoplastic polyurethane elastomer, 40 parts of repair microcapsules, and 15 parts of modified polyimide fiber; the repair microcapsules are composed of a core material and a capsule wall, and the core material is an epoxy resin mixture or a curing agent mixture.

[0128] The self - repairing microcapsules include type A microcapsules and type B microcapsules, with a weight ratio of 1.4:1; type A microcapsules are epoxy resin microcapsules, the core material is DGEBA epoxy resin and dibutylhydroxytoluene, with a weight ratio of 70:1, and the capsule wall is polymethyl methacrylate; type B microcapsules are curing agent microcapsules, the core material is tetraethylenepentamine and dibutylhydroxytoluene, with a weight ratio of 65:1, and the capsule wall is polyurea.

[0129] The preparation method of the second self - repairing layer includes the following steps:

[0130] S1: Add thermoplastic polyurethane elastomer into a mixer, the temperature is 130 °C, and mix for 5 min;

[0131] S2: Then evenly add the self - repairing microcapsules and modified polyimide fibers into the mixer, control the temperature at 120 °C, and mix for 20 min;

[0132] S3: Feed the uniformly mixed material into an extruder for extrusion molding. After cooling and molding, the second self - repairing layer is obtained; the extrusion molding parameters in step S3 are a temperature of 180 °C and a pressure of 6 MPa.

[0133] The preparation method of the self - repairing composite material 3# includes the following steps:

[0134] (1) Sand the bottom surface of the first self - repairing layer and the top surface of the second self - repairing layer with sandpaper, and then clean them with ethanol;

[0135] (2) After it is completely dry, coat the pre - heated adhesive on the top surface of the second self - repairing layer, then laminate and press the first self - repairing layer and the second self - repairing layer. After cooling and curing, the self - repairing composite material 3# for new energy vehicle tires is obtained.

[0136] Among them, in step (1), it is sanded with 120# sandpaper. In step (2), the adhesive is pre - heated to 125 °C, the thickness of the adhesive layer is controlled at 0.1 mm; the pressure is 0.4 MPa, the temperature is 130 °C, and it is maintained for 8 min.

[0137] Example 4: Self - repairing composite material 4#

[0138] The difference between Example 4 and Example 1 is that: in Example 4, the functional filler system also includes crack - inhibiting fillers and dynamic reinforcing fillers; the thermal conductive filler, crack - inhibiting filler and dynamic reinforcing filler have a weight ratio of 8:3:3 in sequence; the crack - inhibiting filler is silane - modified nano - silicon micropowder, and the dynamic reinforcing filler is nano - cerium oxide.

[0139] Example 5: Self - repairing composite material 5#

[0140] The difference between Example 5 and Example 1 is that: in Example 5, only silane - modified boron nitride is used, and polymer - coated modified boron nitride is not used.

[0141] Comparative Example 1: Comparing Self - Repairing Composite Material 1#

[0142] The difference between Comparative Example 1 and Example 1 is that in Comparative Example 1, the first self - repairing layer uses a rubber system composed of natural rubber and ethylene - propylene rubber without dynamic vulcanization.

[0143] Comparative Example 2: Comparing Self - Repairing Composite Material 2#

[0144] The difference between Comparative Example 2 and Example 1 is that in Comparative Example 2, the addition amount of polypropylene is 45%.

[0145] Comparative Example 3: Comparing Self - Repairing Composite Material 3#

[0146] The difference between Comparative Example 3 and Example 1 is that in Comparative Example 3, the thermal conductive fillers use unmodified boron nitride and alumina.

[0147] Comparative Example 4: Comparing Self - Repairing Composite Material 4#

[0148] The difference between Comparative Example 4 and Example 1 is that in Comparative Example 4, the second self - repairing layer does not use modified polyimide fibers.

[0149] Experimental Example

[0150] The self - repairing composite materials prepared in Examples 1 - 5 and Comparative Examples 1 - 4 were respectively subjected to the following experimental tests:

[0151] 1. Thermal stability test: The test was carried out according to the ISO 188:2011 standard. After high - temperature aging, the initial mass and the mass after aging of the samples were compared, and the mass loss rate was calculated. The lower the mass loss rate, the better the thermal stability of the sample. Mass loss rate = ((Initial mass - Final mass) / Initial mass)×100%.

[0152] 2. Dynamic compression fatigue resistance performance test

[0153] Reference standard: ASTM D575 (Rubber Compression Performance Test)

[0154] Purpose: To determine the fatigue performance of the composite material under dynamic compression conditions.

[0155] Method: Specimen size: 10mm×10mm×10mm; Apply periodic compressive stress (frequency 5Hz, maximum strain 30%). Record the final failure cycle number of the specimen. To be closer to the real situation, it is recorded in 10 times, and rounded to the nearest integer for statistics. The larger the number, the better the fatigue resistance performance.

[0156] 3. Impact resistance test

[0157] Refer to GB / T 1043-2008 (Izod impact test), and record the impact strength.

[0158] 4. Repair performance test

[0159] Add the self-healing composites prepared in Examples 1-5 and Comparative Examples 1-4 to prepare corresponding tires according to the conventional tire manufacturing process, and test the repair ability.

[0160] The experimental conditions are as follows:

[0161] a. Tire pretreatment: Apply the self-healing layers made of the composite materials of the examples and comparative examples to the interlayers of tires of the same model respectively, and use a pressure sensor to record the initial inflation pressure (2.5 bar).

[0162] b. Leakage simulation: Use the tip of a Phillips head awl to create 2 damaged holes with different diameters and shapes on different positions of the tire surface [about 2.0 mm, 3.0 mm (with cracks at the edge)]. Mark the edge area of each damaged part for subsequent observation and data recording.

[0163] c. Repair process test:

[0164] Apply a single-wheel equivalent load (300 kg) on the tire testing machine, and the drum speed simulates the speed of driving at 80 km / h. Record the internal pressure of the tire after 30 minutes.

[0165] d. Data recording:

[0166] Repair efficiency = repaired pressure value / initial pressure value × 100%, rounded to the nearest integer.

[0167] The test results of each experiment are shown in Table 1.

[0168] Table 1 Performance tests of the self-healing composites prepared in Examples 1-5 and Comparative Examples 1-4

[0169]

[0170] From the above results, it can be seen that the self-healing composites prepared by using the components and methods defined in the present application have excellent heat resistance, fatigue resistance, impact resistance and repair ability. The mass loss rates of Examples 1-4 are all less than 1%, the final failure times in the dynamic fatigue test are relatively high, the impact resistance strengths are all above 60 J, and the repair efficiencies are all above 90%, indicating that the repair effects on different types of irregular damages or cracks are all good, and the comprehensive performance is excellent.

[0171] Each embodiment in this specification is described in a progressive manner. For the identical or similar parts among the embodiments, they can be referred to each other. Each embodiment focuses on the differences from other embodiments. In particular, for the system embodiment, since it is basically similar to the method embodiment, it is described relatively simply, and the relevant parts can be referred to the partial description of the method embodiment.

[0172] The above are only the embodiments of the present application and are not intended to limit the present application. For those skilled in the art, various changes and modifications can be made to the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included within the scope of the claims of the present application.

Claims

1. A self-repairing composite material for new energy vehicle tires, characterized in that, It is composed of a first self-repairing layer and a second self-repairing layer connected together; By weight parts, the first self-repairing layer is prepared from the following components: 80-120 parts of a dynamically vulcanized rubber system, 18-35 parts of a functional filler system, and 3-8 parts of a vulcanization accelerator; the dynamically vulcanized rubber system includes polypropylene, natural rubber, and ethylene-propylene rubber, and the addition amount of polypropylene in the dynamically vulcanized rubber system does not exceed 30%; the functional filler system includes a heat-conducting filler, and the heat-conducting filler includes modified boron nitride and alumina; the vulcanization accelerator includes sulfur and N-cyclohexyl-2-benzothiazole sulfenamide; By weight parts, the second self-repairing layer is prepared from the following components: 100-110 parts of thermoplastic polyurethane elastomer, 30-40 parts of repair microcapsules, and 10-15 parts of modified polyimide fiber; the repair microcapsules are composed of a core material and a capsule wall, and the core material is an epoxy resin mixture or a curing agent mixture.

2. The self-repairing composite material for new energy vehicle tires according to claim 1, characterized in that, In the dynamically vulcanized rubber system, the weight ratio of natural rubber to ethylene-propylene rubber is (2-3):

1.

3. The self-repairing composite material for new energy vehicle tires according to claim 1, wherein, In the heat-conducting filler, the weight ratio of modified boron nitride to alumina is (2-3):1; The modified boron nitride includes silane-modified boron nitride and polymer-coated modified boron nitride, and the weight ratio is (1.5-2):

1.

4. The self-repairing composite material for new energy vehicle tires according to claim 1, characterized in that, The functional filler system further includes a crack suppression filler and a dynamic reinforcement filler; The weight ratio of the heat-conducting filler, the crack suppression filler, and the dynamic reinforcement filler is (6-12):(3-7):(2-5) in sequence.

5. The self-repairing composite material for new energy vehicle tires according to claim 4, characterized in that, The crack suppression filler is silane-modified nano-silica powder, and the dynamic reinforcement filler is nano-ceria.

6. The self-repairing composite material for new energy vehicle tires according to claim 1, characterized in that, In the vulcanization accelerator, the weight ratio of sulfur to N-cyclohexyl-2-benzothiazole sulfenamide is (1-1.5):

1.

7. The self-repairing composite material for new energy vehicle tires according to claim 1, wherein The preparation method of the first self-repairing layer includes the following steps: S1: Add polypropylene, natural rubber, and ethylene-propylene rubber into a mixer, with the temperature being 155-165°C, and knead for 5-10 min; S2: Then add the vulcanization accelerator, raise the temperature to 170-180°C, dynamically knead for 3-5 min, and then add the functional filler system; S3: Continue to knead for 2-4 min, and then press and form through a two-roll mill to obtain the first self-repairing layer.

8. The self-repairing composite material for new energy vehicle tires according to claim 7, wherein, In step S3, the pressure for press forming is 10-12 MPa, the temperature is 160-165°C, and the time is 8-10 min.

9. The self-repairing composite material for new energy vehicle tires according to claim 1, characterized in that, The repair microcapsules include type A microcapsules and type B microcapsules, and the weight ratio is (1.2-1.4):1; The type A microcapsules are epoxy resin microcapsules, the core material is DGEBA epoxy resin and dibutylhydroxytoluene, and the weight ratio is (60-70):1, and the capsule wall is polymethyl methacrylate; The type B microcapsules are curing agent microcapsules, the core material is tetraethylenepentamine and dibutylhydroxytoluene, and the weight ratio is (55-65):1, and the capsule wall is polyurea.

10. The self-repairing composite material for new energy vehicle tires according to claim 1, characterized in that, The preparation method of the second self-repairing layer includes the following steps: S1: Add the thermoplastic polyurethane elastomer into a kneader, with the temperature being 110-130°C, and knead for 5-8 min; S2: Then, uniformly add the repair microcapsules and the modified polyimide fibers into a mixer, control the temperature at 100 - 120 °C, and knead for 20 - 30 min; S3: Feed the uniformly kneaded material into an extruder for extrusion molding. After cooling and molding, the second self - repairing layer is obtained.

11. The self-repairing composite material for new energy vehicle tires according to claim 10, wherein, In step S3, the extrusion molding parameters are a temperature of 160 - 180 °C and a pressure of 6 - 8 MPa.

12. A method for preparing a self-repairing composite material for new energy vehicle tires as described in any one of claims 1-11, characterized in that, It includes the following steps: (1) Sand the bottom surface of the first self - repairing layer and the top surface of the second self - repairing layer, and then clean them with ethanol; (2) After being completely dry, apply the pre - heated adhesive on the top surface of the second self - repairing layer, then bond and press the first self - repairing layer and the second self - repairing layer together. After cooling and curing, the self - repairing composite material for new energy vehicle tires is obtained.

13. A tire, which sequentially includes a tread layer, a self-repairing composite material layer, and a carcass layer from outside to inside, is characterized in that The self - repairing composite material layer is the self - repairing composite material for new energy vehicle tires as described in any one of claims 1 - 11 or the self - repairing composite material for new energy vehicle tires prepared by the preparation method in claim 12, wherein the first self - repairing layer is arranged close to the tread layer, and the second self - repairing layer is arranged close to the inner tire layer.

Images