High-toughness modified mc nylon composite material and its application in centrifugal casting integrated elevator wheel

Abstract

The application discloses a high-strength and high-toughness modified MC nylon composite material and application thereof in a centrifugal casting integrated elevator wheel. The composite material is prepared by anion polymerization of caprolactam, stepwise addition of toluene diisocyanate, first nanoparticles with surface grafted short-chain poly-caprolactam, and pre-prepared TDI bridged graphene oxide-aminosilicone hybrid second nanoparticles. In the centrifugal casting elevator wheel, the outer peripheral surface of the metal bushing is bonded with a silane coupling agent layer, and the terminal amino groups are covalently connected with the MC nylon molecular chain through a urea bond formed by the reaction of TDI added in the second step. The application utilizes the stepwise introduction of TDI and the difference in reaction kinetics to simultaneously achieve quasi-uniform dispersion of functional fillers in a centrifugal field, chemical bonding of the metal-nylon interface, and construction of a heat-conducting network-self-lubricating micro-reservoir in the rope groove area in a single process. The application systematically solves the problems of uneven radial performance, interface loosening, and accelerated wear of the rope groove due to thermal softening of the existing centrifugal casting integrated elevator wheel, and significantly improves the comprehensive service life.

Description

Technical Field

[0001] This invention relates to the field of polymer composite materials technology, and more specifically, to a high-strength and tough modified MC nylon composite material and its application in centrifugally cast integrated elevator wheels. Background Technology

[0002] Due to its excellent mechanical strength, wear resistance, and self-lubricating properties, MC nylon has been widely used in the manufacture of key transmission components such as elevator traction sheaves and guide wheels. To further enhance its overall performance, nanofillers or lubricating components are typically introduced into the caprolactam polymerization system to achieve effects such as reinforcement and friction reduction.

[0003] The applicant's prior patent (publication number CN121182194A) proposes a low-friction coefficient nylon modified material, which constructs a hybrid particle by chemically bridging graphene oxide and amino-terminated polysiloxane using toluene diisocyanate (TDI). This approach covalently bonds the "hard" reinforcing phase and the "soft" lubricating phase at the molecular level, thus breaking the traditional rule that "reduced friction inevitably leads to reduced strength" in modification processes.

[0004] However, when this type of general-purpose modified material was applied to the specific product and process of "centrifugally cast integrated elevator wheel", the inventors discovered three levels of technical defects that the prior art had failed to foresee and resolve.

[0005] First, there is the problem of disordered filler behavior under centrifugal force. Centrifugal casting processes generate radial centrifugal forces tens of times stronger than gravity. Under this dynamic and continuous force, reinforcing particles with a density greater than that of caprolactam melt migrate rapidly to the outer ring before polymerization and solidification, resulting in significant unevenness in the radial performance of the wheel body. Existing dispersion methods based on static casting cannot effectively counteract this centrifugal driving force. It is worth noting that some existing technologies even actively utilize this effect to prepare gradient materials, but this runs counter to the fundamental pursuit of "overall structural uniformity" in this field, directly leading to increased brittleness in the outer ring rope groove region due to filler oversaturation and insufficient strength in the inner ring near-bulb region due to filler depletion.

[0006] Secondly, there is the issue of interface reliability. Centrifugally cast integrated elevator wheels typically integrate a steel bushing with an MC nylon wheel body, and their fit relies heavily on the physical interlocking formed by machining annular grooves on the bushing. The coefficients of thermal expansion of MC nylon and steel differ by nearly an order of magnitude. Under the long-term exposure to thermal cycles and frequent start-stop operations within the elevator shaft, cumulative thermal stress will accumulate at the interface. This "micro-creep-micro-slippage" effect will gradually wear down the nylon embedded in the groove, leading to a loose fit.

[0007] Finally, there is the problem of frictional heat accumulation in the rope groove. MC nylon has extremely low intrinsic thermal conductivity, making it difficult for the frictional heat generated by the elevator traction sheave rope groove during heavy-load, high-speed operation to dissipate quickly. When the local temperature of the rope groove becomes too high, the material undergoes significant thermal softening, leading to an exponential increase in the wear rate. This positive feedback loop of "frictional heat generation - thermal softening - more severe wear" has not been systematically blocked in traditional lubrication modification schemes.

[0008] The three problems mentioned above do not exist in isolation during the service life of centrifugally cast integrated elevator wheels, but rather exacerbate each other. Therefore, a systematic technical solution is urgently needed to address these interconnected problems in an integrated manner, from the centrifugal molding stage to the service operation stage. Summary of the Invention

[0009] The present invention aims to provide a high-strength and tough modified MC nylon composite material and its application in centrifugally cast integrated elevator wheels, so as to systematically solve the problems faced by the existing technology under centrifugal casting conditions, such as poor controllability of filler dispersion, insufficient service reliability of metal-nylon interface, and accelerated wear caused by frictional heat of rope groove.

[0010] The core concept of this invention is to use toluene diisocyanate (TDI) as a unified chemical node throughout the entire material and molding system. Through three carefully designed microstructures and precise control of the timing of TDI introduction and reaction path, the quasi-uniform dispersion of reinforcing fillers, covalent bonding at the metal-polymer interface, and the synergistic effect of thermal conductivity and lubrication in the rope groove region can be achieved simultaneously in a single process.

[0011] This invention first provides a high-strength and tough modified MC nylon composite material, which is mainly made from the following raw materials by weight through anionic polymerization: 100 parts caprolactam; 0.15-2.5 parts anionic polymerization catalyst; 1.0-6 parts toluene diisocyanate (TDI), wherein the toluene diisocyanate is introduced into the reaction system in a stepwise manner; 0.5-5 parts of first nanoparticles, wherein the surface of the first nanoparticles is grafted with short chains of polycaprolactam (PA6) with a molecular weight of 800-4000; and 0.8-4 parts of second nanoparticles, wherein the second nanoparticles are pre-generated covalently bonded hybrid particles formed by bridging graphene oxide and amino-terminated polysiloxane with toluene diisocyanate introduced in the first step.

[0012] The first nanoparticle forms the basis of the "dispersion regulation" of this invention. The PA6 short chains grafted on its surface fully extend and swell in the caprolactam melt, greatly increasing the hydrodynamic volume of the particles and causing their effective density to converge towards the melt. Under the action of a centrifugal force field, the radial migration rate of these polymer brush-like particles is significantly slowed down, thereby achieving a relatively uniform distribution within the wheel body before polymerization and solidification on a macroscopic scale.

[0013] The second nanoparticle forms the basis of the "lubrication-reinforcement integration" of this invention. It chemically bridges the graphene oxide with the terminal amino polysiloxane through pre-added TDI, ensuring that the lubrication segments do not exist in a free state. During the subsequent centrifugal casting process, thanks to the inherent low surface energy of the polysiloxane segments, these hybrid particles exhibit a tendency to slowly migrate and accumulate on the free surface of the wheel body, particularly in the rope groove region. This results in a nanoscale-thick, chemically bonded polysiloxane-rich layer naturally forming on the surface of the elevator wheel's rope grooves after molding, serving as a long-lasting solid self-lubricating micro-reservoir.

[0014] In some embodiments, the first nanoparticle preferably comprises boron nitride nanosheets (BNNS). It is important to note that due to the chemical inertness of the BNNS surface, it is difficult to directly graft PA6 short chains; therefore, the present invention requires a surface activation pretreatment. Specifically, the BNNS is first dispersed in a dopamine-containing buffer solution, and a polydopamine (PDA) active layer rich in hydroxyl and amino groups is coated onto the BNNS surface using the self-polymerization reaction of dopamine under weakly alkaline conditions. This PDA layer acts as a "molecular glue" and reaction platform, efficiently initiating the anionic ring-opening polymerization of caprolactam on its surface, thereby achieving high-density grafting of PA6 short chains. After this step, the grafting density of BNNS can reach a level comparable to that of graphene oxide.

[0015] After successfully grafting PA6 short chains, the grafted BNNS can not only achieve stable suspension in a centrifugal force field, but its ultra-high in-plane thermal conductivity can also construct efficient phonon transport channels in the matrix. When the volume fraction of BNNS reaches or exceeds its percolation threshold, it can form a through-type thermally conductive network in the MC nylon matrix, efficiently guiding the frictional heat at the rope groove to the inside of the wheel body and the metal bushing, fundamentally weakening the underlying driving force of "thermal softening" that accelerates wear.

[0016] In some embodiments, to further optimize the balance between thermal conductivity and mechanical properties, the first nanoparticle can be a combination of boron nitride nanosheets and graphene oxide. Graphene oxide can provide additional reinforcement and help adjust the melt viscosity of the composite material system.

[0017] In some embodiments, to achieve the optimal synergistic effect of lubrication and enhancement, the mass ratio of graphene oxide to amino-terminated polysiloxane in the second nanoparticle is preferably 1:0.8 to 1:4.

[0018] Based on the aforementioned composite material, the present invention further provides a centrifugally cast integrated elevator wheel. This elevator wheel includes a metal bushing and an MC nylon wheel body centrifugally cast onto its outer periphery. Its key interfacial structural features are: a silane coupling agent layer is bonded to the outer peripheral surface of the metal bushing, exposing terminal amino groups; the MC nylon wheel body is formed from the composite material described above; and the terminal amino groups on the outer peripheral surface of the metal bushing are covalently linked to the polycaprolactam molecular chains constituting the MC nylon wheel body via urea bonds, wherein the urea bonds are formed by the reaction of the isocyanate groups of toluene diisocyanate added in the second step with the terminal amino groups.

[0019] This demonstrates the key design feature of TDI as a "unified chemical node." This scheme incorporates TDI in two steps through time-controlled addition. The first step involves pre-adding a portion of TDI during the preparation of the second nanoparticle, ensuring its specificity in bridging the GO and PDMS reactions. This step is performed in vitro and does not interfere with subsequent processes. The second step involves adding the remaining TDI as an activator to the active solution containing the first nanoparticle before centrifugation and casting. At this point, the newly added TDI molecules face two reaction opportunities simultaneously: reacting with the highly reactive terminal amino groups on the metal bushing surface, or participating in the ring-opening polymerization of caprolactam.

[0020] Because the reaction rate constant of TDI with -NH2 is much higher than its rate of initiating caprolactam polymerization, when the feed liquid comes into contact with the preheated metal bushing, TDI preferentially and rapidly reacts with the terminal amino groups on the bushing surface to form urea bond anchors. This interfacial reaction is completed in a very short time, consuming only a small portion of the TDI. Subsequently, after the induction period of the polymerization reaction, the vast majority of TDI participates as an activator in the anionic ring-opening polymerization of caprolactam, while simultaneously forming covalent bonds with the end groups of the PA6 short chains on the surface of the first nanoparticle, chemically anchoring them within the matrix network. The entire process is naturally regulated by the differences in reaction kinetics, with each function proceeding in parallel and in an orderly manner.

[0021] Thus, a highly dense monolayer "bridge" connected by covalent bonds is constructed at the microscopic interface between metal and polymer, upgrading the traditional macroscopic physical interlocking to molecular-level chemical bonding.

[0022] It is worth emphasizing that this invention, through the same TDI component and by utilizing stepwise addition and natural regulation of reaction kinetics, simultaneously achieves three functions: "pre-construction of reinforcing-lubricating hybrid particles," "preferential covalent bonding of metal-nylon interfaces," and "chemical anchoring of grafted nanoparticles to the PA6 matrix." This "one molecule, three functions" system design results in a significant synergistic effect between the components and structures, rather than conventional physical blending or functional superposition.

[0023] Furthermore, this invention effectively utilizes the slight gradient effect that cannot be completely eliminated in the centrifugal casting process. Although the first nanoparticle is grafted and modified, its effective density may still differ slightly from that of the melt, resulting in a controllable, slowly increasing distribution of its content from the inside out in the radial direction of the wheel body. This gradient precisely matches the service requirements of elevator wheels: the inner ring near the bushing region is rich in PA6 matrix, exhibiting high toughness and effectively absorbing and buffering thermal expansion stress and load impact from the metal bushing; the outer ring rope groove region is enriched with nanofillers, resulting in higher strength and stiffness, and the thermal conductivity network and lubrication film are also most concentrated, achieving optimal overall wear resistance. This invention transforms the centrifugal force field, which was the root cause of problems in the prior art, into a powerful tool for constructing ideal "functionally graded materials."

[0024] Compared with the prior art, the present invention has the following beneficial effects: This invention relates to a modified MC nylon composite material and elevator wheel. Starting from the actual molding process and service conditions of centrifugally cast integrated elevator wheels, it systematically addresses a series of related technical challenges from microscopic dispersion to macroscopic interfaces, and then to long-term thermo-coupling service. Through the stepwise introduction of TDI, a unified chemical node, and the natural regulation of reaction kinetics, this invention achieves organic unity and functional synergy across three dimensions: filler dispersion regulation, preferential chemical bonding at the metal-nylon interface, and the synergistic design of rope groove thermal conductivity and lubrication. This holistic technical solution not only effectively overcomes the problem of uneven dispersion caused by centrifugal force fields but also reconstructs the metal-polymer interface structure at the molecular level, significantly improving the structural integrity and dimensional stability of the integrated elevator wheel under harsh conditions such as alternating hot and cold temperatures and frequent start-stop under heavy loads. Simultaneously, through the synergistic effect of constructing a thermally conductive network and a surface self-lubricating micro-reservoir, it breaks the vicious cycle of "thermal softening-accelerated wear" in the rope groove region from both the "heat source" and "heat conduction" directions, fundamentally improving the wear resistance life of the elevator wheel. Detailed Implementation

[0025] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0026] In this instruction manual, some English abbreviations have the following meanings: “MC Nylon” refers to Monomer Casting Nylon. “GO” refers to graphene oxide. “TDI” refers to toluene diisocyanate. “BNNS” refers to boron nitride nano-sheets. "PA6" refers to polycaprolactam, also known as nylon 6; “PDMS” refers to polysiloxane, namely polydimethylsiloxane; "KH-550" refers to γ-aminopropyltriethoxysilane; "PDA" refers to polydopamine.

[0027] I. Raw material preparation and precursor preparation Before preparing the composite materials and elevator wheels of the examples and comparative examples, two types of nano-modified particles need to be prepared in advance: first nanoparticles (functional nanoparticles with surface-grafted PA6 short chains) and second nanoparticles (GO-PDMS hybrid particles).

[0028] The preparation method of the first nanoparticle is as follows: (A) For nanofillers with oxygen-containing functional groups on their surface, such as graphene oxide (GO) or nano-silica (SiO2): Dry nanofillers are directly dispersed in anhydrous toluene and sonicated for 30 min to form a uniform suspension. The required amount of caprolactam and a small amount of alkaline catalyst (such as sodium caprolactam) are added to the suspension. The mixture is heated to 120–140 °C under nitrogen protection and stirred for 2–6 h. Caprolactam undergoes anionic ring-opening polymerization at the hydroxyl or carboxyl initiation sites on the nanoparticle surface, generating surface-grafted PA6 short chains. After the reaction, the nanoparticles are obtained by centrifugation, washing, and vacuum drying.

[0029] (B) For surface-inert nanofillers such as boron nitride nanosheets (BNNS): Surface activation pretreatment is necessary first. BNNS is dispersed in a dopamine Tris-HCl buffer solution with a pH of 8.5 and a concentration of 2 g / L, and stirred at room temperature for 12–24 h. During this process, dopamine undergoes oxidative self-polymerization under weakly alkaline conditions, forming a polydopamine (PDA) active coating layer with a thickness of approximately 5–20 nm on the BNNS surface. After washing and drying, BNNS@PDA particles are obtained. The surface of these particles is rich in active groups such as phenolic hydroxyl and amino groups. Subsequently, using the particles as an initiation platform, caprolactam anionic ring-opening polymerization can be carried out according to the method described in (A) above to obtain high-graft-density BNNS-PA6 first nanoparticles.

[0030] By adjusting the feed ratio of caprolactam to nanoparticles and the reaction time, the molecular weight and grafting density of the grafted PA6 short chains can be controlled. The molecular weight of the grafted PA6 short chains ranges from 800 to 4000, and the grafting density is 0.1 to 0.5 chains / nm. 2 .

[0031] The preparation method of the second nanoparticle is as follows: Graphene oxide (GO) was dispersed in anhydrous N,N-dimethylformamide and ultrasonically exfoliated for 1 h to obtain a GO dispersion. A terminal amino polysiloxane was dissolved in an appropriate amount of solvent, and the first batch of TDI was added dropwise under nitrogen protection and stirring. The reaction was carried out at 60–80 °C for 1–3 h, allowing one isocyanate group of TDI to preferentially react with the terminal amino group of the terminal amino polysiloxane. Then, the GO dispersion was added, and the temperature was raised to 80–100 °C for another 2–4 h, allowing the other isocyanate group of TDI to react with the oxygen-containing groups on the GO surface, thus forming a hybrid structure where GO and PDMS are covalently bridged by TDI. After the reaction, the particles were washed and vacuum dried to obtain the pre-generated second nanoparticles. The mass ratio of GO to terminal amino polysiloxane was 1:0.8–1:4. At this point, the first batch of TDI had been completely consumed.

[0032] II. General Manufacturing Method for Centrifugally Cast Integrated Elevator Wheels Step 1: Surface pretreatment of metal bushings A ring-shaped metal bushing made of No. 45 steel is used, with annular grooves pre-machined on its outer circumference for physical fitting. The outer circumference of the metal bushing is degreased and roughened by sandblasting, then ultrasonically cleaned with anhydrous ethanol and dried. The metal bushing is immersed in an ethanol-water solution of 1%–3% by mass of γ-aminopropyltriethoxysilane (KH-550) for 30–60 min at room temperature. After removal, the free silane coupling agent on the surface is rinsed with anhydrous ethanol, and then dried and cured at 100–120°C for 30 min, thus forming a self-assembled layer of silane coupling agent with terminal amino groups bonded on the outer circumference of the metal bushing.

[0033] Step 2: Preparation of active caprolactam melt By weight, 100 parts of caprolactam are heated to 100–120°C to completely melt them. Then, 0.15–2.5 parts of anionic polymerization catalyst (preferably sodium hydroxide or sodium caprolactam) are added, stirred evenly, and dehydrated under vacuum until the water content of the system is reduced to below 300 ppm. Subsequently, the melt temperature is adjusted to 130–140°C.

[0034] Step 3: Introduction of functional fillers A predetermined number of first and second nanoparticles are dispersed in a small amount of dry caprolactam melt under ultrasonic assistance to form a concentrated suspension. The suspension is then added to the active caprolactam melt obtained in step two. Under the combined action of mechanical stirring and ultrasound, the nanoparticles are fully dispersed to form a uniform active liquid.

[0035] Step 4: Centrifugal casting and the second step of TDI introduction After preheating the metal bushing from step one to 150–170°C, place it into a centrifugal casting mold. Add the second batch of TDI (i.e., the remaining portion of the TDI by weight as described in the claims and invention) as an activator to the active liquid obtained in step three, stir rapidly until homogeneous, and then pour it into the centrifugal mold containing the metal bushing. Start the centrifuge and carry out the centrifugal polymerization reaction at a mold speed of 800–2000 r / min and a mold temperature of 150–170°C. After holding the reaction at this temperature for 20–40 minutes, stop heating and allow the mold to cool naturally to below 80°C under centrifugal conditions. Demolding yields the centrifugally cast integrated elevator wheel.

[0036] During this molding process, the introduction of the second batch of TDI triggered the following ordered cascade reaction: 1. Preferential bonding at the interface: When the liquid feed comes into contact with the preheated metal bushing, the newly added TDI molecules preferentially react rapidly with the highly reactive terminal amino groups on the bushing surface to form urea bonds, anchoring one end of the TDI to the metal surface. This step consumes a small amount of TDI.

[0037] 2. Polymerization and Network Construction: Subsequently, most of the TDI reacts with caprolactam molecules under the action of an alkaline catalyst, initiating anionic ring-opening polymerization to generate MC nylon molecular chains. During this process, another isocyanate group of TDI anchored to the metal surface also participates in the polymerization, incorporating into the growing PA6 chain, thereby achieving covalent bonding between the metal and the polymer.

[0038] 3. In-situ particle anchoring: During the polymerization process, TDI and caprolactam react with the active end groups of the PA6 short chains grafted onto the surface of the first nanoparticle, anchoring the first nanoparticle to the MC nylon matrix network by chemical bonds. Simultaneously, the pre-generated second nanoparticle also participates in this polymerization-crosslinking network through its remaining surface active sites.

[0039] Step 5: Post-processing After demolding, the elevator wheels are placed in boiling water for 2–8 hours to remove residual monomers and oligomers, and to relieve some internal stress. Then they are slowly cooled to room temperature with water.

[0040] III. Examples and Comparative Examples Example 1 Elevator wheels were prepared using the general preparation method described above. The first nanoparticle used was BNNS grafted with PA6 after PDA activation (the short chain of grafted PA6 had a molecular weight of approximately 2000, and the grafting density was approximately 0.15 strands / nm). 2 The first batch of TDI was used in a ratio of 3 parts by weight; the second batch of TDI had a ratio of 1:1.5 for GO:PDMS and was used in a ratio of 1.5 parts by weight. The total amount of TDI used was 4.5 parts by weight, of which about 1.0 part was consumed in the first batch (for the preparation of the second nanoparticles) and about 3.5 parts were added in the second batch (for casting).

[0041] Example 2 Based on Example 1, the molecular weight of the PA6 short chains grafted onto the surface of the first nanoparticle was adjusted to approximately 800, and the grafting density was correspondingly adjusted to approximately 0.4 chains / nm. 2 .

[0042] Example 3 Based on Example 1, the molecular weight of the PA6 short chains grafted onto the surface of the first nanoparticle was adjusted to approximately 4000, and the grafting density was approximately 0.1 chains / nm. 2 .

[0043] Example 4 Based on Example 1, the first nanoparticles were adjusted to be a combination of BNNS and GO, with a mass ratio of 1.5:1 (approximately 1.8 parts of BNNS and approximately 1.2 parts of GO), and the total amount used remained 3 parts by weight.

[0044] Comparative Example 1 Three parts of unmodified raw BNNS were introduced as filler, and the rest was the same as in Example 1.

[0045] Comparative Example 2 The metal bushing is not pretreated with silane coupling agent, and only the pure physical interlocking structure of the annular groove is retained, otherwise it is the same as in Example 1.

[0046] Comparative Example 3 The first nanoparticles were all replaced with PA6-grafted GO, and no BNNS were introduced. The rest was the same as in Example 1.

[0047] Comparative Example 4 It adopts the D1 scheme without introducing the first nanoparticles, without pre-treating the metal bushing, and is formed by general casting.

[0048] Comparative Example 5 All 4.5 parts of TDI were pre-reacted with GO and PDMS in one step to generate the second nanoparticles. No additional TDI was added during casting, and the rest was the same as in Example 1.

[0049] IV. Performance Testing and Result Analysis

[0050] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A high-strength and high-toughness modified MC nylon composite material, characterized in that, The components include the following parts by weight: Caprolactam, 100 parts; Anionic polymerization catalyst, 0.15–2.5 parts; Toluene diisocyanate, 1.0 to 6 parts, wherein the toluene diisocyanate is introduced into the reaction system in a stepwise manner; First nanoparticle, 0.5 to 5 parts, wherein the surface of the first nanoparticle is grafted with short chains of polycaprolactam with a molecular weight of 800 to 4000. The second nanoparticle, 0.8 to 4 parts, is a pre-generated covalently bonded hybrid particle formed by bridging graphene oxide and amino-terminated polysiloxane with toluene diisocyanate introduced in the first step.

2. The high-strength and high-toughness modified MC nylon composite material according to claim 1, characterized in that, The first nanoparticle is selected from at least one of boron nitride nanosheets grafted with short polycaprolactam chains, graphene oxide, and nano-silica; wherein the surface of the boron nitride nanosheets is pre-coated with a polydopamine active layer to promote the grafting of short polycaprolactam chains.

3. The high-strength and high-toughness modified MC nylon composite material according to claim 1 or 2, characterized in that, The grafting density of the polycaprolactam short chains on the surface of the first nanoparticle is 0.1–0.5 chains / nm. 2 .

4. The high-strength and high-toughness modified MC nylon composite material according to claim 1, characterized in that, In the second nanoparticle, the mass ratio of graphene oxide to amino-terminated polysiloxane is 1:0.8 to 1:

4.

5. A centrifugally cast integrated elevator wheel, comprising a metal bushing and an MC nylon wheel body centrifugally cast onto its outer periphery, characterized in that: The outer peripheral surface of the metal bushing is bonded with a silane coupling agent layer, the silane coupling agent layer exposing terminal amino groups; The MC nylon wheel body is formed of the composite material according to any one of claims 1 to 4; The terminal amino group on the outer peripheral surface of the metal bushing is covalently linked to the polycaprolactam molecular chain constituting the MC nylon wheel body through urea bonds. The urea bonds are formed by the reaction of the isocyanate group of the toluene diisocyanate added in the second step with the terminal amino group. The main part of the toluene diisocyanate added in the second step is used to initiate the anionic ring-opening polymerization of caprolactam and anchor the first nanoparticles in the matrix.

6. The centrifugally cast integrated elevator wheel according to claim 5, characterized in that, The silane coupling agent forming the silane coupling agent layer is γ-aminopropyltriethoxysilane.

7. The centrifugally cast integrated elevator wheel according to claim 5, characterized in that, The first nanoparticle constituting the MC nylon wheel body contains boron nitride nanosheets grafted with short chains of polycaprolactam after activation with polydopamine, and the volume fraction of the boron nitride nanosheets in the MC nylon wheel body is 0.5% to 3%.

8. The centrifugally cast integrated elevator wheel according to claim 7, characterized in that, The MC nylon wheel body also contains graphene oxide as the first nanoparticle component, and the mass ratio of boron nitride nanosheets to graphene oxide is 2:1 to 1:

2.

9. The centrifugally cast integrated elevator wheel according to claim 5, characterized in that, The groove region of the MC nylon wheel is enriched with polysiloxane segments exposed from the second nanoparticles.

10. The centrifugally cast integrated elevator wheel according to claim 5, characterized in that, The MC nylon wheel body exhibits an increasing gradient distribution of the content of the first nanoparticles along its radial outward direction.

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