A high polymer composite material for a run-flat tire and a method for manufacturing the same

Abstract

The application discloses a kind of high molecular composite material for non-inflatable tire and preparation method thereof, belong to high molecular composite material and polyurethane elastomer preparation technical field.The high molecular composite material is composed of polycaprolactone diol PCL1000, polycaprolactone diol PCL2000, MDI-100 isocyanate, butanediol BDO, multi-walled carbon nanotube, white carbon black, polytetrafluoroethylene PTFE micro powder, antioxidant, ultraviolet absorber, epoxy resin stabilizer, plasticizer, KH550 coupling agent, defoaming agent and release agent.The preparation method includes polycaprolactone diol vacuum dehydration, nano-reinforced filler pre-dispersion, polyurethane prepolymer preparation, chain extension reaction, vacuum defoaming, pouring mould pressing and curing demoulding and the like steps.By constructing polycaprolactone double soft segment system and multi-walled carbon nanotube, white carbon black and PTFE micro powder synergistic reinforcing system, and combining coupling agent to improve interface bonding performance, the obtained polyurethane composite material has excellent tensile strength, wear resistance, high temperature aging resistance and dimensional stability.

Description

Technical Field

[0001] This invention relates to the field of polymer composite materials and polyurethane elastomer preparation technology, specifically to a polymer composite material for pneumatic tires and its preparation method. Background Technology

[0002] With the continuous advancement of green manufacturing and low-carbon travel concepts, pneumatic tires have gradually been widely used in electric vehicles, personal mobility vehicles, industrial transport vehicles, and special equipment due to their advantages such as no need for inflation, no risk of tire blowout, puncture resistance, low maintenance costs, and long service life.

[0003] Currently, most pneumatic tires on the market are made from vulcanized rubber systems such as natural rubber, styrene-butadiene rubber, and cis-butadiene rubber. Although these materials have good elasticity and cushioning performance during long-term use, they still have the following problems: (1) Poor environmental performance. After vulcanization, traditional rubber systems form a stable three-dimensional cross-linked network structure. Waste tires are difficult to remelt and process, and recycling is difficult. They are usually disposed of by incineration or landfill, which easily leads to resource waste and environmental pollution. (2) Insufficient weight reduction. In order to meet the tire load-bearing performance requirements, existing pneumatic tires usually need to add a high proportion of high-density reinforcing components such as carbon black and mineral fillers, which leads to an increase in the overall weight of the tire, thereby increasing the rolling resistance and operating energy consumption of the vehicle. (3) It is difficult to achieve both wear resistance and weather resistance. Although the high elasticity polymer system has good shock absorption performance, it is not wear-resistant. On the other hand, improving wear resistance often leads to an increase in material rigidity, which affects driving comfort. (4) The processing stability needs to be improved. Nano-reinforced materials are prone to agglomeration in polyurethane systems, resulting in uneven internal structure of the material, which affects the mechanical properties and service life of the final product. Therefore, developing a polymer composite material for pneumatic tires that combines high strength, high wear resistance, excellent weather resistance, lightweight and recyclability is of great significance for promoting the development of the green tire industry. Summary of the Invention

[0004] The purpose of this invention is to provide a polymer composite material for pneumatic tires and its preparation method, so as to solve the technical problems of existing pneumatic tires, such as high weight, high rolling resistance, high energy consumption, difficulty in recycling, and insufficient wear resistance and weather resistance. Under the premise of ensuring tire load-bearing capacity and driving comfort, the invention achieves tire lightweighting, long service life and green environmental protection.

[0005] To achieve the above objectives, the present invention provides the following technical solution: a polymer composite material for pneumatic tires, wherein the raw materials, by mass parts, include: 55-65 parts polycaprolactone diol PCL1000, 35-45 parts polycaprolactone diol PCL2000, 45-50 parts isocyanate MDI-100, 5-10 parts butanediol BDO, 0.5-1.5 parts multi-walled carbon nanotubes, 3.5-4.5 parts silica, and 1.2-1.8 parts polytetrafluoroethylene (PTFE). The composition includes PTFE micro powder, 0.3–0.5 parts antioxidant, 0.2–0.4 parts UV absorber UV-531, 0.3–0.5 parts epoxy resin stabilizer, 1.5–2.5 parts plasticizer, 1.8–2.5 parts polyurethane coupling agent, 0.2–0.5 parts defoamer, and 0.2–0.4 parts release agent. Based on a total mass of 100 parts of polycaprolactone diol PCL1000, the remaining components are all parts by mass relative to the 100 parts of polyol. The polycaprolactone diol PCL1000 and polycaprolactone diol PCL2000 together constitute a polyurethane soft segment system, with polycaprolactone diols of different molecular weights forming a gradient of flexible segments. The isocyanate reacts with the polycaprolactone diol to form a polyurethane prepolymer, and the butanediol acts as a chain extender to construct a polyurethane crosslinking network. The multi-walled carbon nanotubes, fumed silica, and polytetrafluoroethylene (PTFE) micropowder together form a ternary synergistic reinforcing network. The multi-walled carbon nanotubes are used to improve the tensile strength and fatigue resistance of the material. The fumed silica is used to improve the reinforcing performance and dimensional stability of the material. The PTFE micropowder is dispersed in the polyurethane matrix to form a self-lubricating phase and together with the multi-walled carbon nanotubes to construct a wear-resistant and friction-reducing network. The plasticizer is selected as dioctyl sebacate (DOS), and the polyurethane coupling agent is selected as aminopropyltriethoxysilane (KH550). The polyurethane coupling agent forms an interfacial coupling layer with the hydroxyl groups on the surface of multi-walled carbon nanotubes, the silanol groups on the surface of silica, and the polyurethane matrix, so that the ternary synergistic reinforcing network is uniformly distributed in the continuous polyurethane phase. The antioxidant, ultraviolet absorber, and epoxy resin stabilizer together form an aging-resistant and stable system.

[0006] Furthermore, the present invention also provides a method for preparing the above-mentioned polymer composite material, comprising the following steps: S1. After mixing PCL1000 and PCL2000, vacuum dehydration treatment is carried out to form a uniform dual-soft-segment polyurethane soft-segment system. S2. Using partially dehydrated polycaprolactone as a dispersion medium, multi-walled carbon nanotubes, silica, polytetrafluoroethylene powder and KH550 coupling agent are dispersed by high-speed shearing, so that KH550 forms an interfacial coupling layer on the surface of each nanofiller, and a stable dispersed ternary reinforced slurry is obtained. S3. The ternary reinforced slurry is mixed with the remaining polycaprolactone and then added to MDI-100 for prepolymerization to form a polyurethane prepolymer containing a uniform reinforcing phase. S4. Add butanediol chain extender, antioxidant, ultraviolet absorber, epoxy stabilizer, DOS plasticizer, defoamer and release agent to the polyurethane prepolymer, and form a uniform casting system after chain extension, mixing and vacuum degassing. S5. The casting system is injected into a preheated mold and molded and cured at 95-105°C and 8-12MPa for 30-40 minutes, and then cured for another 2-3 hours to allow the polyurethane continuous phase, ternary synergistic reinforcing phase and self-lubricating phase to form an interpenetrating reinforcing structure, thereby obtaining a polymer composite material for pneumatic tires. S8. The material is cooled and demolded to obtain a polymer composite material product for pneumatic tires.

[0007] In summary, the beneficial technical effects of the present invention are as follows: Excellent mechanical properties: A dual-soft-segment polyurethane system is constructed using polycaprolactone diol (PCL1000) and PCL2000. Polycaprolactone diols of different molecular weights form gradient flexible segments in the polyurethane network. PCL1000 provides high segment regularity and support capacity, while PCL2000 provides good flexibility and resilience. The two work synergistically to form a network structure in the continuous polyurethane phase that combines high strength, high elasticity, and high fatigue resistance. The tensile strength and tear strength are increased by about 25% to 35% compared to the traditional polycaprolactone polyurethane system. The hardness adjustment range is wide, which can meet the application requirements of different pneumatic tires.

[0008] Outstanding wear resistance: A ternary synergistic reinforcement system is constructed using multi-walled carbon nanotubes, silica, and polytetrafluoroethylene (PTFE) micropowder. Multi-walled carbon nanotubes form a nano-reinforcing skeleton, improving the tensile strength and fatigue resistance of the polyurethane matrix. Silica improves the material modulus and dimensional stability through particle reinforcement. PTFE micropowder migrates to the friction interface to form a solid lubricating film, and the interwoven network of multi-walled carbon nanotubes inhibits matrix tearing. The two work synergistically to reduce DIN wear volume, improving wear resistance by more than 40% compared to pure PU.

[0009] Excellent weather resistance: An aging-resistant and stable system is constructed using antioxidants, UV absorber UV-531, and epoxy resin stabilizers. This system effectively inhibits molecular chain breakage and cross-linking degradation of polyurethane materials during thermal oxidation, ultraviolet radiation, and long-term environmental aging. It improves the retention rate of mechanical properties and dimensional stability of the material after hot air aging, allowing the material to maintain high mechanical properties even after long-term ultraviolet irradiation. There is no obvious yellowing after 1000 hours of ultraviolet aging, and the high-temperature aging performance is significantly improved.

[0010] Excellent processing performance: The preparation process combines stepwise dehydration of polycaprolactone, pre-dispersion of nanofillers, prepolymerization reaction, chain extension reaction, vacuum degassing, molding curing and aging, which enables the nanofillers to be uniformly and stably dispersed in the polyurethane system. At the same time, it effectively removes moisture and bubbles from the system, reduces defects such as internal porosity, shrinkage cavities, delamination and filler agglomeration in the product, improves the dimensional consistency and batch stability of the product, and improves the fluidity of the system by combining a reasonable additive system, reducing bubble defects and making it easy to demold. It is suitable for casting and compression molding processes. Attached Figure Description

[0011] The accompanying drawings are provided to further illustrate the invention and form part of the specification, but do not constitute a limitation thereof. In the drawings: Figure 1 This is a flowchart of the preparation process of the present invention; Figure 2 This is a flow chart of the polymer composite material preparation process for the pneumatic tires of this invention; Figure 3 The mechanical property test results are for Examples 1 to 3; Figure 4 The results are the wear resistance test results for Examples 1 to 3; Figure 5 The results of high-temperature aging resistance tests for Examples 1 to 3 are as follows; Figure 6 This is a table of test data for the dynamic service performance and recyclability of the composite materials in Examples 1 to 3. Detailed Implementation

[0012] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be noted that these embodiments are only used to explain the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. Various equivalent substitutions, combination optimizations, or conventional improvements made by those skilled in the art to the present invention without departing from the technical concept and the scope of protection defined by the claims should fall within the scope of protection of the present invention. The raw materials used in the following embodiments are all commercially available industrial-grade products; unless otherwise specified, all components are expressed in parts by weight, and all process conditions are completed using conventional industrial production equipment.

[0013] Please see Figure 1-2This invention provides a polymer composite material for pneumatic tires and its preparation method. By constructing a polyurethane nanocomposite material with polycaprolactone diol as the main soft segment, MDI as the isocyanate hard segment, and multi-walled carbon nanotubes, fumed silica, and PTFE micro powder as synergistic reinforcement system, a balance is achieved between lightweight, high strength, high wear resistance, and excellent weather resistance, thereby meeting the requirements of pneumatic tires for load-bearing capacity, cushioning performance, fatigue resistance, and long-term service stability.

[0014] The polymer composite material used in this invention is composed of polycaprolactone diol PCL1000, polycaprolactone diol PCL2000, MDI-100, butanediol BDO, multi-walled carbon nanotubes, silica, polytetrafluoroethylene (PTFE) micro powder, antioxidant, UV absorber UV-531, epoxy resin stabilizer, dioctyl sebacate (DOS), KH550 coupling agent, defoamer, and release agent.

[0015] PCL1000 and PCL2000 together constitute the polyurethane soft segment system. By compounding polycaprolactone diols of different molecular weights, the flexibility, fatigue resistance, and low-temperature performance of the material are improved. MDI-100, as an isocyanate component, reacts with polycaprolactone diol to form a polyurethane prepolymer. BDO, as a chain extender, further forms the polyurethane network structure. Multi-walled carbon nanotubes, silica, and PTFE micropowder form a synergistic reinforcement system, improving the mechanical properties of the material while enhancing its wear resistance and friction reduction properties. KH550 coupling agent is used to enhance the interfacial bonding between the nanofiller and the polyurethane matrix, improving the uniformity of filler dispersion and the interfacial bonding strength. Antioxidant, UV absorber UV-531, and epoxy resin stabilizer together constitute an aging-resistant and stable system, improving the long-term service performance of the material. DOS is used to improve the system's flexibility and processing fluidity. Defoamer is used to reduce bubbles generated during processing. Release agent is used to improve the release performance of the product.

[0016] In the preparation process of this invention, polycaprolactone diol is first subjected to vacuum dehydration to fully remove free water from the system and avoid side reactions between isocyanate and water that could affect the quality of polyurethane polymerization. Then, a portion of the dehydrated polycaprolactone is used as a nanofiller dispersion carrier. Multi-walled carbon nanotubes, silica, PTFE powder, and KH550 coupling agent are fully dispersed using a high-speed shearing device or a three-roll mill to obtain a uniform and stable filler mother liquor. This mother liquor is then thoroughly mixed with the remaining polycaprolactone to ensure uniform distribution of the nanofiller throughout the polyurethane system, reduce agglomeration, and improve the overall performance of the composite material.

[0017] Subsequently, the above-mentioned mixture was prepolymerized with MDI-100. Air and residual moisture were removed by vacuum nitrogen-filled circulation, and the polyurethane prepolymer was prepared in an anhydrous and oxygen-free environment. After the prepolymerization reaction, the prepolymer was cooled to the specified temperature, and the catalyst, BDO chain extender and other additives were added. The mixture was stirred at high speed to ensure that the system was fully mixed and the chain extension reaction was completed. Then, vacuum degassing was performed immediately to remove air bubbles entrained during the mixing process, ensuring that the internal structure of the product was uniform and dense. Finally, the degassed material was poured into a preheated mold and molded under the specified molding temperature, pressure and holding time. After mold curing, room temperature cooling and demolding, the polymer composite material product for pneumatic tires was finally obtained.

[0018] Explanation of prepolymer chain extension coefficient calculation: This invention uses PCL1000 with a hydroxyl value of 112 mg KOH / g; PCL2000 with a hydroxyl value of 56 mg KOH / g; MDI-100, pure 4,4'-MDI; and NCO with a mass fraction of 33.6%. The chain extension coefficient f = total NCO moles / total hydroxyl moles = 0.95. The crosslinking density is controlled by precisely measuring the amount of BDO added, thus balancing the material's elasticity, strength, and wear resistance. BDO addition amount calculation formula:

[0019] Example 1

[0020] Raw material composition The polymer composite material used in this embodiment is composed of the following raw materials in parts by weight: 60 parts polycaprolactone diol PCL1000, 40 parts polycaprolactone diol PCL2000, 47.0 parts MDI-100 isocyanate, 7.0 parts butanediol BDO, 0.8 parts multi-walled carbon nanotubes, 3.6 parts silica, 1.3 parts polytetrafluoroethylene (PTFE) micro powder, 0.3 parts antioxidant, 0.2 parts ultraviolet absorber UV-531, 0.3 parts epoxy resin stabilizer, 2.2 parts dioctyl sebacate (DOS), 1.9 parts KH550 coupling agent, 0.3 parts defoamer, and 0.2 parts release agent.

[0021] (II) Preparation method S101: Weigh PCL1000 (60 parts) and PCL2000 (40 parts) according to the above ratio, add them into the glass reactor, and add 1% of the total mass of polycaprolactone as a dehydrating agent at the same time. Turn on the mechanical stirrer and control the stirring speed at 100 r / min to ensure that the dehydrating agent and polycaprolactone are fully mixed. Then slowly raise the temperature to 110℃ and start the vacuum system to maintain the vacuum degree in the reactor at ≤-0.095MPa. Dehydrate under constant temperature vacuum at 110℃ for 2 hours to fully remove free water and adsorbed water from polycaprolactone, prevent side reactions of isocyanate in the subsequent reaction, and improve the polymerization efficiency of polyurethane and the final material properties. After dehydration, 25% of the total mass of dehydrated polycaprolactone is used as a pre-dispersion carrier for nanofillers, and the remaining 75% is kept warm for later use.

[0022] S102: Add the above 25% dehydrated polycaprolactone to a high-speed shear dispersion device, and then add multi-walled carbon nanotubes, fumed silica, PTFE powder and KH550 coupling agent in sequence. Start the high-speed shearing machine and control the shearing speed at 3500 r / min to continuously shear and disperse the mixture, so that each nanofiller is fully wetted, depolymerized and uniformly dispersed in polycaprolactone. Continue shearing until the material fineness is ≤20μm to obtain a uniform and stable filler mother liquor. Then, the filler mother liquor is thoroughly mixed with the remaining 75% of polycaprolactone to ensure that the nanofillers are evenly distributed in the entire polycaprolactone system, providing a uniform and stable raw material system for the subsequent polyurethane prepolymerization reaction.

[0023] S103: Add the above-mixed polycaprolactone system back into the reactor, heat to 50°C, and add MDI-100 after the polycaprolactone has completely melted. Subsequently, the system was circulated under vacuum and nitrogen twice to fully remove air and residual moisture, creating an anhydrous and oxygen-free reaction environment. The reaction temperature was adjusted to 80°C, and the stirring speed was controlled at 300 r / min. The reaction was carried out at 80°C for 2 hours to allow polycaprolactone diol and MDI to fully undergo a prepolymerization reaction to form a polyurethane prepolymer. After the reaction was completed, the heating system was turned off, and the prepolymer was slowly cooled to 50°C under sealed conditions for later use.

[0024] S104: Take the polyurethane prepolymer prepared above, add 0.05% of the total mass of the prepolymer with an organic bismuth catalyst and 0.5% with a non-silicone defoamer; Butylene glycol (BDO) was added according to a chain extension coefficient f = 0.95, followed by antioxidant, UV absorber UV-531, epoxy resin stabilizer, DOS plasticizer, and other additives. The high-speed stirring equipment was started, and the stirring speed was controlled at 2000 r / min. The mixture was stirred at high speed for 90 seconds to ensure that the chain extender and additives were fully and evenly dispersed until there was no unreacted BDO residue in the system, forming a uniformly flowing polyurethane casting system.

[0025] S105: Quickly transfer the above-mentioned uniformly mixed material to a vacuum degassing device, control the vacuum degree to be less than -0.095MPa, and degas for 5 minutes under constant temperature conditions. During the degassing process, continuously observe the liquid surface state. When the liquid surface tends to be flat and no continuous bubbles rise, end the degassing operation to ensure that there are no obvious bubble defects inside the material during the subsequent casting process and improve the density of the final product.

[0026] S106: Preheat the mold to 95℃ and spray the external release agent evenly on the surface of the mold cavity. Then pour the degassed polyurethane material into the mold at a uniform speed to avoid air entrapment. After pouring, close the mold. Control the molding temperature to 95℃ and the molding pressure to 8MPa, and maintain constant temperature and pressure for 40 minutes to allow the polyurethane system to complete cross-linking, curing and molding.

[0027] S107: After molding, keep the mold closed and heat-curing in the mold for 2 hours to further complete the polyurethane crosslinking reaction, improve the internal structural stability and dimensional stability of the material, and then slowly depressurize and cool naturally at room temperature; when the mold temperature drops below 40°C, open the mold and take out the product to obtain the polymer composite material product used for pneumatic tires in this embodiment.

[0028] The polymer composite material prepared in this embodiment has a uniform internal structure, without obvious defects such as bubbles, cracks, filler agglomeration and delamination, and has good processing fluidity, demolding performance and dimensional stability.

[0029] Example 2 (The raw material composition and preparation method are basically the same as those in Example 1, except that the polycaprolactone diol ratio, pretreatment process and compression molding process parameters are adjusted.) Raw material composition The polymer composite material used in this embodiment is composed of the following parts by weight of raw materials: 55 parts polycaprolactone diol PCL1000, 45 parts polycaprolactone diol PCL2000, 49.0 parts MDI-100 isocyanate, 8.2 parts butanediol (BDO), 1.4 parts multi-walled carbon nanotubes, 4.4 parts silica, 1.7 parts polytetrafluoroethylene (PTFE) micro powder, 0.5 parts antioxidant, 0.4 parts UV absorber UV-531, 0.5 parts epoxy resin stabilizer, 1.6 parts dioctyl sebacate (DOS), 2.4 parts KH550 coupling agent, 0.4 parts defoamer, and 0.4 parts release agent.

[0030] (II) Preparation method S201: Weigh PCL1000 (55 parts) and PCL2000 (45 parts) according to the above ratio, add them to the reactor, and add 1% of the total mass of polycaprolactone as a dehydrating agent. Turn on the mechanical stirrer and control the stirring speed at 100 r / min. Raise the temperature to 120℃ and control the vacuum degree to ≤-0.095MPa. Under these conditions, dehydrate under constant temperature and vacuum for 1.5h. After dehydration, take 25% of the total mass of dehydrated polycaprolactone as the nanofiller dispersion carrier for later use.

[0031] S202: Add multi-walled carbon nanotubes, silica, PTFE powder and KH550 coupling agent to the 25% polycaprolactone carrier; A three-roll mill was used in conjunction with a high-speed shear mill for dispersion. The high-speed shear speed was controlled at 5000 r / min. The dispersion was continued until the fineness of the system was ≤20 μm, resulting in a uniformly dispersed filler mother liquor. The filler mother liquor was then thoroughly mixed with the remaining polycaprolactone for later use.

[0032] S203: Heat the above mixture to 60°C, and add MDI-100 after the polycaprolactone has completely melted. The system was then subjected to three cycles of vacuum nitrogen purging to fully isolate it from air and moisture. The temperature was then raised to 80°C, and the stirring speed was controlled at 320 r / min. The reaction was carried out at 80°C for 2 hours. After the prepolymerization reaction was completed, the resulting prepolymer was sealed and cooled to 45°C for later use.

[0033] S204: Add 0.1% of the total mass of the prepolymer to the obtained prepolymer to improve the crosslinking reaction rate, and add 0.5% of the non-silicone defoamer. Then add BDO chain extender and all the additives such as antioxidant, UV absorber UV-531, epoxy resin stabilizer, and DOS plasticizer. Start high-speed stirring at 2500 r / min and continue high-speed stirring for 60s to make the system uniformly mixed.

[0034] S205: Quickly transfer the mixed polyurethane system to a vacuum degassing device, control the vacuum degree to <-0.095MPa, degas for 3 minutes under constant temperature conditions, observe the liquid surface status in real time, and stop degassing immediately after the bubbles are basically eliminated to avoid premature gelation of the high viscosity system.

[0035] S206: Preheat the mold to 105℃ and spray the release agent evenly. Slowly pour the degassed polyurethane system into the mold. After pouring, close the mold. Control the molding temperature at 105℃, the molding pressure at 12MPa, and hold the pressure for 30 minutes to allow the polyurethane system to complete cross-linking and curing.

[0036] S207: Keep the mold closed and heat it in the mold for 3 hours to allow the polyurethane to crosslink more fully. Then, let it cool naturally at room temperature. When the mold temperature drops below 40°C, open the mold to obtain the polymer composite material product used for pneumatic tires in this embodiment.

[0037] The material prepared in this embodiment has a uniform internal structure and no obvious bubbles, cracks or filler agglomeration.

[0038] Example 3 (The preparation route is basically the same as that of Example 1, except for the polycaprolactone ratio, dehydration time, high-speed dispersion speed, catalyst addition amount, molding process and curing time) (I) Raw material composition The polymer composite material used in this embodiment is composed of the following parts by weight: 63 parts polycaprolactone diol PCL1000, 37 parts polycaprolactone diol PCL2000, 48 parts MDI-100 isocyanate, 7.6 parts butanediol (BDO), 1.1 parts multi-walled carbon nanotubes, 4.0 parts silica, 1.5 parts polytetrafluoroethylene (PTFE) micro powder, 0.4 parts antioxidant, 0.3 parts UV absorber (UV-531), 0.4 parts epoxy resin stabilizer, 2.0 parts dioctyl sebacate (DOS), 2.2 parts KH550 coupling agent, 0.3 parts defoamer, and 0.3 parts release agent.

[0039] (II) Preparation method S301: Weigh PCL1000 (63 parts) and PCL2000 (37 parts), add them to the reactor, and add 1% of the total mass of polycaprolactone as a dehydrating agent; Control the stirring speed to 100 r / min, raise the temperature to 115℃, maintain the vacuum degree ≤ -0.095MPa, and dehydrate at a constant temperature for 1.75h. After dehydration, take 25% of the total mass of dehydrated polycaprolactone as the nanofiller dispersion carrier for later use.

[0040] S302: Add multi-walled carbon nanotubes, fumed silica, PTFE powder and KH550 coupling agent to the above polycaprolactone carrier; disperse using a high-speed shearing machine at a shearing speed of 4000 r / min, and continue shearing until the fineness is ≤20 μm. The resulting filler mother liquor is thoroughly mixed with the remaining polycaprolactone for later use.

[0041] S303: Heat the mixture to 55℃, add MDI-100 after it is completely melted, and then perform vacuum nitrogen-purging cycle 3 times to form an anhydrous and oxygen-free reaction environment. Adjust the reaction temperature to 80℃, stir at 300r / min, and react at a constant temperature for 2 hours. After the reaction is completed, seal the prepolymer and cool it to 45℃ for later use.

[0042] S304: Add 0.08% of the total mass of the prepolymer, an organic bismuth catalyst, and 0.5% of the non-silicone defoamer to the prepolymer. Add BDO according to the chain extension coefficient f = 0.95, and add all the additives. Control the high-speed stirring speed at 2200 r / min and continue stirring for 75 s until the system forms a uniform and stable vortex and there is no BDO residue.

[0043] S305: Vacuum the mixed materials, control the vacuum degree to <-0.095MPa, and degas for 4 minutes under constant temperature conditions to fully remove residual bubbles in the system.

[0044] S306: Preheat the mold to 100℃, spray the release agent evenly, pour the polyurethane system smoothly, avoid air entrapment, close the mold after pouring, control the molding temperature to 100℃, the molding pressure to 10MPa, and hold the pressure for 35 minutes.

[0045] S307: After molding, continue to close the mold and keep it warm for 2.5 hours. Then slowly release the pressure and let it cool naturally. When the mold temperature drops below 35°C, open the mold to obtain the polymer composite material product used for pneumatic tires in this embodiment.

[0046] The polycaprolactone composite polyurethane material prepared in this embodiment also has good molding quality, with uniform internal structure and no obvious defects.

[0047] System performance tests were conducted on the samples prepared in Examples 1, 2 and 3. All samples were prepared according to the same process, and at least 5 samples were tested in each group. The final result was the arithmetic mean. All performance tests were conducted in a standard laboratory environment. After the samples were formed, they were left to stand at room temperature for 24 hours to release internal stress. The test environment temperature was 23±2℃ and the relative humidity was 50±5%.

[0048] I. General Testing Requirements (1) All tests were conducted at normal temperature and pressure (25℃, standard atmospheric pressure); (2) All samples were prepared according to the preparation process of the corresponding Examples 1, 2 and 3. After molding, they were left to stand at room temperature for more than 24 hours to fully release the internal stress before testing. (3) The appearance of the test samples should be flat, free from defects such as bubbles, cracks, filler agglomeration and delamination, and the dimensions should meet the requirements of the corresponding national standards. (4) Three parallel samples were prepared for each example, and the average value of each test result was taken to ensure the accuracy and repeatability of the test data.

[0049] II. Testing Implementation Standards Shore hardness: GB / T39693.4-2025 "Determination of hardness of vulcanized rubber or thermoplastic rubber", reading after 1 second of indentation dwell; Tensile properties: GB / T528-2009 "Determination of tensile stress-strain properties of vulcanized rubber or thermoplastic rubber" Type 1A dumbbell specimen, tensile speed 500mm / min; Compression set: GB / T7759.1-2015 "Determination of compression set of vulcanized rubber or thermoplastic rubber", compression ratio 25%, 70℃×24h; DIN abrasion resistance: GB / T9867-2008 "Determination of abrasion resistance of vulcanized rubber or thermoplastic rubber", standard grinding wheel, load 10N, test distance 40m; Taber abrasion test: GB / T39603-2021 "Determination of abrasion resistance of rubber - Taber abrasion method", 1000g load, CS-10 grinding wheel, test at 1000 revolutions, room temperature 23℃; Hot air aging: GB / T3512-2014 "Accelerated aging and heat resistance test of vulcanized rubber or thermoplastic rubber in hot air", aging conditions 100℃×72h; Rolling resistance coefficient: GB / T18861-2022 "Determination of rolling resistance of rubber tires by drum method", drum test speed 40km / h, room temperature 23℃; Glass transition temperature Tg: GB / T38082-2019 "Determination of dynamic mechanical properties of rubber and plastics - Forced non-resonance method"; Loss factor tanδ: GB / T38082-2019 "Determination of Dynamic Mechanical Properties of Rubber and Plastics - Forced Non-Resonance Method", scanning temperature -60℃~120℃, frequency 10Hz, strain 0.1%.

[0050] Depend on Figure 3 As can be seen, all three embodiments of the present invention exhibit good comprehensive mechanical properties. Embodiment 2 shows a tensile strength of 22.5 MPa, which is higher than that of Embodiments 1 and 3, while also exhibiting the lowest compression set at only 9.2%, indicating that Embodiment 2 has superior load-bearing capacity and elastic recovery performance. The various indicators of Embodiment 3 fall between those of Embodiments 1 and 2. Although the overall performance of Embodiment 1 is slightly lower, its elongation at break reaches 362%, demonstrating good flexibility. Comprehensive analysis shows that the present invention, through the synergistic effect of the polycaprolactone dual-soft-segment system and the nano-reinforcement system, can effectively improve the comprehensive mechanical properties of polyurethane elastomers.

[0051] Depend on Figure 4 It can be seen that all three embodiments of the present invention have excellent wear resistance. Among them, the DIN wear volume loss and TEB wear mass loss of embodiment 2 are the lowest, at 22.3 and 35.8 mg respectively, indicating that the synergistic friction reduction effect formed by PTFE micro powder and multi-walled carbon nanotubes is the most obvious. The wear resistance of embodiment 3 is slightly lower than that of embodiment 2, but significantly better than that of embodiment 1. No abnormal phenomena such as powder shedding or cracking were observed after wear in the three embodiments, proving that the material of the present invention has good wear resistance life and long-term use stability.

[0052] Depend on Figure 5It can be seen that the material of this invention maintains high mechanical properties after hot air aging. Example 2 exhibits the highest tensile strength retention rate, reaching 87.5%, with a hardness change of only +2 Shore A. No obvious yellowing or cracking was observed, demonstrating the best heat aging resistance. Example 3 is the second best. Although Example 1 has a slightly lower retention rate, it still reaches 81.2%, meeting the long-term service requirements of pneumatic tires. This indicates that the aging-resistant system composed of antioxidants, UV absorber UV-531, and epoxy resin stabilizers can effectively inhibit the degradation of polyurethane materials in a hot and oxygen-rich environment, improving the long-term reliability of the material.

[0053] comprehensive Figures 3-6 Test results show that the polymer composite material for pneumatic tires provided by this invention adopts a polycaprolactone diol dual soft segment system, a multi-walled carbon nanotube, a synergistic reinforcement system of fumed silica and PTFE micro powder, and an aging-resistant stabilizing system. By optimizing the prepolymerization, chain extension, degassing and molding curing processes, a polyurethane elastomer material with excellent comprehensive performance was obtained.

[0054] Example 1 showed relatively weak overall performance; Example 3 showed better overall performance than Example 1 but slightly lower than Example 2; Example 2 showed the best performance in terms of mechanical strength, wear resistance, and high-temperature aging stability. This indicates that the present invention, using a polycaprolactone dual soft segment system, multi-walled carbon nanotubes, silica, PTFE micropowder synergistic reinforcement system, and optimized polyurethane preparation process, can significantly improve the overall performance of polymer composite materials for pneumatic tires and has good prospects for industrial application.

[0055] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0056] Finally, it should be noted that the above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A polymeric composite material for pneumatic tires, characterized in that: It is prepared from the following raw materials in parts by weight: 55-65 parts polycaprolactone diol PCL1000, 35-45 parts polycaprolactone diol PCL2000, 45-50 parts isocyanate MDI-100, 5-10 parts butanediol BDO, 0.5-1.5 parts multi-walled carbon nanotubes, 3.5-4.5 parts silica, 1.2-1.8 parts polytetrafluoroethylene PTFE micro powder, 0.3-0.5 parts antioxidant, 0.2-0.4 parts ultraviolet absorber UV-531, 0.3-0.5 parts epoxy resin stabilizer, 1.5-2.5 parts plasticizer, 1.8-2.5 parts polyurethane coupling agent, 0.2-0.5 parts defoamer, and 0.2-0.4 parts release agent; The total mass fraction of polycaprolactone diol (PCL1000) and polycaprolactone diol (PCL2000) is 100 parts. The butanediol (BDO) is added according to a chain extension factor of 0.

95. The polyurethane coupling agent is aminopropyltriethoxysilane (KH550). The plasticizer is dioctyl sebacate (DOS). The defoamer is a non-silicone polyurethane defoamer. The remaining additives are based on the mass fraction of the 100 parts of polyol.

2. The polymer composite material for pneumatic tires according to claim 1, characterized in that: The polycaprolactone diol PCL1000 and polycaprolactone diol PCL2000 together constitute a polyurethane soft segment system, with polycaprolactone diols of different molecular weights forming a gradient of flexible segments. The isocyanate reacts with the polycaprolactone diol to form a polyurethane prepolymer, and the butanediol acts as a chain extender to construct a polyurethane crosslinking network.

3. The polymer composite material for pneumatic tires according to claim 1, characterized in that: The multi-walled carbon nanotubes, fumed silica, and polytetrafluoroethylene (PTFE) micropowder together form a ternary synergistic reinforcing network. The multi-walled carbon nanotubes are used to improve the tensile strength and fatigue resistance of the material, the fumed silica is used to improve the reinforcing performance and dimensional stability of the material, and the PTFE micropowder is dispersed in the polyurethane matrix to form a self-lubricating phase, and together with the multi-walled carbon nanotubes, it constructs a wear-resistant and friction-reducing network.

4. The polymer composite material for pneumatic tires according to claim 1, characterized in that: The plasticizer is selected as dioctyl sebacate (DOS), and the polyurethane coupling agent is selected as aminopropyltriethoxysilane (KH550). The polyurethane coupling agent forms an interfacial coupling layer with the hydroxyl groups on the surface of multi-walled carbon nanotubes, the silanol groups on the surface of silica, and the polyurethane matrix, so that the ternary synergistic reinforcing network is uniformly distributed in the continuous polyurethane phase. The antioxidant, ultraviolet absorber, and epoxy resin stabilizer together form an aging-resistant and stable system.

5. A method for preparing a polymer composite material for pneumatic tires, characterized in that, The specific operation steps of the polymer composite material for pneumatic tires as described in any one of claims 1-4 are as follows: Step 1: Weigh out polycaprolactone diol PCL1000 and polycaprolactone diol PCL2000 according to the formula ratio, add dehydrating agent and perform vacuum dehydration treatment to form a uniform dual soft segment polyurethane soft segment system. After dehydration, take 25% of the total mass of dehydrated polycaprolactone as the nanofiller dispersion carrier, and keep the remaining polycaprolactone warm for later use. Step 2: Add multi-walled carbon nanotubes, fumed silica, polytetrafluoroethylene powder and KH550 coupling agent to the polycaprolactone dispersion carrier, and disperse it using a high-speed shearing device or a three-roll mill to obtain a filler mother liquor. Then mix the filler mother liquor with the remaining polycaprolactone evenly. Step 3: Heat the mixed polycaprolactone system to 50-60°C until it is completely melted, then add... MDI-100 isocyanate was then subjected to 2-3 vacuum nitrogen-purging cycles to remove air and moisture from the system. The temperature was then raised to 80°C, and the stirring speed was controlled at 300-320 r / min. The reaction was kept at a constant temperature for 2 hours to form a polyurethane prepolymer. After the reaction was completed, the prepolymer was cooled to 45-50°C for later use. Step 4: Add catalyst, non-silicone defoamer, and butanediol chain extender calculated according to chain extension coefficient of 0.95 to polyurethane prepolymer. Then add antioxidant, UV absorber UV-531, epoxy resin stabilizer, dioctyl sebacate plasticizer, and release agent. Stir at high speed for 60-90 seconds to make the system uniformly mixed and complete the chain extension reaction. Step 5: Evacuate the mixed polyurethane system to a vacuum level less than -0.095 MPa, and maintain a constant temperature. Degas for 3-5 minutes under the specified conditions until the liquid surface is smooth and no continuous bubbles are produced. Step Six: Preheat the mold to 95-105℃, evenly spray the mold release agent into the mold, and then remove the foam. The polyurethane system is poured into the mold cavity, and the mold is closed after pouring is completed. Step 7: Control the molding temperature to 95–105℃, the molding pressure to 8–12 MPa, and hold the pressure for 30–30 minutes. The polyurethane system was allowed to cross-link and cure for 40 minutes. Step 8: Keep the mold closed and let it mature for 2-3 hours, then let it cool naturally until the mold temperature drops to 40℃. The following steps involve opening and demolding the mold to obtain a polymer composite material product for use in pneumatic tires.

6. The method for preparing a polymer composite material for pneumatic tires according to claim 5, characterized in that: In step one, the vacuum dehydration process involves heating the water to 110–120°C under mechanical stirring, controlling the stirring speed at 100 r / min, and maintaining the temperature for 1.5–2 hours under a vacuum level not exceeding -0.095 MPa.

7. The method for preparing a polymer composite material for pneumatic tires according to claim 5, characterized in that: The high-speed shearing rate in step two is 3500-5000 r / min, and the dispersion continues until the fineness of the system is no greater than 20 μm.

8. A method for preparing a polymer composite material for pneumatic tires according to claim 5, characterized in that: The catalyst in step four is an organobismuth catalyst or an organotin catalyst, and its addition amount is 0.05 to 0.10% of the total mass of the prepolymer. The stirring speed is controlled at 2000 to 2500 r / min.

Images