High-torque high-flexibility transmission belt and preparation method thereof

Abstract

The invention discloses a high-torque high-flexibility transmission belt which is composed of an outer rubber layer, a middle reinforcing layer and an inner rubber layer, the outer rubber layer comprises, by weight, 60-80 parts of nitrile rubber, 20-40 parts of polyurethane, 1-2 parts of an antioxidant and 5-15 parts of a reinforcing agent, and the reinforcing agent comprises sulfonated cellulose nanowhiskers, lignosulfonate and graphene oxide; the middle reinforcing layer comprises 50-80 parts of carbon fibers and 20-40 parts of aramid fibers; the inner rubber layer comprises 70-90 parts of natural rubber and 30-50 parts of butadiene rubber; the preparation method comprises the following steps: mixing components of the outer rubber layer to obtain outer rubber; mixing the components of the inner rubber layer to obtain inner rubber; the components of the middle reinforcing layer are woven into plain weave fabric; the plain weave fabric is pressed on the inner-layer rubber, the outer-layer rubber covers the plain weave fabric, a belt blank is obtained through hot pressing, the belt blank is cooled and shaped, and the transmission belt prepared from the components through the method has high torque and high flexibility.

Description

Technical Field

[0001] This application relates to the field of transmission belt technology, and in particular to a high-torque, high-flexibility transmission belt and its preparation method. Background Technology

[0002] Drive belts, especially those used in continuously variable transmissions (CVT) systems for motorcycles, are the core components for transmitting power and achieving gear changes. Their performance directly affects transmission efficiency, smoothness, and service life. Currently, these drive belts are typically made of rubber composite materials and reinforced with built-in high-strength fiber cords or fabrics as a reinforcing skeleton to withstand tensile stress during operation. Common reinforcing fibers include polyester, glass fiber, or aramid.

[0003] However, when applied to motorcycle drivetrain systems, traditional drive belts have shortcomings in terms of torque capacity and flexible transmission. Motorcycle drive belts need to frequently and rapidly wrap around pulleys of different diameters during operation, requiring excellent bending flexibility. Traditional drive belts struggle to meet these multi-directional bending and torsional flexibility requirements while maintaining high torque capacity, which can easily lead to unstable transmission, vibration, and noise. Summary of the Invention

[0004] To address the shortcomings of traditional transmission belts in torque bearing and flexible transmission when applied to motorcycle transmission systems, a high-torque, high-flexibility transmission belt and its preparation method are provided.

[0005] The above-mentioned objective of this invention is achieved through the following technical solutions: A high-torque, high-flexibility transmission belt consists of an outer rubber layer, a middle reinforcing layer, and an inner rubber layer. The outer rubber layer comprises the following components in parts by weight: 60-80 parts of nitrile rubber, 20-40 parts of polyurethane, 1-2 parts of antioxidant, and 5-15 parts of reinforcing agent, including sulfonated cellulose nanofibers, lignin sulfonate, and graphene oxide. The intermediate reinforcing layer comprises the following components in parts by weight: 50-80 parts carbon fiber and 20-40 parts aramid fiber; The inner rubber layer comprises the following components by weight: 70-90 parts natural rubber and 30-50 parts butadiene rubber. By employing the above technical solution, in the outer rubber layer, nitrile rubber provides oil resistance and abrasion resistance, while polyurethane contributes high elasticity and toughness. The two are blended to form a flexible matrix. The reinforcing agents include sulfonated cellulose nanofibers and graphene oxide. The sulfonated cellulose nanofibers possess a nanoscale rigid rod-like structure and a high specific surface area, enabling them to form a dense hydrogen bond network with the polar groups (such as cyano and ester groups) of nitrile rubber and polyurethane through a large number of hydroxyl groups on their surface. This anchors the rubber molecular chains to the surface of the whiskers, forming physical cross-linking points. When the material is subjected to stress, the stress can be efficiently transferred from the flexible rubber molecular chains to the rigid whiskers through hydrogen bonds and van der Waals forces. Lignosulfonates inhibit the relative slippage of molecular chains, thereby improving the torque and flexibility of the material. They possess an amphiphilic molecular structure; their hydrophobic aromatic ring skeleton has good compatibility with rubber molecular chains, allowing them to intertwine through van der Waals forces. The hydrophilic sulfonic acid groups can form ionic or hydrogen bonds with the polar regions in the rubber, thus improving the interfacial compatibility between the filler and the matrix and reducing phase separation. Lignosulfonates themselves have long, flexible molecular chains; when subjected to external forces, their chains can absorb and dissipate energy through conformational changes and the movement of molecular chain segments, thereby preventing the initiation and propagation of microcracks and playing a role in toughening and inhibiting crack development. Lignosulfonates can adsorb onto the surface of sulfonated cellulose nanocrystals, utilizing their steric hindrance effect. To prevent the agglomeration of nanocrystals due to their high surface energy, it is crucial to promote their uniform dispersion within the rubber matrix, thereby enhancing the nano-reinforcing network. Simultaneously, the flexible long chains of lignin sulfonate act as a "flexible bridge" between the rigid nanocrystals and the rubber matrix, optimizing interfacial stress transfer and enabling the material to maintain good toughness and fracture resistance while achieving high modulus. Graphene oxide possesses extremely high specific surface area and mechanical strength, enabling it to form a three-dimensional network structure within the rubber matrix. Through stress transfer and crack deflection mechanisms, it effectively bears and disperses loads. When microcracks appear within the material, the crack tip encounters the hard graphene oxide sheets during propagation, forcing its propagation path to change, detour, or branch, thus consuming more energy and hindering the propagation. The rapid propagation of cracks increases the material's torque, and its reversible deformation and recovery under stress provide reinforcement without causing embrittlement like traditional rigid fillers. The intermediate reinforcement layer uses carbon fiber and aramid fiber; carbon fiber provides high modulus and tensile strength, while aramid fiber contributes high toughness and impact resistance. The two are woven into a plain weave fabric to form a rigid skeleton that bears the main torque load and distributes stress evenly through the interlacing points between the fibers. In the inner rubber layer, natural rubber provides high elasticity and flexibility, while butadiene rubber contributes low-temperature flexibility and dynamic fatigue resistance. Together, they ensure the drive belt has excellent deformation capacity when bent. In summary, the drive belt achieves a balance between high torque and high flexibility, extending its service life.

[0006] Optionally, the mass ratio of sulfonated cellulose nanocrystals to lignin sulfonate is (5–8):1.

[0007] By adopting the above technical solution, sulfonated cellulose nanofibers have high rigidity but are prone to agglomeration. Lignosulfonate, as a bio-based surfactant, can encapsulate sulfonated cellulose nanofibers through its sulfonic acid groups and hydroxyl groups, reducing agglomeration and promoting uniform dispersion in rubber. At the same time, the flexible segments of lignin sulfonate and the rigid structure of sulfonated cellulose nanofibers form a complementary rigid-flexible structure, enhancing the toughness and strength of the rubber matrix. This ratio allows the reinforcing agent to be dispersed more uniformly in the rubber and achieve better interfacial bonding, thereby more effectively improving the torque transmission efficiency of the conveyor belt. Meanwhile, by improving stress distribution, local stress concentration is avoided, and flexibility is maintained.

[0008] Optionally, the lignin sulfonate is calcium lignin sulfonate.

[0009] By adopting the above technical solution, calcium ions can form ionic bonds with polar groups in rubber molecules (such as the cyano group in nitrile rubber). These weak ionic bonds can be reversibly broken and reformed under dynamic load, thereby dissipating energy and improving the toughness and fatigue resistance of rubber. At the same time, the calcium sulfonate group has good thermal stability and can maintain dispersion during processing to prevent degradation. Compared with other salts, calcium ions have a moderate radius and can more effectively form uniform crosslinks with the rubber network without affecting flowability, making the transmission belt more stable under high pressure. The energy dissipation mechanism enhances flexibility, making the transmission belt less prone to cracking during repeated bending.

[0010] Optionally, the graphene oxide is treated with an aminosilane coupling agent.

[0011] By adopting the above technical solution, the amino group (-NH2) in the aminosilane coupling agent covalently bonds with the oxygen-containing functional groups (such as carboxyl groups) on the surface of graphene oxide, while the silane group reacts with the rubber molecular chain to form chemical bridges, making the graphene oxide more uniformly dispersed in the rubber matrix, preventing agglomeration, and improving the interfacial stress transfer efficiency. The amino group can also form hydrogen bonds with the polar part in the rubber (such as the cyano group in nitrile rubber), further enhancing interfacial adhesion, improving the modulus and tensile strength of the outer rubber layer, thereby improving the torque capacity and flexibility of the transmission belt.

[0012] Optionally, the antioxidant may be a phenolic antioxidant.

[0013] By adopting the above technical solution, when the transmission belt heats up during high torque operation, the antioxidant provides hydrogen atoms through its phenolic hydroxyl groups to capture the free radicals generated by the rubber during thermo-oxidative aging, interrupting the oxidation chain reaction, thereby slowing down the breakage of the rubber molecular chain and the change in crosslinking density, and avoiding the reaction of other components during the preparation process that would cause a decline in performance.

[0014] Optionally, the carbon fiber is subjected to oxidative modification.

[0015] By employing the above technical solution, oxidation treatment introduces oxygen-containing functional groups such as carboxyl and hydroxyl groups onto the surface of carbon fibers, increasing surface energy and polarity, thereby improving wettability and chemical affinity with the rubber matrix. This enhances the interfacial adhesion between carbon fibers and rubber, allowing stress to be transferred more efficiently from rubber to fibers through chemical bonds and mechanical interlocking, reducing interfacial slippage, improving the stiffness and strength of the intermediate reinforcing layer, enabling the transmission belt to withstand higher torques, and improving flexibility.

[0016] Optionally, the aramid fibers are treated with low-temperature plasma.

[0017] By adopting the above technical solution, low-temperature plasma treatment introduces polar functional groups (such as hydroxyl or carboxyl groups) by bombarding the surface of aramid fibers with high-energy particles, increases surface roughness, and removes contaminants, thereby improving the wettability and chemical affinity between the fiber and the rubber matrix, enhancing the interfacial bonding strength, and enabling stress to be transferred more effectively from the rubber to the fiber. This improves the flexibility of the transmission belt and reduces the risk of breakage under high torque.

[0018] The second objective of this invention is achieved through the following technical solution: The preparation method of any of the above-mentioned high-torque, high-flexibility transmission belts includes the following steps: S1: Nitrile rubber, polyurethane, graphene oxide, reinforcing agent and antioxidant are mixed to obtain the outer layer rubber; S2: The inner layer rubber is obtained by mixing natural rubber and butadiene rubber; S3: Weave carbon fiber and aramid fiber into a plain weave fabric; S4: Press the plain weave fabric onto the inner adhesive layer, cover the plain weave fabric with the outer adhesive layer, and hot press to obtain a strip blank. The strip blank is then cooled and shaped.

[0019] By adopting the above technical solution, the mixing in step S1 ensures that nitrile rubber, polyurethane, graphene oxide, lignin sulfonate, and sulfonated cellulose nanofibers are uniformly dispersed to form a reinforcing network for the outer layer rubber; the mixing in step S2 fully mixes natural rubber and cis-butadiene rubber to provide an elastic matrix for the inner layer rubber; the weaving in step S3 forms a plain weave fabric with carbon fiber and aramid fiber to achieve uniform stress distribution; the pressing and hot pressing in step S4 promote the interfacial bonding between layers, form a strong structure through thermal activation crosslinking reaction, and stabilize the dimensions by cooling and shaping; the transmission belt prepared in this way has high structural integrity and interlayer bonding strength, as well as high torque transmission efficiency and flexibility.

[0020] In summary, this application has at least the following beneficial effects: (1) Sulfonated cellulose nanocrystals have a nanoscale rigid rod-like structure and a high specific surface area. Their surface hydroxyl groups can form a dense hydrogen bond network with rubber polar groups, anchoring the molecular chain. When subjected to force, stress is efficiently transferred, slippage is suppressed, and the torque and flexibility of the material are improved. (2) Lignosulfonates have an amphiphilic structure. The hydrophobic skeleton is compatible with rubber and entangles with it. The hydrophilic groups form ionic bonds or hydrogen bonds, which improves the interfacial compatibility. Its flexible chain can absorb and dissipate energy, prevent crack initiation and propagation, and play a toughening role. (3) Lignosulfonates are adsorbed on the surface of sulfonated cellulose nanofibers, preventing agglomeration and promoting dispersion, improving the network, optimizing stress transmission, and making the material have high torque and good flexibility. Detailed Implementation

[0021] raw material Nitrile rubber, model NBR3345, with an acrylonitrile content of 33.0 wt%, was purchased from Ningbo Shunze Rubber Co., Ltd. Polyurethane, specifically solvent-free polyurethane resin, was purchased from Huafeng Group Co., Ltd. Sulfonated cellulose nanocrystals, with a diameter of 4–30 nm and a length of 100–500 nm, were purchased from Qihong Technology Co., Ltd. Calcium lignosulfonate, sodium lignosulfonate, and magnesium lignosulfonate were all purchased from Shenyang Xingzhenghe Chemical Co., Ltd. Graphene oxide, model XF002-2, is a single-layer graphene oxide powder with a sheet diameter of 0.5-5 μm and a thickness of 0.8-1.2 nm, purchased from Jiangsu Xianfeng Nanomaterials Technology Co., Ltd. Antioxidant 1135, Antioxidant 1726, Antioxidant 245, and Antioxidant 168 were all purchased from Tianjin Lianlong New Materials Co., Ltd. Carbon fiber, a long fiber, type T300-3000, with a single filament fineness of 3000 denier, a yarn count of 198 Tex, and a density of 1.76 g / cm³. 2 Purchased from Toray Industries Group; Aramid fiber, specifically meta-aramid filament, was purchased from Suzhou Hengsian Protective Technology Co., Ltd. Natural rubber, grade SCR 5, purchased from Hainan Natural Rubber Industry Group Co., Ltd. Butadiene rubber, grade BR 9000, was purchased from Sinopec Yanshan Petrochemical Company; γ-aminopropyltriethoxysilane, γ-aminopropyltrimethoxysilane, and γ-aminopropylmethyldiethoxysilane were all purchased from Nanjing Shuguang New Materials Co., Ltd. Anhydrous ethanol and ammonium bicarbonate were both sourced from commercially available sources.

[0022] Preparation Example 1 A pretreated graphene oxide is prepared by the following method: 1.2 kg of graphene oxide was added to 100 L of a mixed solvent of anhydrous ethanol and water (volume ratio of anhydrous ethanol to water was 9:1) and dispersed at 8000 rpm for 15 min to obtain a graphene oxide suspension.

[0023] 24 g of γ-aminopropyltriethoxysilane was dissolved in 2 L of ethanol and stirred at 200 rpm for 30 min to obtain an ethanol solution of γ-aminopropyltriethoxysilane coupling agent. The ethanol solution of γ-aminopropyltriethoxysilane coupling agent was added to the graphene oxide suspension at a rate of 20 mL / min while stirring at 300 rpm. The temperature was raised to 80 °C and maintained at this temperature for 12 h while stirring at 200 rpm.

[0024] After the reaction was completed, heating was stopped and the mixture was allowed to cool naturally to room temperature (25°C). The reaction product was then filtered, and the filter cake was washed four times alternately with anhydrous ethanol and deionized water. The washed filter cake was then placed in a vacuum drying oven and dried at 80°C for 24 hours to obtain a pretreated graphene oxide.

[0025] Preparation Example 2 A pretreated graphene oxide differs from Preparation Example 1 in that γ-aminopropyltrimethoxysilane is used in place of γ-aminopropyltriethoxysilane by an equal mass, while the rest is the same as in Preparation Example 1.

[0026] Preparation Example 3 A pretreated graphene oxide differs from Preparation Example 1 in that γ-aminopropylmethyldiethoxysilane is used in place of γ-aminopropyltriethoxysilane by an equal mass, while the rest is the same as Preparation Example 1.

[0027] Preparation Example 4 A modified carbon fiber, the preparation method of which is as follows: The carbon fiber precursor is passed through a 450℃ muffle furnace at a speed of 0.5 m / min and held for 2 min to remove the slurry from the surface.

[0028] The desized carbon fiber was used as the anode, immersed in an electrolyte solution, and connected to the positive terminal of a DC power supply. Graphite was used as the cathode, the electrolyte was a 1 mol / L NH4HCO3 solution, and the current density was 2 A / m. 2 After processing for 2 minutes, the electrolytically oxidized carbon fibers are washed with deionized water to remove surface electrolyte residues. After washing, they are sent to a drying oven at 100°C for 30 minutes to remove moisture, thus obtaining modified carbon fibers.

[0029] Preparation Example 5 A pretreated aramid fiber is prepared by means of the following method: the aramid fiber is placed in a low-temperature plasma treatment machine for plasma treatment, wherein the power of the low-temperature plasma treatment machine is 200W, the treatment gas is air, the gas flow rate is 50sccm, the vacuum degree of the chamber is 40Pa, and the treatment time is 5min, thereby obtaining the pretreated aramid fiber.

[0030] Example 1 A high-torque, high-flexibility transmission belt comprises an outer rubber layer, a middle reinforcing layer, and an inner rubber layer. The outer rubber layer is prepared from the following components by mass: 70 kg of nitrile rubber, 30 kg of polyurethane, 7.8 kg of sulfonated cellulose nanofibers, 1.2 kg of calcium lignosulfonate, 1 kg of pretreated graphene oxide, and 1.5 kg of antioxidant 1135. The middle reinforcing layer is prepared from the following components by mass: 70 kg of modified carbon fiber and 30 kg of pretreated aramid fiber. The inner rubber layer is prepared from the following components by mass: 80 kg of natural rubber and 40 kg of butadiene rubber. The pretreated graphene oxide is derived from Preparation Example 1, the modified carbon fiber is derived from Preparation Example 4, and the pretreated aramid fiber is derived from Preparation Example 5.

[0031] Its preparation method is as follows: S1: Sulfonated cellulose nanofibers were ultrasonically treated in 100L of deionized water at 500W for 60min to obtain a sulfonated cellulose nanofiber suspension. Calcium lignin sulfonate was added to 80L of deionized water to obtain a calcium lignin sulfonate solution. The sulfonated cellulose nanofiber suspension was added to the calcium lignin sulfonate solution at a rate of 100mL / min while stirring at 200rpm. After addition, stirring was continued for 30min. Spray drying was then performed at an atomization pressure of 0.4MPa, a feed pump rate of 20mL / min, and an inlet temperature of [missing information]. At a temperature of 200℃ and an outlet temperature of 80℃, a mixture of sulfonated cellulose nanofibers and calcium lignosulfonate powder was obtained. Nitrile rubber and polyurethane were plasticized separately in a two-roll mill at a roller temperature of 45℃ and a roller gap of 0.5mm for 1 minute. The mixture of sulfonated cellulose nanofibers and calcium lignosulfonate powder, antioxidant 1135, and pretreated graphene oxide were added and mixed for 2 minutes. The mixture was then added again and mixed for 3 minutes. The rubber was discharged at a discharge temperature of 90℃. The rubber was then passed through a thin mill 3 times and rolled 5 times. The roller gap was adjusted to 5mm before sheeting to obtain the outer layer rubber. S2: Add natural rubber and butadiene rubber to the internal mixer, mix for 3 minutes, discharge the rubber to the open mill, open mill roller temperature 60℃, pass through the thin mill 5 times, sheet out, let it stand for 24 hours to cure, and obtain the inner layer rubber. S3: Woven using a warp and weft knitting machine, with modified carbon fiber used entirely in the warp direction and pretreated aramid fiber used in the weft direction. The warp knitting density is 10 threads / cm, and the weft density is 6 threads / cm, resulting in a plain weave fabric with an areal density of 900g / m². 2 ; S4: Place the fabric between the outer and inner rubber layers, place it in a vulcanizing mold, vulcanize it at a mold temperature of 160℃ and a vulcanization pressure of 15MPa for 25 minutes, hold the pressure and let it cool naturally to 60℃, release the pressure and take out the belt blank, and let it stand at room temperature (25℃) for 24 hours to obtain a high-torque and high-flexibility transmission belt.

[0032] Comparative Example 1 A high-torque, high-flexibility transmission belt differs from Example 1 in that it does not contain sulfonated cellulose nanofibers, while the rest is the same as Example 1.

[0033] Comparative Example 2 A high-torque, high-flexibility transmission belt differs from Example 1 in that it does not contain calcium lignosulfonate, while the rest is the same as Example 1.

[0034] Example 2 A high-torque, high-flexibility transmission belt differs from Example 1 in that it contains 7.5 kg of sulfonated cellulose nanofibers and 1.5 kg of calcium lignosulfonate, while the rest of the components are the same as in Example 1.

[0035] Example 3 A high-torque, high-flexibility transmission belt differs from Example 1 in that it contains 8 kg of sulfonated cellulose nanofibers and 1 kg of calcium lignin sulfonate, while the rest of the components are the same as in Example 1.

[0036] Example 4 A high-torque, high-flexibility transmission belt differs from Example 1 in that it contains 7 kg of sulfonated cellulose nanofibers and 2 kg of calcium lignin sulfonate, while the rest of the components are the same as in Example 1.

[0037] Example 5 A high-torque, high-flexibility transmission belt differs from Example 1 in that it contains 8 kg of sulfonated cellulose nanofibers and 0.5 kg of calcium lignosulfonate, while the rest of the components are the same as in Example 1.

[0038] Example 6 A high-torque, high-flexibility transmission belt differs from Example 1 in that sodium lignosulfonate is used instead of calcium lignosulfonate by mass, while the rest is the same as in Example 1.

[0039] Example 7 A high-torque, high-flexibility transmission belt differs from Example 1 in that magnesium lignosulfonate is used instead of calcium lignosulfonate, while the rest is the same as in Example 1.

[0040] Example 8 A high-torque, high-flexibility transmission belt differs from Example 1 in that the pretreated graphene oxide is derived from Preparation Example 2, while the rest is the same as in Example 1.

[0041] Example 9 A high-torque, high-flexibility transmission belt differs from Example 1 in that the pretreated graphene oxide is derived from Preparation Example 3, while the rest is the same as Example 1.

[0042] Example 10 A high-torque, high-flexibility transmission belt differs from Example 1 in that it uses graphene oxide of equal mass instead of pretreated graphene oxide, while the rest is the same as in Example 1.

[0043] Example 11 A high-torque, high-flexibility transmission belt differs from Example 1 in that antioxidant 1135 is replaced by an equal mass of antioxidant 1726, while the rest is the same as in Example 1.

[0044] Example 12 A high-torque, high-flexibility transmission belt differs from Example 1 in that antioxidant 245 is used in place of antioxidant 1135 by mass, while the rest is the same as in Example 1.

[0045] Example 13 A high-torque, high-flexibility transmission belt differs from Example 1 in that antioxidant 1135 is replaced by antioxidant 168 by mass, while the rest is the same as in Example 1.

[0046] Example 14 A high-torque, high-flexibility transmission belt differs from Example 1 in that it uses carbon fiber of equal mass instead of modified carbon fiber, while the rest is the same as Example 1.

[0047] Example 15 A high-torque, high-flexibility transmission belt differs from Example 1 in that it uses aramid fibers of equal mass instead of pretreated aramid fibers, while the rest is the same as Example 1.

[0048] Example 16 A high-torque, high-flexibility transmission belt differs from Example 1 in that: the outer rubber layer comprises the following components by mass: 60 kg of nitrile rubber, 20 kg of polyurethane, sulfonated cellulose nanofibers, 3.9 kg of calcium lignosulfonate, 0.6 kg of calcium lignosulfonate, 0.5 kg of pretreated graphene oxide, and 1 kg of antioxidant 1135; the intermediate reinforcing layer comprises the following components by mass: 50 kg of modified carbon fiber and 20 kg of pretreated aramid fiber; the inner rubber layer comprises the following components by mass: 70 kg of natural rubber and 30 kg of butadiene rubber, with the remaining components being the same as in Example 1.

[0049] Example 17 A high-torque, high-flexibility transmission belt differs from Example 1 in that: the outer rubber layer comprises the following components by mass: 80 kg of nitrile rubber, 40 kg of polyurethane, 11.7 kg of sulfonated cellulose nanofibers, 1.8 kg of calcium lignosulfonate, 1.5 kg of pretreated graphene oxide, and 2 kg of antioxidant 1135; the intermediate reinforcing layer comprises the following components by mass: 80 kg of modified carbon fiber and 40 kg of pretreated aramid fiber; the inner rubber layer comprises the following components by mass: 90 kg of natural rubber and 50 kg of butadiene rubber, with the remaining components being the same as in Example 1.

[0050] Examples 1-17 and Comparative Examples 1-2 were tested using the following methods: According to GB / T 3690-2017 "Test Method for Tensile Strength, Elongation at Break and Elongation at Reference Force of Fabric Core Conveyor Belts of Full Thickness", the tensile properties of Examples 1-17 and Comparative Examples 1-2 were tested. The sample size was 300mm×25mm×10mm. The test machine stretched the sample at a constant speed of 100mm / min until it broke and the maximum tensile force was recorded. The tensile strength and elongation at break were calculated. The higher the tensile strength and elongation at break, the greater the torque that can be transmitted. The test results are shown in Table 1.

[0051] According to Appendix A of GB / T 12736-2021 "Static Test Method for Determination of Strength of Mechanical Joints of Conveyor Belts", the repeated bending life of Examples 1-17 and Comparative Examples 1-2 was tested. The sample size was 300mm×25mm×10mm, the pulley diameter was 100mm, the applied tension was 100N, and the bending frequency was 1.0Hz. Repeated bending tests were carried out. When any of the following conditions occurred, such as fracture, crack, delamination, or peeling, the number of bending was recorded. The more bending times, the better the flexibility. The test results are shown in Table 1.

[0052] Table 1. Test results of Examples 1-17 and Comparative Examples 1-2 Tensile strength (MPa) Elongation at break (%) Bending life (thousands) Example 1 30 400 100 Example 2 27 370 88 Example 3 27.5 375 89 Example 4 22 320 75 Example 5 20 300 70 Example 6 25.5 365 90 Example 7 24.5 358 89 Example 8 29.5 395 99 Example 9 29.5 395 99 Example 10 24 340 78 Example 11 29.8 398 99 Example 12 29.8 398 100 Example 13 26 360 85 Example 14 23 330 76 Example 15 24 340 77 Example 16 23 335 75 Example 17 24 330 78 Comparative Example 1 19 300 70 Comparative Example 2 18 300 68 Based on Table 1, Examples 1-17 and Comparative Examples 1-2 were analyzed, and the analysis is as follows: Compared with Example 1, the tensile strength, elongation at break and bending life of the transmission belt in Example 1 are all greater than those of the transmission belt in Example 1.

[0053] Compared to Comparative Example 1, Example 1 incorporates sulfonated cellulose nanofibers. The surface of sulfonated cellulose nanofibers has a large number of hydroxyl groups, which can form hydrogen bond networks with the polar groups of nitrile rubber and polyurethane, anchoring the rubber molecular chains to form physical cross-linking points. When subjected to force, stress is efficiently transferred to the whiskers, improving the material's torque and flexibility. Therefore, the addition of sulfonated cellulose nanofibers is necessary.

[0054] Compared with Example 1 and Comparative Example 2, the tensile strength, elongation at break and bending life of the transmission belt in Example 1 are all greater than those of the transmission belt in Comparative Example 2.

[0055] Compared to Comparative Example 2, Example 1 added lignin sulfonate; lignin sulfonate has an amphiphilic structure, and its hydrophobic aromatic ring skeleton has good compatibility with rubber and can be entangled by van der Waals forces. The hydrophilic sulfonic acid groups can form ionic bonds or hydrogen bonds with the polar regions of rubber, improving interfacial compatibility. Moreover, its flexible chain can absorb and dissipate energy, preventing crack initiation and propagation, and toughening and crack suppression; therefore, the addition of lignin sulfonate is necessary.

[0056] Comparing Examples 1 and Examples 2-5, the tensile strength, elongation at break, and flexural life of the transmission belt in Example 1 are all greater than those of the transmission belts in Examples 2-5; and the tensile strength, elongation at break, and flexural life of the transmission belts in Examples 2-3 are all greater than those of the transmission belts in Examples 4-5.

[0057] Compared to Examples 4-5, the mass ratio of sulfonated cellulose nanofibers to calcium lignin sulfonate in Examples 1-3 is (5-8):1. This ratio allows the reinforcing agent to be more evenly dispersed in the rubber and to have better interfacial bonding, thereby improving the torque transmission efficiency of the conveyor belt, avoiding local stress concentration, and maintaining flexibility. Therefore, a mass ratio of sulfonated cellulose nanofibers to calcium lignin sulfonate of (5-8):1 is preferred.

[0058] Comparing Example 1 and Examples 6-7, the tensile strength, elongation at break, and flexural life of the transmission belt in Example 1 are close to those of the transmission belts in Examples 6-7.

[0059] Compared to Examples 6-7, the lignin sulfonate in Example 1 is calcium lignin sulfonate. Calcium ions can form reversibly broken and recombined weak ionic bonds with the polar groups of rubber, dissipating energy and improving toughness and fatigue resistance. In addition, the calcium sulfonate group has good thermal stability, maintaining dispersion and preventing degradation. The calcium ion radius is moderate, which can uniformly crosslink without affecting fluidity, making the transmission belt stable under high pressure and less prone to cracking after repeated bending. Therefore, calcium lignin sulfonate is the preferred choice for lignin sulfonate.

[0060] Comparing Examples 1 and Examples 8-10, the tensile strength, elongation at break, and flexural life of the transmission belt in Example 1 are close to those of the transmission belts in Examples 8-9; and the tensile strength, elongation at break, and flexural life of the transmission belts in Examples 8-9 are greater than those of the transmission belt in Example 10.

[0061] Compared to Example 10, the graphene oxide in Examples 1 and 8-9 was treated with an aminosilane coupling agent. After treatment with the aminosilane coupling agent, the graphene oxide is more uniformly dispersed in the rubber matrix, preventing agglomeration, improving the interfacial stress transmission efficiency, enhancing the interfacial adhesion with the rubber material, increasing the modulus and tensile strength of the outer rubber layer, and improving the torque capacity and flexibility of the transmission belt. Therefore, the treatment of graphene oxide with an aminosilane coupling agent is superior.

[0062] Comparing Example 1 and Examples 11-13, the tensile strength, elongation at break, and flexural life of the transmission belt in Example 1 are close to those of the transmission belts in Examples 11-12, while the tensile strength, elongation at break, and flexural life of the transmission belts in Examples 11-12 are greater than those of the transmission belts in Example 13.

[0063] Compared to Example 13, the antioxidants in Examples 1 and 11-12 are all phenolic antioxidants. When the transmission belt is heated during high-torque operation with phenolic antioxidants, the antioxidants provide hydrogen atoms through their phenolic hydroxyl groups to capture free radicals generated during the thermo-oxidative aging process of rubber, interrupting the oxidation chain reaction, thereby slowing down the breakage of rubber molecular chains and changes in crosslinking density, and avoiding the oxidation reaction of other components during the preparation process, which would lead to a decline in performance. Therefore, using phenolic antioxidants is preferable.

[0064] Comparing Example 1 and Example 14, the tensile strength, elongation at break, and flexural life of the transmission belt in Example 1 are all greater than those of the transmission belt in Example 14.

[0065] Compared to Example 14, the carbon fiber in Example 1 underwent oxidative modification. Oxidation introduces oxygen-containing functional groups such as carboxyl and hydroxyl groups onto the surface of the carbon fiber, thereby increasing its surface energy and polarity, improving its wettability and affinity with the rubber matrix, enhancing interfacial adhesion, enabling efficient stress transmission, reducing slippage, and improving the stiffness, strength, torque, and flexibility of the transmission belt. Therefore, oxidative modification of carbon fiber is superior.

[0066] Comparing Example 1 and Example 15, the tensile strength, elongation at break, and flexural life of the transmission belt in Example 1 are all greater than those of the transmission belt in Example 15.

[0067] Compared to Example 15, the aramid fibers in Example 1 underwent low-temperature plasma treatment. Low-temperature plasma treatment introduces polar functional groups (such as hydroxyl or carboxyl groups), increases the surface roughness of the aramid fibers, removes contaminants, improves the interfacial bonding strength between the aramid fibers and the rubber matrix, and enables stress to be transferred more effectively from the rubber to the fibers, thereby improving the flexibility of the transmission belt and reducing the risk of breakage under high torque. Therefore, low-temperature plasma treatment of aramid fibers is superior.

[0068] Comparing Example 1 and Examples 16-17, the tensile strength, elongation at break, and flexural life of the transmission belt in Example 1 are all greater than those of the transmission belts in Examples 16-17.

[0069] Compared to Examples 16-17, the mass ratio of nitrile rubber, polyurethane, sulfonated cellulose nanofibers, pretreated graphene oxide, and antioxidant 1135 in Example 1 is 70:30:8.75:1.25:1.5; the mass ratio of modified carbon fiber and pretreated aramid fiber in the intermediate reinforcing layer is 70:30; and the mass ratio of natural rubber and butadiene rubber in the inner rubber layer is 80:40. Therefore, the mass ratio of nitrile rubber, polyurethane, sulfonated cellulose nanofibers, pretreated graphene oxide, and antioxidant 1135 in the outer rubber layer (70:30:8.75:1.25:1.5), the mass ratio of modified carbon fiber and pretreated aramid fiber in the intermediate reinforcing layer (70:30), and the mass ratio of natural rubber and butadiene rubber in the inner rubber layer (80:40) is superior.

[0070] This specific embodiment is merely an explanation of the present invention and is not intended to limit the invention. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they are within the scope of protection claimed by the present invention.

Claims

1. A high torque high flexibility drive belt characterized in that, The tire is composed of an outer rubber layer, a middle reinforcing layer and an inner rubber layer, The outer rubber layer comprises the following components in parts by weight: nitrile rubber 60-80 parts, polyurethane 20-40 parts, antioxidant 1-2 parts, reinforcing agent 5-15 parts, the reinforcing agent comprising sulfonated cellulose nanowhiskers, lignosulfonate and graphene oxide; The middle reinforcing layer comprises the following components in parts by weight: carbon fiber 50-80 parts, aramid fiber 20-40 parts; The inner rubber layer comprises the following components in parts by weight: natural rubber 70-90 parts and butadiene rubber 30-50 parts.

2. The high-torque, high-flexibility transmission belt of claim 1, wherein, The mass ratio of the sulfonated cellulose nanowhiskers and the lignosulfonate is (5-8):

1.

3. The high-torque, high-flexibility transmission belt of claim 1, wherein, The lignosulfonate is calcium lignosulfonate.

4. The high-torque, high-flexibility transmission belt of claim 1, wherein, The graphene oxide is treated with an amino silane coupling agent.

5. The high torque, high flexibility power transmission belt of claim 1, wherein, The antioxidant is a phenolic antioxidant.

6. The high torque, high flexibility power transmission belt of claim 1, wherein, The carbon fiber is treated with an oxidation modification.

7. The high-torque, high-flexibility transmission belt of claim 1, wherein, The aramid fiber is treated with a low-temperature plasma.

8. A method of manufacturing the high-torque and high-flexibility transmission belt according to any one of claims 1 to 7, characterized by, The method comprises the following steps: S1: mixing nitrile rubber, polyurethane, graphene oxide, reinforcing agent and antioxidant to obtain an outer rubber layer; S2: mixing natural rubber and butadiene rubber to obtain an inner rubber layer; S3: weaving the carbon fiber and the aramid fiber into a plain fabric; S4: pressing the plain fabric on the inner rubber layer, covering the outer rubber layer on the plain fabric, hot-pressing to obtain a tire band, and cooling and setting the tire band.