High-wear-resistance modified nylon-based material and preparation method thereof

Abstract

The invention relates to the technical field of polyamide materials, in particular to a high-wear-resistance modified nylon-based material and a preparation method thereof.The high-wear-resistance modified nylon-based material is prepared from, by weight, 50-70 parts of modified nylon, 5-8 parts of glass fibers, 1-3 parts of a silane coupling agent, 1-3 parts of boron nitride, 2-5 parts of silicon dioxide and 0.2-0.6 part of a heat stabilizer. Through the high-temperature shearing action of the twin-screw extrusion process, oriented arrangement of the glass fibers and uniform dispersion of the filler are realized, and interface defects are avoided. A silane coupling agent is activated in a premixing stage to reinforce a fiber-matrix interface transition layer, and a fluorinated chain segment is migrated on the surface in a melting process to form a directional lubricating layer, so that the material has good melting flowability, stable molding shrinkage and uniform performance, and the industrial production requirements are met.

Description

Technical Field

[0001] The present invention relates to the technical field of polyamide materials, and particularly relates to a highly wear-resistant modified nylon-based material and a preparation method thereof. Background Art

[0002] Since nylon (PA) was industrially applied in the mid-20th century, it has developed into one of the five major engineering plastics with the largest usage. In the field of mechanical manufacturing, nylon materials are widely used in the manufacture of key moving parts such as gears, bearings, and guide rails due to their high specific strength, self-lubricating characteristics, and good fatigue resistance. Especially with the rapid development of Industry 4.0 and intelligent manufacturing, robot technology has put forward higher requirements for the comprehensive performance of structural materials: it is necessary to withstand high-frequency dynamic loads and maintain stable tribological performance under limited lubrication conditions, which poses a new technical challenge to traditional nylon materials. In the composition of a robot system, the service environment of core components such as joint assemblies, transmission mechanisms, and load-bearing frames is particularly harsh. Taking a six-axis industrial robot as an example, its rotating joints need to complete hundreds of precision movements per minute, the transmission components are long-term subjected to large contact stresses, and at the same time, there is a relatively high relative sliding speed.

[0003] However, the tribological performance of traditional nylon matrices is not sufficient to meet the requirements of high-frequency mechanical movements. A relatively high friction coefficient not only exacerbates energy loss during movement but also easily causes local temperature rise, and the insufficient thermal stability of the material itself will lead to a phased decline in mechanical properties. On the other hand, under the continuous action of contact stress, the wear rate of the material still cannot meet the long-term service requirements of precision transmission components, and the accumulation of surface damage may cause problems such as an increase in the fit clearance and a decrease in movement accuracy, and in severe cases, it may even cause mechanism jamming or functional failure. Summary of the Invention

[0004] In order to solve the problems mentioned in the above background art, the present invention provides a highly wear-resistant modified nylon-based material and a preparation method thereof.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions: A highly wear-resistant modified nylon-based material, comprising the following raw materials in parts by weight: 50-70 parts of modified nylon, 5-8 parts of glass fiber, 1-3 parts of silane coupling agent, 1-3 parts of boron nitride, 2-5 parts of silicon dioxide, and 0.2-0.6 parts of heat stabilizer.

[0006] Further, the silane coupling agent includes one of silane coupling agent KH-550, silane coupling agent KH-792, silane coupling agent KH-560, and silane coupling agent KH-570.

[0007] Further, the heat stabilizer includes one of triphenyl phosphite, tris(nonylphenyl) phosphite, calcium stearate, and zinc stearate.

[0008] Further, the modified nylon is prepared by the following steps: S1. Caprolactam and sodium hydroxide are added into a reaction kettle. Under the protection of nitrogen, after sealing, the temperature is raised for reaction for 4 - 5 h. After the reaction ends, the reaction solution is poured into methanol while it is still hot, left standing for 1 - 2 h, the precipitate is filtered, washed 3 times with methanol, and dried at 80 °C for 12 h to obtain a nylon 6 prepolymer; S2. The nylon 6 prepolymer is added into N,N - dimethylformamide, divinylbenzene and azobisisobutyronitrile are added. Under the protection of nitrogen, the temperature is raised for reaction for 4 - 6 h. After the reaction ends, the reaction solution is poured into methanol for precipitation while it is still hot, left standing for 1 - 2 h and then filtered, washed 3 times with methanol, and dried at 80 °C for 6 h to obtain slightly cross - linked nylon 6; S3. The slightly cross - linked nylon 6 is added into hexafluoroisopropanol, perfluorobutylethylene, azobisisobutyronitrile and dodecyl mercaptan are added. Under the protection of nitrogen, the temperature is raised for reaction for 10 - 12 h. After the reaction ends, the reaction solution is cooled to room temperature, and is gradually dropped into methanol for precipitation, left standing for 10 - 12 h, filtered and washed 3 times with methanol, and dried at 60 °C for 12 h to obtain the modified nylon.

[0009] Further, in step S1, the mass ratio of caprolactam to sodium hydroxide is 100:(0.3 - 0.8), and the reaction conditions are: the temperature for raising the temperature is 240 - 250 °C, the pressure is 0.2 - 0.4 MPa, and the stirring speed is 200 - 300 rpm.

[0010] Further, in step S2, the mass ratio of the nylon 6 prepolymer, N,N - dimethylformamide, divinylbenzene and azobisisobutyronitrile is 100:(380 - 400):(11 - 13):(0.8 - 1), and the reaction conditions are: the temperature for raising the temperature is 80 - 85 °C, and the stirring speed is 100 - 200 rpm.

[0011] Further, in step S3, the mass ratio of the slightly cross - linked nylon 6, hexafluoroisopropanol, perfluorobutylethylene, azobisisobutyronitrile and dodecyl mercaptan is 100:(400 - 450):(10 - 20):(1.5 - 3):(0.1 - 0.3), and the reaction conditions are: the temperature for raising the temperature is 70 - 75 °C, and the stirring speed is 150 - 250 rpm.

[0012] According to another aspect of the present invention, there is provided a method for preparing the above - mentioned high - wear - resistant modified nylon - based material, including the following steps: Add glass fiber and heat stabilizer to a mixer according to parts by weight, heat up for pre-mixing for 5 - 10 min, add silane coupling agent, continue mixing for 10 - 20 min, add modified nylon, boron nitride and silicon dioxide, mix for 15 - 25 min until uniform, add the mixture to a twin-screw extruder, set the temperature range, melt and extrude, then water-cool and pelletize to obtain a high wear-resistant modified nylon-based material.

[0013] Furthermore, the temperature for heating up in the mixer is 80 - 85 °C, and the mixing speed in the mixer is 1000 - 2000 rpm.

[0014] Furthermore, the pelletizing temperature in the twin-screw extruder is 240 - 250 °C, and the screw rotation speed is 100 - 200 rpm.

[0015] Advantages of the present invention: 1. In the technical solution of the present invention, the "crosslinking-fluorination" synergistic structure constructed by staged chemical modification endows the material with excellent wear resistance. First, introduce a divinylbenzene covalent crosslinking network into the nylon 6 prepolymer to form a three-dimensional molecular skeleton, effectively restricting the slippage and plastic deformation of molecular chains and resisting the damage of frictional shear force. Second, the fluorinated surface layer formed by grafting perfluorobutyl ethylene significantly reduces the surface energy of the material, reduces the adhesion effect between friction pairs, and at the same time, fluorocarbon fragments form a self-lubricating transfer film at the friction interface, further reducing the friction coefficient. In addition, the layered structure of boron nitride and the synergistic mechanism of hard particles of silicon dioxide reduce the shear stress and increase the surface hardness respectively, enabling the material to maintain stable tribological properties under high-frequency dynamic loads and greatly extending the service life.

[0016] 2. In the technical solution of the present invention, the crosslinking network inhibits the high-temperature relaxation of molecular chains through the thermal binding effect of covalent bonds and delays the thermal decomposition process. The chemical inertness of the surface fluorinated layer forms a dense barrier to block the penetration of oxygen, moisture and corrosive media, reducing the hydrolysis and oxidation risks of the nylon main chain. The composite heat stabilizer synergistically blocks the thermal oxidation chain reaction through the dual mechanisms of chelating metal ions and capturing free radicals, enabling the material to maintain stable mechanical properties under high-temperature working conditions and avoiding the performance decline caused by thermal softening of traditional nylon.

[0017] 3. In the technical solution of the present invention, after the glass fiber is surface-modified by silane coupling agent, it forms a strong interfacial bond with the nylon matrix, and improves the tensile strength and impact resistance through the fiber bridging effect. The crosslinking network endows the material with rigidity, while the amorphous region induced by fluorinated side chains allows local deformation energy dissipation, avoiding brittle fracture caused by excessive crosslinking. At the same time, the hydrophobic characteristics of the crosslinking structure and the fluorinated layer synergistically inhibit the moisture absorption tendency of nylon, maintaining dimensional stability and being suitable for the long-term service of precision transmission components.

[0018] 4. In the technical solution of the present invention, the low polarity of the surface fluorination layer and the high chemical stability of the C-F bond enable the material to have remarkable tolerance to oil stains, acids, alkalis and organic solvents. The synergistic effect of the cross-linked network and the rigid filler restricts swelling deformation and reduces the medium penetration path.

[0019] 5. In the technical solution of the present invention, through the high-temperature shearing action of the twin-screw extrusion process, the oriented arrangement of glass fibers and the uniform dispersion of fillers are realized, avoiding interface defects. The activation treatment of the silane coupling agent in the premixing stage strengthens the fiber-matrix interface transition layer, and the surface migration of the fluorinated segments during the melting process forms an oriented lubricating layer, enabling the material to have good melt fluidity, a stable molding shrinkage rate and uniform performance, meeting the requirements of industrial production. Specific Embodiments

[0020] The technical solution of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0021] Unless otherwise specified, the raw materials used in the present invention are all conventional products purchased from the market.

[0022] Preparation Example 1 The modified nylon is prepared through the following steps: S1. Add 100 g of caprolactam and 0.3 g of sodium hydroxide to a reaction kettle. Under nitrogen protection, seal and heat up to 240 °C, with a pressure of 0.2 MPa, and stir and react at a speed of 200 rpm for 4 h. After the reaction is completed, pour the reaction solution into methanol while it is hot, let it stand for 1 h, filter the precipitate, wash it 3 times with methanol, and dry it at 80 °C for 12 h to obtain nylon 6 prepolymer; S2. Add 100 g of nylon 6 prepolymer to 380 g of N,N-dimethylformamide, add 11 g of divinylbenzene and 0.8 g of azobisisobutyronitrile. Under nitrogen protection, heat up to 80 °C and stir and react at a speed of 100 rpm for 4 h. After the reaction is completed, pour the reaction solution into methanol to precipitate while it is hot, let it stand for 1 h and then filter, wash it 3 times with methanol, and dry it at 80 °C for 6 h to obtain lightly cross-linked nylon 6; S3. Add 100 g of lightly cross-linked nylon 6 to 400 g of hexafluoroisopropanol, add 10 g of perfluorobutylethylene, 1.5 g of azobisisobutyronitrile and 0.1 g of dodecyl mercaptan. Under nitrogen protection, heat up to 70 °C and stir and react at a speed of 150 rpm for 10 h. After the reaction is completed, cool the reaction solution to room temperature, dropwise add it into methanol to precipitate, let it stand for 10 h, filter and wash it 3 times with methanol, and dry it at 60 °C for 12 h to obtain the modified nylon.

[0023] Preparation Example 2 The modified nylon is prepared by the following steps: S1. Add 100 g of caprolactam and 0.5 g of sodium hydroxide into a reaction kettle. Under the protection of nitrogen, seal it and heat it up to 245 °C with a pressure of 0.3 MPa. Stir and react at a speed of 250 rpm for 4 - 5 h. After the reaction is completed, pour the reaction solution into methanol while it is hot, let it stand for 1.5 h, filter the precipitate, wash it with methanol three times, and dry it at 80 °C for 12 h to obtain a nylon 6 prepolymer; S2. Add 100 g of the nylon 6 prepolymer into 391 g of N,N - dimethylformamide, add 12.3 g of divinylbenzene and 0.9 g of azobisisobutyronitrile. Under the protection of nitrogen, heat it up to 82 °C and stir and react at a speed of 150 rpm for 5 h. After the reaction is completed, pour the reaction solution into methanol while it is hot to precipitate, let it stand for 1.5 h and then filter, wash it with methanol three times, and dry it at 80 °C for 6 h to obtain slightly cross - linked nylon 6; S3. Add 100 g of the slightly cross - linked nylon 6 into 437 g of hexafluoroisopropanol, add 13 g of perfluorobutylethylene, 2.2 g of azobisisobutyronitrile and 0.2 g of dodecyl mercaptan. Under the protection of nitrogen, heat it up to 72 °C and stir and react at a speed of 200 rpm for 11 h. After the reaction is completed, cool the reaction solution to room temperature and dropwise add it into methanol to precipitate. Let it stand for 11 h, filter and wash it with methanol three times, and dry it at 60 °C for 12 h to obtain the modified nylon.

[0024] Preparation Example 3 The modified nylon is prepared by the following steps: S1. Add 100 g of caprolactam and 0.8 g of sodium hydroxide into a reaction kettle. Under the protection of nitrogen, seal it and heat it up to 250 °C with a pressure of 0.4 MPa. Stir and react at a speed of 300 rpm for 5 h. After the reaction is completed, pour the reaction solution into methanol while it is hot, let it stand for 2 h, filter the precipitate, wash it with methanol three times, and dry it at 80 °C for 12 h to obtain a nylon 6 prepolymer; S2. Add 100 g of the nylon 6 prepolymer into 400 g of N,N - dimethylformamide, add 13 g of divinylbenzene and 1 g of azobisisobutyronitrile. Under the protection of nitrogen, heat it up to 85 °C and stir and react at a speed of 200 rpm for 6 h. After the reaction is completed, pour the reaction solution into methanol while it is hot to precipitate, let it stand for 2 h and then filter, wash it with methanol three times, and dry it at 80 °C for 6 h to obtain slightly cross - linked nylon 6; S3. Add 100 g of lightly cross-linked nylon 6 to 450 g of hexafluoroisopropanol, add 20 g of perfluorobutylethylene, 3 g of azobisisobutyronitrile, and 0.3 g of dodecyl mercaptan. Under nitrogen protection, heat up to 75 °C and stir and react at a speed of 250 rpm for 12 h. After the reaction is completed, cool the reaction solution to room temperature, dropwise add it into methanol for precipitation, let it stand for 12 h, filter, wash it with methanol three times, and dry it at 60 °C for 12 h to obtain modified nylon.

[0025] Example 1 A preparation method of a highly wear-resistant modified nylon-based material, comprising the following steps: Add 5 parts by weight of glass fiber and 0.2 part of triphenyl phosphite to a mixer, heat up to 80 °C, premix at a speed of 1000 rpm for 5 min, add 1 part of silane coupling agent KH-550, continue to mix at a speed of 1000 - 2000 rpm for 10 min, add 50 parts of the modified nylon prepared in Preparation Example 1, 1 part of boron nitride, and 2 parts of silicon dioxide, mix at a speed of 1000 rpm for 15 min until uniform, add the mixture to a twin-screw extruder, the granulation temperature is 240 °C, the screw speed is 100 rpm, melt extrude and then water-cool and pelletize to obtain a highly wear-resistant modified nylon-based material.

[0026] Example 2 A preparation method of a highly wear-resistant modified nylon-based material, comprising the following steps: Add 6 parts by weight of glass fiber and 0.4 part of tris(nonylphenyl) phosphite to a mixer, heat up to 82 °C, premix at a speed of 1500 rpm for 8 min, add 2 parts of silane coupling agent KH-792, continue to mix at a speed of 1500 rpm for 15 min, add 61 parts of the modified nylon prepared in Preparation Example 2, 2 parts of boron nitride, and 3 parts of silicon dioxide, mix at a speed of 1500 rpm for 20 min until uniform, add the mixture to a twin-screw extruder, the granulation temperature is 245 °C, the screw speed is 150 rpm, melt extrude and then water-cool and pelletize to obtain a highly wear-resistant modified nylon-based material.

[0027] Example 3 A preparation method of a highly wear-resistant modified nylon-based material, comprising the following steps: Add 8 parts by weight of glass fiber and 0.6 part of calcium stearate to a mixer, heat up to 85 °C, premix at a speed of 2000 rpm for 10 min, add 3 parts of silane coupling agent KH-570, continue to mix at a speed of 2000 rpm for 20 min, add 70 parts of the modified nylon prepared in Preparation Example 3, 3 parts of boron nitride, and 2 - 5 parts of silicon dioxide, mix at a speed of 2000 rpm for 25 min until uniform, add the mixture to a twin-screw extruder, the granulation temperature is 250 °C, the screw speed is 200 rpm, melt extrude and then water-cool and pelletize to obtain a highly wear-resistant modified nylon-based material.

[0028] Comparative Example 1 The difference between this comparative example and Preparation Example 1 is that divinylbenzene is not added in Step S2, and the remaining steps are the same as those in Preparation Example 1, obtaining a nylon material.

[0029] Comparative Example 2 The difference between this comparative example and Preparation Example 2 is that perfluorobutylethylene is not added in Step S3, and the remaining steps are the same as those in Preparation Example 2, obtaining a nylon material.

[0030] Comparative Example 3 The difference between this comparative example and Example 1 is that the nylon material prepared in Comparative Example 1 is used to replace the modified nylon prepared in Preparation Example 1, and the remaining steps are the same as those in Example 1.

[0031] Comparative Example 4 The difference between this comparative example and Example 2 is that the nylon material prepared in Comparative Example 2 is used to replace the modified nylon prepared in Preparation Example 2, and the remaining steps are the same as those in Example 2.

[0032] Comparative Example 5 The difference between this comparative example and Example 3 is that commercially available nylon 6 is used to replace the modified nylon prepared in Preparation Example 3, and the remaining steps are the same as those in Example 3.

[0033] Referring to ASTM G99 "Test Method for Wear Testing with a Pin-on-Disk Apparatus", the nylon-based materials of Examples 1 - 3 and Comparative Examples 3 - 5 were injection molded into standard block specimens with dimensions of 30 mm × 7 mm × 6 mm and a contact surface of a 30 mm × 7 mm plane. The surface of the specimens was polished with 2000-mesh sandpaper. All specimens were placed in a drying oven at 50 °C for 24 h for standby before testing. The GCr15 steel ring was fixed on the main shaft of the testing machine, and the specimens were vertically installed in the fixture to ensure that the contact surface was parallel to the axis of the steel ring. The testing machine was started, loaded to 200 N, pre-run for 5 min at a rotational speed of 200 rpm to eliminate surface asperities, and then continuously run for 2 h for formal testing. The torque (T, unit: N·m) was recorded, and the test was repeated 3 times. After the test, the load was unloaded and the specimens were removed. The friction coefficient (μ) was calculated as μ = T / (F·r), where T is the torque, F is the load, and r is the radius of the steel ring, 20 mm. The results are shown in Table 1: Table 1. Test Results of Friction and Wear Properties of Examples 1 - 3 and Comparative Examples 3 - 5

[0034] The nylon-based materials of Examples 1 - 3 and Comparative Examples 3 - 5 were cut into type I dumbbell-shaped specimens with dimensions of 57 mm × 13 mm × 3 mm and a total length of 165 mm. The surface of the specimens was polished with 2000-mesh sandpaper to obtain tensile specimens.

[0035] The nylon-based materials of Examples 1-3 and Comparative Examples 3-5 were processed into rectangular specimens with dimensions of 63.5 mm × 12.7 mm × 3.2 mm. A notch was made in the middle of the specimen, with a notch depth of 2.5 mm and a root radius of 0.25 mm, to obtain notched impact specimens.

[0036] All specimens were placed in a thermostatic and humidistatic chamber at a temperature of 23 ± 2 °C and a humidity of 50 ± 5% for 48 h. Before testing, the surface of the specimens was wiped with anhydrous ethanol to remove dust and grease.

[0037] (I) Tensile property test: The specimen was vertically installed in the fixture of a universal material testing machine, ensuring that the gauge section was aligned with the tensile axis. The tensile rate was set at 50 mm / min. After the specimen broke, the test was immediately stopped, and the gauge section length (L 断裂 ), and the maximum load (F max ) were recorded. This was repeated 3 times, and the tensile strength (σ) and elongation at break (ε) were calculated. The calculation formulas are as follows:

[0038]

[0039] where A0 is the initial cross-sectional area and L0 is the initial gauge length.

[0040] (II) Notched impact strength test: A pendulum impact testing machine (range 0 - 25 J, accuracy ±1%) was used to calibrate the pendulum energy and impact velocity (3.5 m / s). The support span of the specimen was adjusted to 40 mm, ensuring that the notch faced away from the impact direction. The notched specimen was horizontally placed on the support table, with the notch center aligned with the pendulum blade edge. The pendulum was released to impact the specimen, and the impact energy (E) was recorded. This was repeated 3 times. The notched impact strength (a k ) was calculated. The calculation formula is as follows:

[0041] where b is the specimen width and d is the specimen thickness.

[0042] The results of the tensile property test and the notched impact strength test are shown in Table 2: Table 2. Mechanical property test results of Examples 1-3 and Comparative Examples 3-5

[0043] As can be seen from Table 1, the friction coefficients of Examples 1-3 are significantly lower than those of Comparative Examples 3-5. The friction coefficients of Examples 1-3 are between 0.09 and 0.11, while the friction coefficients of Comparative Examples 3-5 are between 0.18 and 0.36. The torques of Examples 1-3 are also significantly lower than those of Comparative Examples 3-5. The torques of Examples 1-3 are between 0.36 and 0.43 N·m, and the torques of Comparative Examples 3-5 are between 0.70 and 1.42 N·m. The results show that the high wear-resistant modified nylon-based materials prepared in Examples 1-3 have better wear resistance.

[0044] As can be seen from Table 2, the tensile strength, elongation at break and notched impact strength of Examples 1-3 are all better than those of Comparative Examples 3-5. The tensile strength of Examples 1-3 is between 97 and 106 MPa, while the tensile strength of Comparative Examples 3-5 is between 53 and 76 MPa. The elongation at break of Examples 1-3 is between 13.0 and 15.5%, and the elongation at break of Comparative Examples 3-5 is between 19.5 and 32.0%. Although the elongation at break value of the comparative examples seems relatively high, in combination with practical applications, the material needs to have sufficient strength while ensuring a certain toughness, and the tensile strength of the comparative examples is low, so the overall mechanical properties are not good. The notched impact strength of Examples 1-3 is between 10.8 and 13.4 kJ / m², and the notched impact strength of Comparative Examples 3-5 is between 4.8 and 8.2 kJ / m². It shows that the materials of Examples 1-3 have better mechanical properties.

[0045] In Step S2 of Preparation Examples 1-3, divinylbenzene was added to form a lightly cross-linked structure of nylon 6, which restricted the movement of nylon molecular chains, enhanced the intermolecular force, reduced the slip and shedding of molecular chains during the friction process, thereby reducing the friction coefficient and torque and improving the wear resistance. In Comparative Example 1, divinylbenzene was not added in Step S2, and nylon 6 did not form a cross-linked structure. The molecular chains moved relatively freely and were prone to slip and shedding during the friction process, which might lead to an increase in the friction coefficient and torque and a decrease in the wear resistance. When the nylon material prepared in Comparative Example 1 was used to replace Comparative Example 3 prepared from the modified nylon prepared in Preparation Example 1, its friction and wear performance became significantly worse.

[0046] In Step S3 of Preparation Examples 1-3, perfluorobutylethylene was added to introduce fluorine-containing groups onto the nylon molecular chains. The fluorine-containing groups have a low surface energy and can form an interfacial layer with a low friction coefficient on the material surface, reducing the adhesion to the counter-material and lowering the friction coefficient. At the same time, the fluorine-containing groups can also improve the hydrophobicity and chemical stability of the material, reducing the wear caused by the erosion of moisture and chemical substances to the material. In Comparative Example 2, perfluorobutylethylene was not added in Step S3, and no interfacial layer with a low friction coefficient was formed on the surface of the nylon material, so the friction coefficient was relatively high. When the nylon material prepared in Comparative Example 2 was used to replace Comparative Example 4 prepared from the modified nylon prepared in Preparation Example 2, its friction and wear performance also decreased.

[0047] The lightly cross-linked structure enhances the interaction between nylon molecular chains, allowing the material to better transfer stress when subjected to stress, thereby improving the tensile strength and notched impact strength of the material. Since no cross-linked structure is formed in Comparative Example 1, the interaction between molecular chains is weak, and slippage and breakage are prone to occur when subjected to stress, resulting in low tensile strength and notched impact strength. Comparative Example 3, in which the nylon material prepared in Comparative Example 1 is used to replace the modified nylon prepared in Preparation Example 1, has significantly worse mechanical properties.

[0048] The introduction of fluorine-containing groups improves the interfacial properties of the material to a certain extent, making the bonding between fillers such as glass fiber, boron nitride and silicon dioxide and the nylon matrix more closely, and improving the overall mechanical properties of the material. Since no fluorine-containing groups are introduced in Comparative Example 2, the bonding between the filler and the nylon matrix is relatively weak, and the mechanical properties of the material are affected. Comparative Example 4, in which the nylon material prepared in Comparative Example 2 is used to replace the modified nylon prepared in Preparation Example 2, also has a decreased mechanical property. Comparative Example 5 uses commercially available nylon 6, which has not been modified, and its molecular chain structure and properties are quite different from those of modified nylon, resulting in the worst mechanical properties.

[0049] In summary, by introducing a lightly cross-linked structure and fluorine-containing groups during the preparation of nylon, the prepared modified nylon significantly improved the friction and wear properties and mechanical properties of the highly wear-resistant modified nylon-based material.

[0050] In the description of the specification, the description with reference to the terms "preparation example", "embodiment", "various embodiments" and the like means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or preparation example are included in at least one embodiment or preparation example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or preparation example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or preparation examples in a suitable manner.

[0051] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A highly wear-resistant modified nylon-based material, characterized in that, It comprises the following raw materials by weight parts: 50-70 parts of modified nylon, 5-8 parts of glass fiber, 1-3 parts of silane coupling agent, 1-3 parts of boron nitride, 2-5 parts of silicon dioxide, and 0.2-0.6 part of heat stabilizer.

2. The high wear-resistant modified nylon-based material according to claim 1, wherein The silane coupling agent includes one of silane coupling agent KH-550, silane coupling agent KH-792, silane coupling agent KH-560, and silane coupling agent KH-570.

3. A highly wear-resistant modified nylon-based material according to claim 1, characterized in that The heat stabilizer includes one of triphenyl phosphite, tris(nonylphenyl) phosphite, calcium stearate, and zinc stearate.

4. A highly wear-resistant modified nylon-based material according to claim 1, characterized in that, The modified nylon is prepared by the following steps: S1. Add caprolactam and sodium hydroxide into a reaction kettle. Under nitrogen protection, seal and heat up for reaction for 4-5 h. After the reaction ends, pour the reaction solution into methanol while it is hot, let it stand for 1-2 h, filter the precipitate, wash, and dry to obtain nylon 6 prepolymer. S2. Add the nylon 6 prepolymer into N,N-dimethylformamide, add divinylbenzene and azobisisobutyronitrile. Under nitrogen protection, heat up for reaction for 4-6 h. After the reaction ends, pour the reaction solution into methanol to precipitate while it is hot, let it stand for 1-2 h and then filter, wash, and dry to obtain slightly crosslinked nylon 6. S3. Add the slightly crosslinked nylon 6 into hexafluoroisopropanol, add perfluorobutylethylene, azobisisobutyronitrile, and dodecyl mercaptan. Under nitrogen protection, heat up for reaction for 10-12 h. After the reaction ends, cool the reaction solution to room temperature, dropwise add it into methanol to precipitate, let it stand for 10-12 h, filter and then wash and dry to obtain modified nylon.

5. A highly wear-resistant modified nylon-based material according to claim 4, characterized in that, In step S1, the mass ratio of caprolactam to sodium hydroxide is 100:(0.3-0.8), and the reaction conditions are: the temperature for heating up is 240-250 °C, the pressure is 0.2-0.4 MPa, and the stirring speed is 200-300 rpm.

6. A highly wear-resistant modified nylon-based material according to claim 4, characterized in that, In step S2, the mass ratio of nylon 6 prepolymer, N,N-dimethylformamide, divinylbenzene, and azobisisobutyronitrile is 100:(380-400):(11-13):(0.8-1), and the reaction conditions are: the temperature for heating up is 80-85 °C, and the stirring speed is 100-200 rpm.

7. A highly wear-resistant modified nylon-based material according to claim 4, characterized in that, In step S3, the mass ratio of slightly crosslinked nylon 6, hexafluoroisopropanol, perfluorobutylethylene, azobisisobutyronitrile, and dodecyl mercaptan is 100:(400-450):(10-20):(1.5-3):(0.1-0.3), and the reaction conditions are: the temperature for heating up is 70-75 °C, and the stirring speed is 150-250 rpm.

8. A method for preparing a highly wear-resistant modified nylon-based material according to any one of claims 1-7, characterized in that, It includes the following steps: Add glass fiber and heat stabilizer into a mixer by weight parts, heat up and premix for 5-10 min, add the silane coupling agent, continue mixing for 10-20 min, add the modified nylon, boron nitride, and silicon dioxide, mix for 15-25 min until uniform, add the mixture into a twin-screw extruder, melt and extrude, and then water-cool and pelletize to obtain a high wear-resistant modified nylon-based material.

9. The preparation method of the highly wear-resistant modified nylon-based material according to claim 8, characterized in that, The temperature for heating up in the mixer is 80-85 °C, and the mixing speed in the mixer is 1000-2000 rpm.

10. The preparation method of the highly wear-resistant modified nylon-based material according to claim 8, characterized in that, The pelletizing temperature in the twin-screw extruder is 240-250 °C, and the screw rotation speed is 100-200 rpm.

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