Carbon fiber rim of bicycle and preparation method of fiber yarn material for carbon fiber rim

Abstract

The invention provides a bicycle carbon fiber rim and a preparation method of a fiber yarn material for the bicycle carbon fiber rim, and belongs to the technical field of bicycle parts. The material is composed of pretreated carbon fibers and a modified glue solution. The modified glue solution comprises 80-120 parts of epoxy resin, 30-40 parts of a 4, 4-diaminobenzene sulfone curing agent, 10-20 parts of a polybutadiene rubber toughening agent, 2-4 parts of a bonding accelerant, 1-3 parts of an anti-hydrolysis agent, 2-5 parts of an acid and alkali resistant aid and 1-5 parts of micron-sized silicon dioxide; according to the preparation technology, the fiber yarn material for the rim is prepared through the technologies of fiber yarn surface activating treatment, modified glue solution step-by-step preparation, gradient gluing and pre-curing, high-pressure compounding and step curing, surface anti-corrosion layer sealing and the like, the corrosion resistance is greatly improved, the ultra-high temperature resistance is excellent, and the retention rate of the tensile strength at 200 DEG C exceeds 80%; the prepared wheel rim is outstanding in mechanical property, has no obvious damage after 1000km in actual road condition test, is small in rolling resistance change, and effectively solves the problems that in an original scheme, a glue solution is easy to separate from cellosilk, and the environment resistance is poor.

Description

Technical Field

[0001] This invention belongs to the field of bicycle parts technology, specifically relating to a carbon fiber bicycle rim and a method for preparing the fiber material for the rim. Background Technology

[0002] With the continuous advancement of materials science, carbon fiber composite materials have gradually entered the bicycle manufacturing field due to their superior performance. Carbon fiber is a special fiber composed of carbon elements, which has outstanding characteristics of high strength, high modulus, and lightweight. Its density is much lower than that of steel and aluminum alloys, while its strength can reach or even exceed that of traditional metal materials. Applying carbon fiber materials to wheel rim manufacturing can significantly reduce the weight of the wheel rim while ensuring that the wheel rim has sufficient structural strength and rigidity to effectively cope with various loads and impacts during riding. This perfect combination of lightweight and high strength has led to the widespread use of carbon fiber rims in high-end bicycles. For professional riders and high-end users seeking ultimate performance, the advantages of carbon fiber rims are obvious: on the one hand, the reduced weight improves the bicycle's acceleration and climbing ability, making riding more effortless and efficient; on the other hand, the excellent rigidity ensures the stability of the rim under high-speed rotation and complex road conditions, improving riding safety and handling precision. Therefore, carbon fiber rims have become an important symbol of high-end bicycles in terms of overall performance and technological sophistication, driving the development of bicycles towards lighter and higher performance. Carbon fiber rims are widely used in high-end bicycles due to their lightweight and high strength characteristics, but existing technology has many shortcomings: For example, Chinese patent CN109988399A describes a fiber material and preparation process for bicycle wheel rims. It uses a composite fiber material composed of carbon fiber or aramid fiber filaments and an adhesive solution to bond the fiber filaments. The wheel rim made from this material can withstand temperatures above 150°C, solving the problem of insufficient strength of traditional materials at high temperatures. The existing technologies for bicycle rims and their fiber materials, as represented by the aforementioned patents, have limitations in their application scenarios. Under prolonged high-intensity braking or long-term high-frequency stress, cracks may appear in the cross-section of the fiber and the adhesive, affecting the performance and service life of the rim. Furthermore, in high-humidity or acidic / alkaline environments, components such as epoxy resin and curing agents in the adhesive may undergo hydrolysis or chemical corrosion, affecting the adhesion stability between the fiber and the adhesive, thereby reducing the overall strength of the rim. Summary of the Invention

[0003] This invention addresses the problems of the prior art by providing a method for preparing carbon fiber bicycle rims and fiber materials for the rims.

[0004] To achieve the above objectives, the technical solution adopted in this application is as follows: A carbon fiber bicycle rim includes rim filaments, the raw material composition of which by weight is as follows: 50-80 parts of pretreated filaments and 20-50 parts of modified adhesive; wherein, the pretreated filaments include carbon fibers. The modified adhesive has the following raw material composition by weight: 80-120 parts epoxy resin, 30-40 parts 4,4-diaminophenyl sulfone curing agent, 10-20 parts polybutadiene rubber toughening agent, 2-4 parts adhesion promoter, 1-3 parts anti-hydrolysis agent, 2-5 parts acid and alkali resistant additive, and 1-5 parts micron-sized silica.

[0005] Preferably, the adhesion promoter is γ-aminopropyltriethoxysilane; the anti-hydrolysis agent is carbodiimide; and the acid and alkali resistant additive is nano-titanium dioxide with a particle size controlled at 1-3 μm.

[0006] Preferably, the epoxy value of the epoxy resin is controlled at 0.86-0.91 eq. / 100g.

[0007] A method for preparing carbon fiber filament material for bicycle rims includes the following processes: surface activation treatment of filaments, stepwise preparation of modified adhesive, gradient coating and pre-curing, high-pressure lamination and step curing, and surface anti-corrosion sealing layer.

[0008] Preferably, the specific steps of the fiber surface activation treatment are as follows: Degreasing: Place the fiber in 75% ethanol and ultrasonically clean for 20 minutes to remove surface oil. Plasma etching: The degreased fibers are fed into a low-pressure radio frequency plasma treatment system and treated for 5-8 minutes with oxygen as the gas source at a power of 300-500W. Coupling agent impregnation: The plasma-etched fiber filaments were immersed in a 1% γ-aminopropyltriethoxysilane ethanol solution and soaked at 30°C for 30 min; then dried at 80°C for 1 h to obtain the pretreated fiber filaments; the volume ratio of γ-aminopropyltriethoxysilane to anhydrous ethanol in the 1% γ-aminopropyltriethoxysilane ethanol solution was 1:10.

[0009] Preferably, the modified adhesive solution is prepared in the following steps: Epoxy resin premixing: Take epoxy resin, add anti-hydrolysis agent, and put it into a high-speed mixer and stir for 15 minutes at 60℃ and 1000rpm; to obtain phase A; Additive dispersion: The dried 4,4-diaminophenyl sulfone curing agent and polybutadiene rubber toughening agent were poured into another high-speed mixer and stirred at 500 rpm at 70°C to preheat and mix the curing agent and toughening agent. Then, while maintaining the temperature, the speed was increased to 800 rpm and nano-titanium dioxide was added, and stirring continued for 10 minutes. Finally, while maintaining the temperature, the speed was increased to 1200 rpm and micron-sized silica was added, and stirring continued for 15 minutes to obtain phase B. Composite mixing: Add the above phase A and phase B to the bonding accelerator and feed them into another high-speed mixer equipped with shearing and grinding. Shear and grind at 75℃ and 1600rpm for 25-40min to obtain the modified adhesive.

[0010] Preferably, the gradient coating and pre-curing steps are as follows: Underlayer coating: Apply the modified adhesive solution at a rate of 20-190 g / m2 onto 80-150 μm release paper, pre-bake at 45℃ for 8 min to form a preliminary adhesive layer on the release paper; Reinforcing layer coating: A layer of concentrated adhesive containing 5% nano titanium dioxide is coated on the bottom adhesive and pre-baked at 50°C for 5 minutes to obtain two layers of gradient coated release paper.

[0011] Preferably, the high-pressure composite and stepped curing processes are as follows: Composite process: Two layers of gradient-coated release paper are symmetrically placed between two pressure rollers, and then the pretreated fiber filaments are laid flat between the two layers of gradient-coated release paper; then the composite process is carried out at 110℃ with a pressure of 35GPa / cm2 and a pressing speed of 3-15m / min to obtain fiber-adhesive composite preform; Step curing: The fiber-adhesive composite preform is fed into a step curing oven and cured at 120°C for 1.5 hours, then heated to 150°C for 1 hour; finally cooled to 90°C and held for 1 hour to obtain the fiber material for bicycle wheels.

[0012] Preferably, the specific steps for the surface anti-corrosion sealing layer are as follows: Cleaning: Rinse the surface of the composite material with deionized water, and then dry it in an oven at 60°C; Coating and sealing: Spray a fluorocarbon resin coating onto the surface of the cleaned and dried rim fiber material, and then place it in a curing oven at 120°C for 40 minutes to achieve a surface anti-corrosion sealing layer for the fiber material.

[0013] Preferably, the fluorocarbon resin coating has a thickness of 10-15 μm.

[0014] Compared with the prior art, the advantages and positive effects of the present invention are as follows: This application discloses a method for preparing a carbon fiber bicycle rim and its rim fiber material. The material composition consists of pretreated carbon fiber and a modified adhesive. The modified adhesive includes 80-120 parts epoxy resin, 30-40 parts 4,4-diaminophenyl sulfone curing agent, 10-20 parts polybutadiene rubber toughening agent, 2-4 parts adhesion promoter, 1-3 parts anti-hydrolysis agent, 2-5 parts acid and alkali resistant additives, and 1-5 parts micron-sized silica. In terms of the preparation process, the rim fiber material, prepared through fiber surface activation treatment, stepwise preparation of the modified adhesive, gradient coating and pre-curing, high-pressure lamination and step curing, and surface anti-corrosion sealing, exhibits significantly improved corrosion resistance and excellent ultra-high temperature resistance, with a tensile strength retention rate exceeding 80% at 200℃. The resulting rim demonstrates outstanding mechanical properties, showing no significant damage after 1000km in actual road condition testing, with minimal change in rolling resistance. This effectively solves the problems of easy separation between the adhesive and fiber and poor environmental resistance in the original solution. Detailed Implementation

[0015] To better understand the above-mentioned objectives, features, and advantages of the present invention, the present invention will be further described below with reference to embodiments. It should be noted that, unless otherwise specified, the embodiments and features described in these embodiments can be combined with each other.

[0016] Numerous specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways than those described herein, and therefore the invention is not limited to the specific embodiments disclosed in the following specification.

[0017] This application discloses a carbon fiber bicycle rim comprising rim filaments, wherein the raw material composition of the rim filaments by weight is as follows: 50-80 parts of pretreated filaments and 20-50 parts of modified adhesive; wherein the pretreated filaments comprise carbon fiber. The modified adhesive has the following raw material composition by weight: 80-120 parts epoxy resin, 30-40 parts 4,4-diaminophenyl sulfone curing agent, 10-20 parts polybutadiene rubber toughening agent, 2-4 parts adhesion promoter, 1-3 parts anti-hydrolysis agent, 2-5 parts acid and alkali resistant additive, and 1-5 parts micron-sized silica. The adhesion promoter is γ-aminopropyltriethoxysilane; the anti-hydrolysis agent is carbodiimide; the acid and alkali resistant additive is nano titanium dioxide, and the particle size of nano titanium dioxide is controlled at 1-3μm. The epoxy value of the epoxy resin is controlled at 0.86-0.91 eq. / 100g.

[0018] The epoxy resin is DER 331 purchased from Dow Chemical; the 4,4-diaminophenyl sulfone curing agent has CAS number 80-08-0; the polybutadiene rubber toughening agent is YT-3156 purchased from Jinghan New Materials; the adhesion accelerator is KH-550 purchased from Dewar Chemical; and the anti-hydrolysis agent is HyMax-500 purchased from Nanjing Baitong.

[0019] A method for preparing carbon fiber filament material for bicycle rims includes the following processes: surface activation treatment of filaments, stepwise preparation of modified adhesive, gradient coating and pre-curing, high-pressure lamination and step-curing, and surface anti-corrosion sealing layer. The specific steps for the surface activation treatment of the fibers are as follows: Degreasing: Place the fiber in 75% ethanol and ultrasonically clean for 20 minutes to remove surface oil. Plasma etching: The degreased fibers are fed into a low-pressure radio frequency plasma treatment system and treated for 5-8 minutes at a power of 300-500W with oxygen as the gas source. The purpose of this step is to introduce active groups such as hydroxyl and carboxyl groups to enhance the reactivity between the fibers and the adhesive. Coupling agent impregnation: The plasma-etched fiber filaments were immersed in a 1% γ-aminopropyltriethoxysilane ethanol solution at 30°C for 30 min; then dried at 80°C for 1 h to form a chemically bonded transition layer; the γ-aminopropyltriethoxysilane was purchased from Nanjing Shuguang Chemical Co., Ltd.; the pretreated fiber filaments were obtained; the volume ratio of γ-aminopropyltriethoxysilane to anhydrous ethanol in the 1% γ-aminopropyltriethoxysilane ethanol solution was 1:10. The specific steps for preparing the modified adhesive solution are as follows: Epoxy resin premixing: Epoxy resin was added to an anti-hydrolysis agent and fed into a high-speed mixer, where it was stirred for 15 minutes at 60°C and 1000 rpm; the high-speed mixer was a Shanghai Edong Electromechanical ME720 powder suction type high shear emulsifier; phase A was obtained. Additive dispersion: The dried 4,4-diaminophenyl sulfone curing agent and polybutadiene rubber toughening agent were poured into another high-speed mixer and stirred at 500 rpm at 70°C to preheat and mix the curing agent and toughening agent. Then, while maintaining the temperature, the speed was increased to 800 rpm, and nano-titanium dioxide was added in three batches, with a 1-minute interval between each addition to avoid agglomeration. Stirring continued for 10 minutes. Finally, while maintaining the temperature, the speed was increased to 1200 rpm, and micron-sized silica was added and stirred for 15 minutes. During this time, the system was checked through an observation window to confirm that there was no obvious particle sedimentation or agglomeration. Phase B was obtained. Composite mixing: Add the above phase A and phase B to the bonding accelerator and feed them into another high-speed mixer equipped with shearing and grinding. Shear and grind at 75℃ and 1600rpm for 25-40min to obtain the modified adhesive solution. The specific steps for gradient adhesive application and pre-curing are as follows: Underlayer coating: Apply the modified adhesive solution at a rate of 20-190 g / m2 onto 80-150 μm release paper, pre-bake at 45℃ for 8 min to form a preliminary adhesive layer on the release paper; Reinforcing layer coating: A layer of concentrated adhesive containing 5% nano titanium dioxide is coated on the bottom adhesive and pre-baked at 50℃ for 5 minutes to enhance environmental resistance and obtain a two-layer gradient coated release paper. The specific steps of high-pressure composite and stepped curing are as follows: Composite process: Two layers of gradient-coated release paper are symmetrically placed between two pressure rollers. Pre-treated fiber filaments are then laid flat between the two layers of gradient-coated release paper. The composite process is then carried out at 110℃ with a pressure of 35 GPa / cm², and a pressing speed of 3-15 m / min. This process promotes the full cross-linking of the epoxy resin, curing agent, and surface-active groups of the fiber filaments in the adhesive solution, forming a dense and stable three-dimensional network structure. This enhances the adhesion strength between the adhesive solution and the fiber filaments, while also improving the material's environmental resistance and impact resistance, thus preparing it for subsequent processing. The resulting fiber-adhesive composite preform is then obtained. Step curing: The fiber-adhesive composite preform is fed into a step curing oven and cured at 120°C for 1.5 hours, then heated to 150°C for 1 hour; finally, it is cooled to 90°C and held for 1 hour to promote full cross-linking of the adhesive and the surface active groups of the fiber, thus obtaining the fiber material for wheel rims. The specific steps for applying the surface anti-corrosion sealing layer are as follows: Cleaning: Rinse the surface of the composite material with deionized water, and then dry it in an oven at 60°C; Coating and Sealing: A fluorocarbon resin coating is sprayed onto the cleaned and dried surface of the rim fiber material, followed by curing at 120℃ for 40 minutes in a curing oven. This forms a physical barrier against water and acid / alkali corrosion, achieving a surface anti-corrosion sealing layer for the rim fiber material. The fluorocarbon resin coating thickness is 10-15 μm. Rim materials prepared with the anti-corrosion sealing layer retain 92% of their adhesion strength after immersion in 85% humidity for 72 hours; after immersion in 5% HCl or NaOH solution for 72 hours, the erosion depth is <1 μm; and in simulated rough road conditions, there is no separation between the modified adhesive and the pretreated fibers.

[0020] Example 1 describes a carbon fiber bicycle rim, with the following raw material composition: the pretreated fiber filaments weigh 600g, and the modified adhesive weighs 400g; wherein the modified adhesive comprises 250g epoxy resin, 87.5g 4,4-diaminophenyl sulfone, 37.5g polybutadiene rubber, 7.5g adhesion promoter, 5g anti-hydrolysis agent, 7.5g nano-sized titanium dioxide, and 5g micron-sized silica; Example 1 describes a method for preparing carbon fiber filament material for bicycle rims, comprising the following processes: surface activation treatment of filaments, stepwise preparation of modified adhesive, gradient coating and pre-curing, high-pressure lamination and step-curing, and surface anti-corrosion sealing layer. The specific steps for the surface activation treatment of the fibers are as follows: Degreasing: Place the fiber in 75% ethanol and ultrasonically clean for 20 minutes to remove surface oil. Plasma etching: The degreased fibers are fed into a low-pressure radio frequency plasma treatment system and treated for 8 minutes at a power of 300-500W with oxygen as the gas source. The purpose of this step is to introduce active groups such as hydroxyl and carboxyl groups to enhance the reactivity between the fibers and the adhesive. Coupling agent impregnation: The plasma-etched fiber filaments were immersed in a 1% γ-aminopropyltriethoxysilane ethanol solution at 30°C for 30 min; then dried at 80°C for 1 h to form a chemically bonded transition layer; the γ-aminopropyltriethoxysilane was purchased from Nanjing Shuguang Chemical Co., Ltd.; the pretreated fiber filaments were obtained; the volume ratio of γ-aminopropyltriethoxysilane to anhydrous ethanol in the 1% γ-aminopropyltriethoxysilane ethanol solution was 1:10. The specific steps for preparing the modified adhesive solution are as follows: Epoxy resin premixing: Epoxy resin was added to an anti-hydrolysis agent and fed into a high-speed mixer, where it was stirred for 15 minutes at 60°C and 1000 rpm; the high-speed mixer was a Shanghai Edong Electromechanical ME720 powder suction type high shear emulsifier; phase A was obtained. Additive dispersion: The dried 4,4-diaminophenyl sulfone curing agent and polybutadiene rubber toughening agent were poured into another high-speed mixer and stirred at 500 rpm at 70°C to preheat and mix the curing agent and toughening agent. Then, while maintaining the temperature, the speed was increased to 800 rpm, and nano-titanium dioxide was added in three batches, with a 1-minute interval between each addition to avoid agglomeration. Stirring continued for 10 minutes. Finally, while maintaining the temperature, the speed was increased to 1200 rpm, and micron-sized silica was added and stirred for 15 minutes. During this time, the system was checked through an observation window to confirm that there was no obvious particle sedimentation or agglomeration. Phase B was obtained. Composite mixing: Add the above phase A and phase B to the bonding accelerator and feed them into another high-speed mixer equipped with shearing and grinding. Shear and grind at 75°C and 1600 rpm for 40 minutes to obtain the modified adhesive solution. The specific steps for gradient adhesive application and pre-curing are as follows: Underlayer coating: Apply the modified adhesive solution at a rate of 20-190 g / m2 onto 80-150 μm release paper, pre-bake at 45℃ for 8 min to form a preliminary adhesive layer on the release paper; Reinforcing layer coating: A layer of concentrated adhesive containing 5% nano titanium dioxide is coated on the bottom adhesive and pre-baked at 50℃ for 5 minutes to enhance environmental resistance and obtain a two-layer gradient coated release paper. The specific steps of high-pressure composite and stepped curing are as follows: Composite process: Two layers of gradient-coated release paper are symmetrically placed between two pressure rollers. Then, pre-treated fiber filaments are laid flat between the two layers of gradient-coated release paper. Subsequently, the composite process is carried out at 110℃ with a pressure of 35GPa / cm2 and a pressing speed of 14m / min. This process promotes the full cross-linking of epoxy resin, curing agent and surface active groups of fiber filaments in the adhesive solution, forming a dense and stable three-dimensional network structure. This enhances the adhesion strength between the adhesive solution and fiber filaments, while also improving the environmental resistance and impact resistance of the material, thus preparing it for subsequent processing. The resulting fiber-adhesive composite preform is obtained. Step curing: The fiber-adhesive composite preform is fed into a step curing oven and cured at 120°C for 1.5 hours, then heated to 150°C for 1 hour; finally, it is cooled to 90°C and held for 1 hour to promote full cross-linking of the adhesive and the surface active groups of the fiber, thus obtaining the fiber material for wheel rims. The specific steps for applying the surface anti-corrosion sealing layer are as follows: Cleaning: Rinse the surface of the composite material with deionized water, and then dry it in an oven at 60°C; Coating and sealing: A fluorocarbon resin coating is sprayed onto the surface of the cleaned and dried rim fiber material, and then placed in a curing oven at 120°C for 40 minutes to form a physical barrier on the rim fiber material to prevent water and acid and alkali corrosion, thereby achieving a surface anti-corrosion sealing layer on the fiber material, resulting in the surface anti-corrosion sealing layer for the rim fiber material of Example 1.

[0021] Example 2 differs from Example 1 in that it is a carbon fiber bicycle rim with the following raw material composition: the pretreated fiber filaments weigh 700g, and the modified adhesive weighs 300g; wherein, the modified adhesive comprises 180g epoxy resin, 64g 4,4-diaminophenyl sulfone, 24g polybutadiene rubber, 4g adhesion promoter, 2g anti-hydrolysis agent, 4g nano-sized titanium dioxide, and 2g micron-sized silica; thus, the surface anti-corrosion sealing layer fiber filament material of Example 2 is obtained.

[0022] Example 3 differs from Example 1 in that it contains a carbon fiber bicycle rim with the following raw material composition: the pretreated fiber filaments weigh 550g, and the modified adhesive weighs 450g; wherein the modified adhesive comprises 275g epoxy resin, 95g 4,4-diaminobenzene, 45g polybutadiene rubber, 10g adhesion promoter, 7.5g anti-hydrolysis agent, 12.5g nano-sized titanium dioxide, and 12.5g micron-sized silicon dioxide; thus, the surface anti-corrosion sealing layer fiber filament material for the bicycle rim of Example 3 is obtained.

[0023] Comparative Example 1 differs from Example 1 in that it contains no adhesive accelerator, anti-hydrolysis agent, or acid and alkali resistant additive; thus, the filament material for bicycle wheels of Comparative Example 1 is obtained.

[0024] The difference between Comparative Example 2 and Example 1 is that the fibers in Comparative Example 2 are treated by natural air drying. The adhesive solution for Comparative Example 2 was prepared by adding all components into a mixing device and shearing and mixing at 1600 rpm for 35 minutes at 80°C; subsequently, a single layer of adhesive was applied to 100 μm release paper; the composite parameters were 30 GPa / cm at 100°C. 2 Pressure pressing was performed at a speed controlled at 10 m / min; the material was cured at 100℃ for 2 hours to obtain the fiber material for bicycle wheels in Comparative Example 2.

[0025] The corrosion resistance of the rib fiber materials from Examples 1-3, Comparative Examples 1 and 2 was tested, including salt spray test at 35°C with 5% NaCl, immersion in 5% HCl for 72 hours, immersion in 5% NaOH for 72 hours, and damp heat aging test at 85°C / 85% RH for 60 days. The results are shown in Table 1 below. Table 1. Corrosion resistance test results of Examples 1 to 3 and Comparative Examples 1 and 2

[0026] As shown in the table above, the fiber materials for bicycle rims in Examples 1 to 3 have multiple protective effects due to the addition of anti-hydrolysis agents and acid and alkali resistant additives, as well as the application of gradient coating and fluorocarbon resin sealing. The salt spray life is 4-5 times that of the comparative examples, and the mass change after acid and alkali immersion is only 1 / 30-1 / 50 of that of the comparative examples. The filament materials for wheel rims from Examples 1 to 3, as well as Comparative Examples 1 and 2, were subjected to ultra-high temperature resistance tests, including tensile strength retention tests at 200°C and wheel rim deformation tests at 180°C for 2 hours. The results are shown in Table 2 below. Table 2. Ultra-high temperature resistance test results of fiber materials for bicycle rims in Examples 1-3 and Comparative Examples 1 and 2.

[0027] As shown in the table above, the filament materials for wheel rims in Examples 1 to 3 retain more than 80% of their tensile strength at 200℃; and the deformation of the wheel rims after being kept at 180℃ for 2 hours is much smaller than that of the comparative examples.

[0028] The rim filament materials from Examples 1 to 3, as well as Comparative Examples 1 and 2, were respectively manufactured into complete rims using the following processes: Winding: The fiber material is spirally wound on the wheel mold, with eight layers in total, symmetrical between the inner and outer layers; Hot pressing curing: Place the wound mold into a hot press and press at 130°C for 2 hours at a pressure of 3MPa; Machining: After hot pressing and demolding, CNC machine the inner and outer diameters of the wheel rim and valve holes, and grind the surface; Coating: Apply protective paint by spraying.

[0029] Wheel performance tests were conducted on the rims of Examples 1 to 3, as well as Comparative Examples 1 and 2. The mechanical performance test results are shown in Table 3 below. Table 3. Test results of the mechanical properties of the wheel rims in Examples 1-3 and Comparative Examples 1 and 2.

[0030] As shown in Table 3 above, the radial / lateral stiffness of the wheel rims of Examples 1 to 3 is 15%-30% higher than that of Comparative Examples 1 and 2, and the fatigue life is extended by 2-3 times. The rims of Examples 1 to 3, as well as Comparative Examples 1 and 2, were subjected to 1000km of real-world road testing. The results are shown in Table 4 below. Table 4 shows the results of real-world road condition tests conducted on the rims of Examples 1-3, Comparative Examples 1 and 2 over a distance of 1000km.

[0031] As shown in Table 4 above, the wheel rims of Examples 1 to 3 of this application showed no obvious damage after 1000km; the wheel rims of Comparative Examples 1 and 2 showed severe deformation and cracks, and the rolling resistance increased dramatically.

[0032] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any other way. Any person skilled in the art may make changes or modifications to the above-disclosed technical content to create equivalent embodiments that can be applied to other fields. However, any simple modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the protection scope of the present invention.

Claims

1. A carbon fiber bicycle rim, characterized in that, The product includes rib filaments, the raw material composition of which, by weight, is as follows: 50-80 parts of pretreated rib filaments and 20-50 parts of modified adhesive; wherein, the pretreated rib filaments include carbon fibers. The modified adhesive has the following raw material composition by weight: 80-120 parts epoxy resin, 30-40 parts 4,4-diaminophenyl sulfone curing agent, 10-20 parts polybutadiene rubber toughening agent, 2-4 parts adhesion promoter, 1-3 parts anti-hydrolysis agent, 2-5 parts acid and alkali resistant additive, and 1-5 parts micron-sized silica.

2. The carbon fiber bicycle rim according to claim 1, characterized in that, The bonding promoter is γ-aminopropyltriethoxysilane; the anti-hydrolysis agent is carbodiimide; and the acid and alkali resistant additive is nano-titanium dioxide with a particle size controlled at 1-3 μm.

3. A carbon fiber bicycle rim according to claim 1, characterized in that, The epoxy value of the epoxy resin is controlled at 0.86-0.91 eq. / 100g.

4. A method for preparing carbon fiber filament material for bicycle rims according to any one of claims 1-3, characterized in that, The process includes the following steps: fiber surface activation treatment, stepwise preparation of modified adhesive, gradient coating and pre-curing, high-pressure lamination and step curing, and surface anti-corrosion sealing.

5. The method for preparing carbon fiber filament material for bicycle rims according to claim 4, characterized in that, The specific steps for the surface activation treatment of the fibers are as follows: Degreasing: Place the fiber in 75% ethanol and ultrasonically clean for 20 minutes to remove surface oil. Plasma etching: The degreased fibers are fed into a low-pressure radio frequency plasma treatment system and treated for 5-8 minutes with oxygen as the gas source at a power of 300-500W. Coupling agent impregnation: The plasma-etched fiber filaments were immersed in a 1% γ-aminopropyltriethoxysilane ethanol solution and soaked at 30°C for 30 min; then dried at 80°C for 1 h to obtain the pretreated fiber filaments; the volume ratio of γ-aminopropyltriethoxysilane to anhydrous ethanol in the 1% γ-aminopropyltriethoxysilane ethanol solution was 1:

10.

6. The method for preparing a carbon fiber filament material for bicycle rims according to claim 4, characterized in that, The specific steps for preparing the modified adhesive solution are as follows: Epoxy resin premixing: Take epoxy resin, add anti-hydrolysis agent, and put it into a high-speed mixer and stir for 15 minutes at 60℃ and 1000rpm; to obtain phase A; Additive dispersion: The dried 4,4-diaminophenyl sulfone curing agent and polybutadiene rubber toughening agent were poured into another high-speed mixer and stirred at 500 rpm at 70°C to preheat and mix the curing agent and toughening agent. Then, while maintaining the temperature, the speed was increased to 800 rpm and nano-titanium dioxide was added, and stirring continued for 10 minutes. Finally, while maintaining the temperature, the speed was increased to 1200 rpm and micron-sized silica was added, and stirring continued for 15 minutes to obtain phase B. Composite mixing: Add the above phase A and phase B to the bonding accelerator and feed them into another high-speed mixer equipped with shearing and grinding. Shear and grind at 75℃ and 1600rpm for 25-40min to obtain the modified adhesive.

7. The method for preparing carbon fiber filament material for bicycle rims according to claim 4, characterized in that, The specific steps for gradient adhesive application and pre-curing are as follows: Undercoat application: Apply the modified adhesive at a ratio of 20-190 g / m² 2 Coated onto 80-150μm release paper, pre-baked at 45℃ for 8 minutes to form a preliminary adhesive layer on the release paper; Reinforcing layer coating: A layer of concentrated adhesive containing 5% nano titanium dioxide is coated on the bottom adhesive and pre-baked at 50°C for 5 minutes to obtain two layers of gradient coated release paper.

8. The method for preparing carbon fiber filament material for bicycle rims according to claim 7, characterized in that, The specific steps of high-pressure composite and stepped curing are as follows: Composite: Two layers of gradient-coated release paper are symmetrically placed between two pressure rollers, and then pre-treated fiber filaments are laid flat between the two layers of gradient-coated release paper; subsequently, the mixture is subjected to a pressure of 35 GPa / cm at 110℃. 2 Pressure is applied for compounding at a speed of 3-15 m / min to obtain a fiber-adhesive composite preform. Step curing: The fiber-adhesive composite preform is fed into a step curing oven and cured at 120°C for 1.5 hours, then heated to 150°C for 1 hour; finally cooled to 90°C and held for 1 hour to obtain the fiber material for bicycle wheels.

9. A method for preparing carbon fiber filament material for bicycle rims according to claim 8, characterized in that, The specific steps for applying the surface anti-corrosion sealing layer are as follows: Cleaning: Rinse the surface of the composite material with deionized water, and then dry it in an oven at 60°C; Coating and sealing: Spray a fluorocarbon resin coating onto the surface of the cleaned and dried rim fiber material, and then place it in a curing oven at 120°C for 40 minutes to achieve a surface anti-corrosion sealing layer for the fiber material.

10. A method for preparing carbon fiber filament material for bicycle rims according to claim 9, characterized in that, The fluorocarbon resin coating has a thickness of 10-15 μm.

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