Low-energy-consumption high-adhesion electric vehicle tire puncture-resistant rubber and preparation method thereof, and puncture-resistant tire

Abstract

This invention discloses a low-energy-consumption, high-adhesion puncture-resistant rubber for electric vehicle tires, its preparation method, and the resulting puncture-resistant tire. Belonging to the field of rubber, the low-energy-consumption, high-adhesion puncture-resistant rubber for electric vehicle tires contains the following components: 80-90 PHR of grafted methyl methacrylate natural rubber, 10-20 PHR of high-styrene rubber, 30-40 PHR of nano-silicon-aluminum alloy material, 10-20 PHR of carbon black, 3-4 PHR of zinc oxide, 1.5-2.5 PHR of stearic acid, 3-5 PHR of antioxidant, 1.6-2.0 PHR of sulfur, and 0.8-1.2 PHR of sulfenamide accelerator. This invention combines the high hardness and high adhesive strength of grafted methyl methacrylate natural rubber with the superior high hardness of high-styrene rubber, and further utilizes 30-40 parts of nano-silicon-aluminum alloy material in the formulation to improve the tire's long-range performance, thus solving the problems of long-range performance, puncture resistance, and high adhesion performance. This puncture-resistant rubber is a layer bonded between the tread rubber and the ply layer. Its Shore hardness reaches 72, which not only gives the tire the advantage of puncture resistance, but also does not affect the tire's comfort and anti-slip performance because it is located inside the tread rubber.

Description

Technical Field

[0001] This invention aims to emphasize the use of grafted methyl methacrylate natural rubber, high-styrene rubber and nano-silicon aluminum alloy materials to obtain a mixed polymer. The puncture-resistant rubber prepared using this polymer can not only meet the puncture resistance function of tires, but also meet the low rolling resistance (long range) performance of tires. Background Technology

[0002] The tread compound is the outermost rubber layer of the tire that directly contacts the road surface. Its patterned surface primarily transmits traction and braking force, cushions driving impacts, and protects the tire's internal structure. The Shore hardness of the tread compound is typically between 58 and 65. Excessive hardness significantly reduces tire grip and comfort, and increases driving risks; insufficient hardness leads to poor tire wear resistance, easy damage, and a short lifespan. The crown compound is the core part of the tread compound located at the front of the tire, bearing the main load and friction. The ply layer is the core skeleton structure of the pneumatic tire, composed of multiple layers of rubber-coated cords. Its main functions are to bear loads, maintain tire shape, transmit traction and braking force, and ensure strength and stability during driving. A buffer layer (or belt layer) is usually placed between the tread compound and the ply layer. Its main functions are to mitigate road impacts, enhance the adhesion between the tread and the ply layer, and reduce damage to the internal structure caused by shear stress during driving.

[0003] Currently, most two-wheeled electric vehicle tires on the market require long-range performance. To meet this requirement, the hardness of the tire tread rubber is relatively low, resulting in poor puncture resistance. Consequently, to meet puncture resistance requirements, a layer of steel cord (i.e., belt layer) is often added to the tire carcass ply. However, adding steel cord reduces tire comfort and weakens the adhesion between the steel cord and the rubber, making the tire more prone to premature damage.

[0004] The market demands increasingly higher performance from tires for two-wheeled electric vehicles, requiring not only safety (puncture resistance and durability) but also economic efficiency (long range) and minimizing the negative impacts of steel cord tires. This has prompted researchers to seek alternative solutions to this problem.

[0005] Tianjia rubber, an industrial product of methyl methacrylate grafted natural rubber, is mainly classified as MG-30 (grafting rate 30%) and MG-49 (grafting rate 49%). Higher grafting rates result in higher hardness. Currently, its application in adhesives and non-tire rubber products is widely reported (e.g., CN105348581B, CN109401676A), but its application in tire formulations is less frequently reported. Compared to ordinary natural rubber, grafted methyl methacrylate natural rubber has higher hardness and improved strength and adhesion. Therefore, some technologies use it as a modifier for the base rubber material in tire tread compounds, at a dosage of approximately 10%, to improve the wear resistance of the tire tread compound. Furthermore, CN105131777B reports the preparation of a coating liquid by dissolving Tianjia rubber and materials such as coumarone resin in a solvent, which is then applied to the bead wires. The resulting coating effectively improves the adhesion between the bead wires and the bead rubber, but it is not used in tire tread compound formulations to replace raw rubber such as natural rubber. These applications demonstrate that methyl methacrylate-grafted natural rubber is difficult to directly replace natural rubber as the base rubber for tires. Summary of the Invention

[0006] By implementing the low-energy-consumption, high-adhesion puncture-resistant rubber for electric vehicle tires of the present invention, the problems of current two-wheeled electric vehicle tires being not puncture-resistant and prone to bulging and delamination can be solved.

[0007] The low-energy, high-adhesion, puncture-resistant rubber for electric vehicle tires contains the following components in its formulation:

[0008] Grafted methyl methacrylate natural rubber 80-90 PHR, high styrene rubber 10-20 PHR, nano-silicon aluminum alloy material 30-40 PHR, carbon black 2-5 PHR, zinc oxide 3-4 PHR, stearic acid 1.5-2.5 PHR, antioxidant 3-5 PHR, sulfur 1.6-2.0 PHR, sulfenamide accelerator 0.8-1.2 PHR.

[0009] Grafted methyl methacrylate natural rubber, preferably MGA-30 from Qixiang New Materials, has a Tg of -65℃, a raw rubber hardness of Shore 80, and a methyl methacrylate content of 30%. Compared with ordinary natural rubber, its hardness, strength, and adhesive properties are all improved. This invention uses grafted methyl methacrylate natural rubber as the main rubber material for the puncture-resistant rubber of electric vehicle tires. MGA-49 grafted methyl methacrylate natural rubber with a grafting rate of 49% has excessively high hardness, which would lead to increased rolling resistance and is not conducive to making low-energy tires. Therefore, this invention prefers MGA-30.

[0010] High-styrene rubber, preferably HS860, is a type of styrene-butadiene rubber with a styrene content between 55% and 65%. This material can further improve the hardness of grafted methyl methacrylate rubber.

[0011] The nano-silicon-aluminum alloy uses Shanzhen's NSA04, a functional material specifically designed to improve tire wet grip, wear resistance, and rolling resistance (nano-silicon-aluminum (Al2SiO5.nH2O) with an average particle size of approximately 500nm). The mechanism of action of the nano-silicon-aluminum alloy mainly lies in its unique physicochemical properties and the formation of hard Al-O-Si bonded compounds during the vulcanization process, which punctures the water film between the tire and the road surface. This improves tire grip on wet roads, allowing it to form a good interfacial bond with the rubber matrix, and also enhances the rubber's wear resistance, reduces heat generation, and improves fatigue resistance. Using nano-silicon-aluminum alloy materials to reinforce grafted methyl methacrylate natural rubber and high-styrene rubber reduces rolling resistance and ensures the compound's hardness reaches Shore A hardness of 72. A Shore A hardness of around 72 improves the puncture resistance of electric vehicle tires; a Shore A hardness below 70 significantly affects puncture resistance. Because the rubber compound has a high hardness, significantly higher than the tread compound, the puncture-resistant rubber is bonded between the tread compound and the ply layer, improving puncture resistance without affecting tread performance.

[0012] Other materials can be added to the low-energy, high-adhesion puncture-resistant rubber formula for electric vehicle tires for color mixing.

[0013] Preferably, the low-energy-consumption, high-adhesion puncture-resistant rubber for electric vehicle tires contains the following components in its formulation:

[0014] Grafted methyl methacrylate natural rubber 88-90 PHR, high styrene rubber 10-12 PHR, nano-silicon aluminum alloy material 30-35 PHR, carbon black 2-5 PHR, zinc oxide 3-4 PHR, stearic acid 1.5-2.5 PHR, antioxidant 3-5 PHR, sulfur 1.6-2.0 PHR, sulfenamide accelerator 0.8-1.2 PHR.

[0015] Antioxidants can be p-phenylenediamine-based antioxidants (such as 6PPD, IPPD, 4020), with 4020 being the preferred antioxidant. For sulfenamide accelerators, N-cyclohexyl-2-benzothiazole sulfenamide, also known as CZ, is preferred.

[0016] When specific raw materials are not explicitly specified in the embodiments of this invention, the preferred materials and proportions in the scheme of this invention shall be used.

[0017] This invention also provides a method for preparing the low-energy-consumption, high-adhesion puncture-resistant rubber for electric vehicle tires, which is prepared using a three-stage internal mixer F370, and includes the following steps:

[0018] The process of making masterbatch involves using an internal mixer to plasticize grafted methyl methacrylate natural rubber and high-styrene rubber, then adding nano-silicon-aluminum alloy and continuing to mix. The mixture is then discharged after the temperature reaches 155°C to obtain the masterbatch.

[0019] Two-stage mixing: Using a constant-speed internal mixing process, the masterbatch and other raw materials except for sulfur and sulfenamide accelerators are mixed. After the temperature reaches 155℃, the material is discharged to obtain the two-stage compound.

[0020] Three-stage final mixing: Using a self-mixing machine at a constant speed, the two-stage compound rubber is mixed and vulcanized with sulfur and sulfenamide accelerators. After the temperature reaches 95°C, the material is discharged to obtain a low-energy-consumption, high-adhesion, puncture-resistant electric vehicle tire rubber.

[0021] A further technical solution involves the following steps in the preparation method:

[0022] The first stage of masterbatch production: An F370 internal mixer is used. The internal mixer speed is 50 rpm to plasticize the grafted methyl methacrylate natural rubber and high-styrene rubber for 30 seconds, then nano-silicon-aluminum alloy is added and processed for another 30 seconds. The speed is then reduced to 25 rpm. Finally, the material is discharged after the temperature inside the internal mixer reaches 155℃, producing the masterbatch. In this stage of rubber mixing, the internal mixer speed is changed from 50 rpm to 25 rpm. The higher speed is used in the early stage to quickly disperse the various components, and the lower speed is used in the later stage to facilitate control of the temperature rise rate inside the internal mixer, so that the masterbatch can be switched to the second stage of mixing in time when it reaches 155℃.

[0023] Two-stage mixing: The internal mixer F370 is used for operation. The internal mixer speed is kept constant (40 rpm). When the internal mixer speed display shows 40 rpm, the masterbatch and other raw materials (carbon black, zinc oxide, stearic acid, antioxidant) except sulfur and sulfenamide accelerators are added. After 50 seconds of operation, the mixture is cleaned. After the temperature of the mixing chamber reaches 155℃, the material is discharged to obtain the two-stage compound.

[0024] Three-stage final mixing: The final mixing is carried out using an F370 internal mixer at a speed of 25 rpm. After adding the second-stage compound rubber, sulfur, and sulfenamide accelerators, the rubber is mixed for 50 minutes and then cleaned. After unloading at 95°C, low-energy, high-adhesion, puncture-resistant rubber for electric vehicle tires is obtained.

[0025] The first stage primarily involves plasticizing the raw rubber and mixing it with some compounding agents; the second stage further disperses the fillers and cools the mixture; the third stage adds crosslinking agents such as sulfur to ensure a uniform distribution of the vulcanization system. This staged approach improves the stability of the rubber compound's quality. Mechanical shearing during mixing generates a significant amount of heat. If all mixing is completed at once, excessively high temperatures can easily lead to premature vulcanization (i.e., "scorching"). In the three-stage process, each stage of mixing is followed by cooling and resting, effectively controlling the temperature and ensuring safety when finally adding sulfur.

[0026] A puncture-resistant tire includes a tread compound and a ply layer, wherein the aforementioned low-energy, high-adhesion puncture-resistant rubber layer for electric vehicles is disposed between the tread compound and the ply layer. The preferred thickness of the low-energy, high-adhesion puncture-resistant rubber layer for electric vehicles is 2-3 mm.

[0027] Compared with the prior art, the present invention has achieved at least the following beneficial effects:

[0028] This invention combines the high hardness and high adhesive strength of grafted methyl methacrylate natural rubber with the superior high hardness of high-styrene rubber. The formulation further incorporates 30-40 parts of nano-silicon-aluminum alloy material to enhance tire range, thus solving the problems of long range, puncture resistance, and high adhesion performance. The puncture-resistant adhesive of this invention is a layer bonded between the tread rubber and the ply layer, achieving a Shore hardness of 72. This puncture-resistant adhesive not only gives the tire puncture resistance but also, because it is located inside the tread rubber, does not affect the tire's comfort or wet grip performance. Detailed Implementation

[0029] Preparation method of electric vehicle puncture-resistant adhesive in examples and comparative examples:

[0030] The process uses a three-stage internal mixer (F370). Stage 1: Masterbatch mixing: The F370 internal mixer is used with variable speed operation (50 rpm to 25 rpm). At 50 rpm, grafted methyl methacrylate natural rubber and high-styrene rubber are mixed for 30 seconds. Then, nano-silicon-aluminum alloy is added and mixed for another 30 seconds before the speed is reduced to 25 rpm. Finally, the mixture is discharged after the temperature reaches 155°C, producing the masterbatch. Stage 2: Mixing: The F370 internal mixer is used with a constant speed (40 rpm). When the speed reaches 40 rpm, the masterbatch and other raw materials (excluding sulfur and sulfenamide accelerators) are added. After 50 seconds of mixing, the mixture is cleaned. The mixture is discharged after the temperature in the mixing chamber reaches 155°C. Three-stage final mixing: The final mixing is carried out using an F370 internal mixer at a speed of 25 rpm. After adding the second-stage compound rubber, sulfur, and sulfenamide accelerators, the rubber is mixed for 50 minutes and then cleaned. After unloading at 95°C, low-energy, high-adhesion, puncture-resistant rubber for electric vehicle tires is obtained.

[0031] Table 1. Raw material ratios for the examples and comparative examples

[0032] Material Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 Comparative Example 3 Grafted Methyl Methacrylate Natural Gum 80 85 90 0 100 90 Common natural rubber 0 0 0 90 0 0 High styrene rubber 20 15 10 10 0 10 Nano-silicon aluminum alloy 40 35 30 30 30 0 carbon black 3 3 3 3 0 30 Zinc oxide 3.5 3.5 3.5 3.5 3.5 3.5 stearic acid 2.0 2.0 2.0 2.0 2.0 2.0 Anti-aging agents 3 3 3 3 3 3 sulfur 1.8 1.9 2 2 2 2 Sulfoamide accelerators 1.0 1.0 1.0 1.0 1.0 1.0

[0033] The standards for testing the Shore hardness, tensile strength, elongation at a given point, elongation, finished product compressive strength, rolling resistance, and peel strength of the rubber compound are as follows:

[0034] Shore hardness test standard: GB / T 39693.4-2025 Determination of hardness of vulcanized or thermoplastic rubber - Part 4: Determination of indentation hardness by Shore hardness tester method (Shore A);

[0035] Standard for determination of tensile strength and elongation at break: HG / T 2580-2022;

[0036] Standard for cylindrical compressive strength testing: GB / T 13203-2021 Test methods for motorcycle tire performance;

[0037] Rolling resistance test standard: GB / T 18861-2012 Test method for rolling resistance of automobile tires and motorcycle tires

[0038] Tire peel strength test standard: GB / T 532-2008 Test for adhesive strength of vulcanized rubber or fabric;

[0039] Sampling: Take a sample (width * length) of 25mm * 200mm along the tire travel direction and measure the adhesion between the rubber compound and the ply layer at the tread area on a tensile testing machine.

[0040] Durability and running performance testing standard: The laboratory durability and running performance of tires shall be determined in accordance with GB / T 4570-2022;

[0041] Mileage test: Tire actual vehicle mileage test 20,000 kilometers.

[0042] The hardness and other properties of the puncture-resistant rubber for low-energy-consumption, high-adhesion electric vehicle tires were tested. Then, the puncture-resistant rubber for low-energy-consumption, high-adhesion electric vehicle tires was placed between the tire tread rubber and the cord layer with a thickness of 2.5 mm. Then, the peel strength and other properties were tested. The test results of the rubber properties of the examples and comparative examples are shown in Table 2.

[0043] Table 2. Properties of the rubber compounds in the examples and comparative examples.

[0044] project Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 Comparative Example 3 Shore hardness (rubber compound) 72 72 72 68 67 68 Tensile strength (MPa) (rubber compound) 20.5 21.5 22.0 18.6 20.6 20.5 Fixed elongation (M100) (MPa) (rubber compound) 10.5 10.6 10.8 8.6 8.6 8.5 Elongation (%) (rubber compound) 425 411 415 510 511 515 Column compressive strength J (finished product) 64 65 66 58 57 62 Rolling resistance test N (the smaller the value, the better) (finished product) 16 16.5 16.3 16.5 16.6 20 Peel strength (KN / m, finished product) 16 15.6 16.3 13.5 16.3 16.3 Durable running (finished product) No abnormalities were found at the end of the walk. No abnormalities were found at the end of the walk. No abnormalities were found at the end of the walk. No abnormalities were found at the end of the walk. No abnormalities were found at the end of the walk. No abnormalities were found at the end of the walk. Mileage test (finished product) No abnormalities found in the inner tube after 20,000 kilometers No abnormalities found in the inner tube after 20,000 kilometers No abnormalities found in the inner tube after 20,000 kilometers No abnormalities found in the inner tube after 20,000 kilometers No abnormalities found in the inner tube after 20,000 kilometers No abnormalities found in the inner tube after 20,000 kilometers

[0045] Comparative Example 1 uses ordinary natural rubber as the main base rubber instead of the grafted methyl methacrylate natural rubber in Example 3. Other raw materials are the same as in Example 3. In addition to low Shore hardness and low column compression strength, the rubber compound of Comparative Example 1 also has low peel strength. When the peel strength is insufficient, the adhesion between the various layers of tire materials (such as tread rubber and puncture-resistant rubber) is not strong, and they are prone to separation under long-term stress, high temperature or impact.

[0046] Comparative Example 2 used 100 parts of grafted methyl methacrylate natural rubber as the base rubber, without using high-styrene rubber for compounding. Other raw materials were the same as in Example 3. Compared with Example 3, Comparative Example 2 had lower Shore hardness and lower column compressive strength. Compared with Comparative Example 1, due to the use of more grafted methyl methacrylate natural rubber, the peel strength of Comparative Example 2 was improved, but both Shore hardness and column compressive strength were reduced.

[0047] The long-range performance of a tire is related to its rolling resistance performance; lower rolling resistance results in better long-range performance. Examples 1-3 and Comparative Examples 1-2 all used nano-silicon-aluminum alloy materials, and the rolling resistance of these examples was comparable to that of the comparative examples. Comparative Example 3 did not use nano-silicon-aluminum alloy materials, but it used more carbon black than the examples and other comparative examples to replace the nano-silicon-aluminum alloy materials for reinforcement. As can be seen from Table 2, the rolling resistance of Comparative Example 3 was significantly improved.

[0048] Tire puncture resistance is mainly related to the tire's compressive strength and the hardness of the rubber compound. As shown in Table 2, the hardness and compressive strength of the tires in the examples are better than those in the three comparative examples, indicating that the tires in the examples have better puncture resistance than the comparative examples. All examples have low rolling resistance, thus the tires have good long-range performance.

[0049] The mixture using nano-silicon-aluminum alloy materials, grafted methacrylate natural rubber, and high-styrene rubber ensures both rolling resistance (long range) and compressive strength and compound hardness (puncture resistance). The puncture-resistant rubber is bonded between the tread compound and the ply layer, improving the tire's puncture resistance without affecting tread performance.

Claims

1. A low energy, high adhesion electric vehicle tire puncture resistant rubber, characterized in that, It contains the following components: Grafted methyl methacrylate natural rubber 80-90 PHR, high styrene rubber 10-20 PHR, nano-silicon aluminum alloy material 30-40 PHR, carbon black 2-5 PHR, zinc oxide 3-4 PHR, stearic acid 1.5-2.5 PHR, antioxidant 3-5 PHR, sulfur 1.6-2.0 PHR, sulfenamide accelerator 0.8-1.2 PHR.

2. The low-energy-consumption, high-adhesion puncture-resistant rubber for electric vehicle tires according to claim 1, characterized in that, The grafted methyl methacrylate natural rubber used is MGA-30 from Qixiang New Materials.

3. The low-energy-consumption, high-adhesion, puncture-resistant rubber for electric vehicle tires according to claim 2, characterized in that, The styrene content of the high-styrene rubber is between 55% and 65%.

4. The low-energy-consumption, high-adhesion, puncture-resistant rubber for electric vehicle tires according to claim 3, characterized in that, The nano-silicon-aluminum alloy uses NSA04 from Shanzhen.

5. The low-energy-consumption, high-adhesion, puncture-resistant rubber for electric vehicle tires according to any one of claims 1-4, characterized in that, It contains the following components: Grafted methyl methacrylate natural rubber 88-90 PHR, high styrene rubber 10-12 PHR, nano-silicon aluminum alloy material 30-35 PHR, carbon black 2-5 PHR, zinc oxide 3-4 PHR, stearic acid 1.5-2.5 PHR, antioxidant 3-5 PHR, sulfur 1.6-2.0 PHR, sulfenamide accelerator 0.8-1.2 PHR.

6. The low-energy-consumption, high-adhesion puncture-resistant rubber for electric vehicle tires according to claim 5, characterized in that, The antioxidant is a p-phenylenediamine-based antioxidant.

7. The low-energy-consumption, high-adhesion puncture-resistant rubber for electric vehicle tires according to claim 6, characterized in that, The sulfonamide accelerator is N-cyclohexyl-2-benzothiazole sulfonamide.

8. The method for preparing the low-energy-consumption, high-adhesion puncture-resistant rubber for electric vehicle tires according to any one of claims 1-7, characterized in that, The preparation is carried out using a three-stage internal mixer, which includes the following steps: The process of making masterbatch involves using an internal mixer to plasticize grafted methyl methacrylate natural rubber and high-styrene rubber, then adding nano-silicon-aluminum alloy and continuing to mix. The mixture is then discharged after the temperature reaches 155°C to obtain the masterbatch. Two-stage mixing: Using a constant-speed internal mixing process, the masterbatch and other raw materials except for sulfur and sulfenamide accelerators are mixed. After the temperature reaches 155℃, the material is discharged to obtain the two-stage compound. Three-stage final mixing: Using a self-mixing machine at a constant speed, the two-stage compound rubber is mixed and vulcanized with sulfur and sulfenamide accelerators. After the temperature reaches 95°C, the material is discharged to obtain a low-energy-consumption, high-adhesion, puncture-resistant electric vehicle tire rubber.

9. The method for preparing the low-energy-consumption, high-adhesion puncture-resistant adhesive for electric vehicle tires according to claim 8, characterized in that, The process of making the masterbatch involves mixing grafted methyl methacrylate natural rubber and high-styrene rubber in a mixer at 50 rpm for 30 seconds, then adding nano-silicon-aluminum alloy and mixing for another 30 seconds. After that, the speed is reduced to 25 rpm until the temperature reaches 155°C, at which point the mixture is unloaded. Two-stage mixing: When the speed of the internal mixer is 40 rpm, add the masterbatch and other raw materials except sulfur and sulfenamide accelerators. Clean up after 50 seconds of operation, and unload the material when the temperature of the internal mixer reaches 155℃. Three-stage final mixing: The speed is 25 rpm. After adding the second-stage compound rubber, sulfur, and sulfenamide accelerator, the rubber is mixed for 50 minutes and then cleaned. The material is discharged when the temperature of the mixing chamber reaches 95°C.

10. A puncture-resistant tire, comprising a tread compound and a ply, characterized in that, The tread rubber and the ply layer are provided with a low-energy-consumption, high-adhesion, puncture-resistant rubber layer for electric vehicle tires as described in any one of claims 1-7.