High-strength ferrite plastic magnetic granule and preparation method thereof

Abstract

The invention relates to the technical field of preparation methods of high-strength ferrite plastic magnetic granules, in particular to high-strength ferrite plastic magnetic granules and a preparation method thereof.The high-strength ferrite plastic magnetic granules are prepared from, by weight, 84 wt%-90 wt% of ferrite magnetic powder, 8 wt%-13 wt% of binder, 1 wt%-3 wt% of flexibilizer, 0.3 wt%-0.8 wt% of coupling agent and 0.5 wt%-1.5 wt% of lubricant. 0.2 wt% to 0.5 wt% of an antioxidant; the ferrite magnetic powder is strontium ferrite or barium ferrite or combined magnetic powder of the strontium ferrite and the barium ferrite, and the average particle size is 0.8-2.0 microns; the binder is composed of nylon 6 powder modified by a fiber material, and the fiber material is selected from one of long glass fiber and carbon fiber. Tests prove that the ferrite injection molding granules provided by the invention have the maximum magnetic energy product (BH) max of more than or equal to 15.1 kJ / m < 3 >, the bending strength of not less than 150MPa and the crushing strength of more than or equal to 60MPa, have good magnetic properties and relatively high mechanical properties, and are suitable for extrusion of complex shapes.

Description

Technical Field

[0001] This invention relates to the technical field of high-strength ferrite plastic magnetic granules preparation methods, and particularly to a high-strength ferrite plastic magnetic granule and its preparation method. Background Technology

[0002] Injection-molded magnets are functional materials prepared through a polymer composite process. The production process mainly involves three key steps: first, magnetic powder raw materials are mixed with polymer binders and processing aids in a specific ratio and then granulated; subsequently, the resulting composite particles are injection molded under precise temperature control using injection molding equipment. Magnets produced by this process have significant industrialization advantages, with core characteristics including: 1. Precision molding capability of three-dimensional structures; 2. Excellent mechanical strength and durability; 3. Feasibility for continuous industrial production. Based on these technological advantages, injection-molded magnets have achieved important applications in several high-tech fields: in the information technology field, they are mainly used in computer storage devices, mobile communication devices, and smart terminal components; in the precision electromechanical field, they are widely used in micro-special motors, sensor arrays, and high-precision measuring instruments; in the consumer electronics field, they are mainly used in digital imaging equipment, smart wearable devices, and automated office systems. Furthermore, this material also shows broad application prospects in emerging fields such as new energy vehicle drive systems and smart home control modules.

[0003] Currently, improving the mechanical properties of injection-molded ferrites mainly involves increasing the binder content. However, this also leads to a reduction in the amount of magnetic powder, resulting in a decrease in the magnetic properties of the product. Modern industrial applications of bonded ferrite materials primarily utilize two polymer bonding systems: Nylon 6 and Nylon 12. From an engineering and economic perspective, Nylon 6 has become the mainstream choice due to its cost advantage and superior melt flow characteristics. However, its inherent drawbacks include insufficient molecular chain rigidity leading to mechanical strength deficiencies, and significant hygroscopic phenomena caused by hydrophilic groups in its molecular structure. This not only causes a double decrease in remanence and coercivity of the magnet but also directly affects the reliability of the device. In contrast, Nylon 12 exhibits superior structural stability: its increased molecular chain crystallinity reduces water absorption by approximately 40%, effectively extending the lifespan of the magnet in humid and hot environments. However, the application of this material is limited by two technical bottlenecks: First, the higher material density leads to a relatively lower proportion of functional fillers (ferrite) in the same mass formulation, which directly affects the magnetic flux density index; Second, the melt flow index is 25%-30% lower than that of Nylon 6, which puts higher requirements on the molding process of thin-walled complex structure products.

[0004] Chinese Patent Application No. 201110285377.2 discloses a ferrite injection molding granule and its preparation method. The application discloses its raw material formula, which includes the following components: 85-92 wt% ferrite magnetic powder, 0.3-0.5 wt% coupling agent, 7-14 wt% binder, and 0.1-0.5 wt% lubricant, wherein the binder is a mixture of PPS and PA. The invention also provides a method for preparing the aforementioned ferrite injection molding granules, including several steps such as magnetic powder surface modification, adhesive-magnetic mixing, lubrication, and compounding and granulation. The lubrication step is a separate step, meaning that the lubricant is added after the adhesive mixing process is completed and the magnetic powder has formed a uniform mixture with the binder. This invention enables the prepared ferrite granules to combine the characteristics of ferrite / PPS granules and ferrite / PA granules, exhibiting both good high-temperature resistance and good mechanical properties. However, its preparation cost is high, the preparation process is complex, and the strength of the ferrite granules still needs to be improved.

[0005] Chinese Patent Application No. 201611016058.0 discloses a high-performance injection-molded ferrite granule and its preparation method. The application outlines its raw material formulation, comprising: 85wt%-90wt% ferrite magnetic powder, 8wt%-13wt% binder, 0.4wt%-0.6wt% coupling agent, 0.8wt%-1.0wt% lubricant, and 0.2wt%-0.4wt% antioxidant. This invention simplifies the process, improves product flowability, and yields products with high magnetic properties, good mechanical properties, and high dimensional accuracy. However, it does not solve the key problem of poor strength in current injection-molded ferrite granule products.

[0006] Traditional ferrite-based magnetic materials use ferrite powders (such as strontium ferrite and barium ferrite) as the magnetic matrix, which are then encapsulated with thermoplastic resins (such as nylon and polypropylene). However, existing technologies suffer from the following problems: 1. Insufficient mechanical properties: When the magnetic powder filling content is too high (>90%), the material becomes brittle, and the tensile strength (<60MPa) and flexural strength (<90MPa) are insufficient to meet the requirements of high-speed rotors; 2. Poor processing performance: Improper lubricant selection leads to unstable melt flow rate (MFR), making it prone to cracks or pores during molding; 3. Imbalance between magnetic and mechanical properties: High magnetic energy product (>3.5MGOe) requires a high magnetic powder content, but a reduction in the resin binder ratio significantly weakens the mechanical properties. Therefore, a high-strength ferrite-based magnetic granule material and its preparation method are needed to solve the above problems. Summary of the Invention

[0007] The purpose of this invention is to solve the problems mentioned in the background section.

[0008] To achieve the above objectives, the present invention adopts the following technical solution:

[0009] A high-strength ferrite magnetic granule and its preparation method are disclosed. The formulation includes the following components and weight percentages: ferrite magnetic powder 84wt%-90wt%, binder 8wt%-13wt%, toughening agent 1%-3%, coupling agent 0.3wt%-0.8wt%, lubricant 0.5wt%-1.5wt%, and antioxidant 0.2wt%-0.5wt%.

[0010] Preferably, the ferrite magnetic powder is strontium ferrite or barium ferrite, or a combination of the two, with an average particle size of 0.8 μm-2.0 μm. This particle size range is highly matched with the single-domain critical size (about 1 μm) of the ferrite material. When the particle size is smaller than the single-domain size, each particle is a stable magnetic domain, and magnetization reversal is achieved only through magnetic moment rotation, thus exhibiting extremely high coercivity.

[0011] Preferably, the binder is composed of nylon 6 powder modified with fiber materials, wherein the fiber materials are selected from long glass fibers and carbon fibers, and the fiber materials are added at 12wt%-23wt% of the nylon mass ratio. Although pure nylon 6 has good toughness as a binder, its rigidity, strength, and wear resistance are limited. Adding long glass fibers or carbon fibers in this proportion is equivalent to constructing a robust three-dimensional network skeleton within the binder system.

[0012] Preferably, the toughening agent is a composite toughening agent, a maleic anhydride-grafted POE or EPDM and nano-CaCO3 composite. The maleic anhydride-grafted POE / EPDM, as the soft phase, mainly absorbs a large amount of impact energy when subjected to impact by its own large deformation, initiating crazes and shear bands, thereby significantly improving the impact strength and elongation at break of the material, i.e., providing toughness. The nano-CaCO3, as the hard phase, not only plays a certain role in rigidity enhancement and cost reduction, but more importantly, it can induce crazes, deflect crack paths, and produce a synergistic effect with the elastomer.

[0013] Preferably, the coupling agent can be one or more of silane coupling agents, titanate coupling agents, phosphate coupling agents, aluminate coupling agents, and silane-titanium ester composite systems. Different ferrite magnetic powders (strontium / barium) have different surface chemical microenvironments, and different binder and toughening agent systems (such as nylon 6, POE, etc.) also have different polarities. Providing a variety of coupling agent options allows formulation engineers to make precise matches according to the specific material system.

[0014] Preferably, the lubricant is one or more of the following: TAF (a modified product of N,N'-bis(ethylene)-stearate), PETS (pentaerythritol stearate), oxidized polyethylene wax, or silane coupling agent (KH-550) and POE elastomer complex. Different lubricants have different mechanisms of action, and this formulation provides a precise choice to achieve the best balance. TAF and PETS are excellent internal lubricants. They have good compatibility with nylon 6, can insert between macromolecular chains, reduce internal friction between molecular chains, and significantly reduce melt viscosity.

[0015] Preferably, the antioxidant is a hindered phenol + phosphite composite antioxidant or a nano-SiO2 supported antioxidant. The use of a hindered phenol + phosphite composite system is a classic strategy for the anti-oxidation of polymer materials, achieving multiple protections. This composite system provides protection throughout the entire oxidation process, and its synergistic effect is far superior to that of a single antioxidant. It can extremely effectively prevent the thermo-oxidative degradation of polymer matrices such as nylon 6 during high-temperature mixing, granulation, and subsequent injection molding, and maintain the stability of the polymer molecular weight.

[0016] A method for preparing high-strength ferrite magnetic granules includes the following steps:

[0017] The first step is surface modification: the coupling agent of the formula is sprayed evenly onto the surface of the magnetic powder in the form of a spray and then mixed and stirred at high speed to obtain the surface-treated ferrite magnetic powder.

[0018] The second step is the mixing of adhesive and magnet: the surface-treated magnetic powder is mixed evenly with the binder, lubricant and antioxidant in a high-speed mixer, and the temperature of the mixer is controlled at 80℃-120℃.

[0019] The third step is to mix and extrude the mixture in a twin-screw extruder: add the mixture obtained in step (2) into a twin-screw extruder for mixing, extrusion and granulation. The temperature of the twin-screw extruder is controlled at 235℃-265℃. After the mixed material is extruded, it is granulated to obtain the final product.

[0020] This invention has at least the following beneficial effects:

[0021] 1. The ferrite injection-molded granules provided by this invention, after testing, have a maximum magnetic energy product (BH)max ≥ 15.1 kJ / m. 3 It has a flexural strength of not less than 150MPa and a crushing strength of ≥60MPa. It has good magnetic properties and high mechanical properties, and is suitable for extrusion of complex shapes.

[0022] 2. By employing magnetic powder (0.8–2.0 μm) that matches the single-domain size and maintaining an extremely high magnetic powder filling rate (84–90 wt%), the material is ensured to possess high coercivity and high magnetic energy product ((BH)max ≥ 15.1 kJ / m²). 3This innovative material uses fiber-reinforced nylon 6 as a binder and introduces a composite toughening system, achieving excellent flexural strength (≥150MPa) and crushing strength (≥60MPa) even in a high-fill state. This granular material combines the cost advantage of nylon 6 with performance comparable to high-end materials. Its excellent flowability and high mechanical strength make it very suitable for manufacturing magnetic components with complex shapes, thin walls, and stringent requirements for strength and magnetism.

[0023] 3. It provides a variety of optimized selection options for coupling agents, lubricants and antioxidants, enabling precise control of the interfacial compatibility, melt flowability and thermo-oxidative stability of each component. This design effectively reduces the melt viscosity of the high-filler system, avoids agglomeration and degradation during processing, ensures smooth mixing, granulation and injection molding, and at the same time enables the final product to have good dimensional stability and long-term durability. Attached Figure Description

[0024] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the following description of the embodiments will be briefly introduced. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0025] Figure 1 This is a schematic diagram of a method for preparing high-strength ferrite magnetic granules proposed in this invention. Detailed Implementation

[0026] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0027] Example 1:

[0028] Reference Figure 1 A high-strength ferrite magnetic granule material and its preparation method are disclosed. The formula includes the following components and weight percentages: 87.6 wt% strontium ferrite magnetic powder, 9.4 wt% nylon binder, 1.2% POE and nano-CaCO3 composite toughening agent, 0.6 wt% silane coupling agent Si-900 coupling agent, 0.8 wt% PETS (pentaerythritol stearate) lubricant, and 0.2% antioxidant 1010 + 0.2% antioxidant 168. In this embodiment, long glass fiber modified nylon 6 is added at a mass ratio of 18%, that is, the mass ratio of long glass fiber is 18%, while the mass ratio of nylon 6 is 82%.

[0029] Ferrite magnetic powder is strontium ferrite or barium ferrite, or a combination of the two, with an average particle size of 0.8μm-2.0μm.

[0030] The binder is composed of nylon 6 powder modified with fiber material, which is selected from long glass fiber and carbon fiber, and is added at 12wt%-23wt% of the nylon mass ratio.

[0031] The toughening agent is a composite toughening agent, which is a composite of maleic anhydride grafted with POE or EPDM and nano-CaCO3.

[0032] The coupling agent can be one or more of the following: silane coupling agent, titanate coupling agent, phosphate coupling agent, aluminate coupling agent, and silane-titanium ester composite system.

[0033] The lubricant is one or more of the following: TAF (a modified product of N,N'-bisethylene stearamide), PETS (pentaerythritol stearate), oxidized polyethylene wax, or silane coupling agent (KH-550) combined with POE elastomer.

[0034] The antioxidant is a hindered phenol + phosphite composite antioxidant or a nano-SiO2 supported antioxidant.

[0035] A method for preparing high-strength ferrite magnetic granules is as follows:

[0036] 1. Surface modification of strontium ferrite magnetic powder: First, a 0.6 wt% silane coupling agent Si-900 solution is sprayed onto the strontium ferrite magnetic powder by high-pressure spraying and mixed evenly. Then, it is dried at a temperature of 80-115℃ to obtain modified strontium ferrite magnetic powder, wherein the strontium ferrite magnetic powder is 1.3 μm in size.

[0037] 2. Modification of the binder: Modified nylon 6 was obtained by blending 18 wt% of long glass fibers and 82 wt% of nylon 6, which constitute the binder.

[0038] 3. Mixing process: 87.6 wt% of modified strontium ferrite magnetic powder, 9.4 wt% of modified nylon 6, 1.2 wt% of POE and nano-CaCO3 composite toughening agent, 0.6 wt% of silane coupling agent Si-900 coupling agent, 0.8 wt% of PETS (pentaerythritol stearate) lubricant, 0.2% of antioxidant 1010 and 0.2% of antioxidant 168 are added to a high-speed mixer and mixed evenly to obtain a mixture of magnetic powder and binder;

[0039] 4. Mixing, granulation and extrusion process: The mixture is fed into a twin-screw extruder for mixing, extrusion and pelletizing to finally obtain strontium ferrite injection molded granules;

[0040] 5. Place the granules into an injection molding machine and inject them into the required standard test samples under a 1T magnetic field. The magnet samples obtained in this embodiment were tested and found to have a magnetic energy product (BH) of 15.8 kJ / m, a flexural strength of 163.7 MPa, a tensile strength of 88 MPa, and a compressive strength of 73 MPa.

[0041] Example 2:

[0042] A high-strength ferrite-based magnetic granule material and its preparation method are disclosed. The formulation includes the following components and weight percentages: 88.1 wt% of a 2:1 mixture of strontium ferrite magnetic powder and barium ferrite magnetic powder; 8.7 wt% of nylon binder; 1.4 wt% of an EPDM and nano-CaCO3 composite toughening agent; 0.6 wt% of KH-550 silane coupling agent; 0.8 wt% of TAF lubricant; and 0.3 wt% of nano-SiO2 antioxidant. In this embodiment, carbon fiber is added at a mass ratio of 15% in the carbon fiber-modified nylon 6, meaning that the carbon fiber accounts for 15% of the mass ratio, while the nylon 6 accounts for 85% of the mass ratio.

[0043] Ferrite magnetic powder is strontium ferrite or barium ferrite, or a combination of the two, with an average particle size of 0.8μm-2.0μm.

[0044] The binder is composed of nylon 6 powder modified with fiber material, which is selected from long glass fiber and carbon fiber, and is added at 12wt%-23wt% of the nylon mass ratio.

[0045] The toughening agent is a composite toughening agent, which is a composite of maleic anhydride grafted with POE or EPDM and nano-CaCO3.

[0046] The coupling agent can be one or more of the following: silane coupling agent, titanate coupling agent, phosphate coupling agent, aluminate coupling agent, and silane-titanium ester composite system.

[0047] The lubricant is one or more of the following: TAF (a modified product of N,N'-bisethylene stearamide), PETS (pentaerythritol stearate), oxidized polyethylene wax, or silane coupling agent (KH-550) combined with POE elastomer.

[0048] The antioxidant is a hindered phenol + phosphite composite antioxidant or a nano-SiO2 supported antioxidant.

[0049] A method for preparing high-strength ferrite magnetic granules is as follows:

[0050] 1. Ferrite powder mixing: First, add strontium ferrite powder and barium ferrite powder to a high-speed mixer at a weight ratio of 2:1 and mix for 5-8 minutes. The particle size of both strontium ferrite powder and barium ferrite powder is 1.5μm.

[0051] 2. Modification of ferrite magnetic powder: First, KH-550 silane coupling agent with an addition amount of 0.6wt% is dissolved in pure water, and then added to strontium ferrite magnetic powder by high pressure spraying and mixed evenly. The powder is then dried at a temperature of 80-115℃ to obtain modified ferrite magnetic powder.

[0052] 3. Modification of the binder: Modified nylon 6 was obtained by blending 15 wt% carbon fiber and 85 wt% nylon 6, which constitute the binder.

[0053] 4. Mixing process: 88.1 wt% of modified ferrite magnetic powder, 8.7 wt% of modified nylon 6, 1.4 wt% of EPDM and nano-CaCO3 composite toughening agent, 0.8 wt% of TAF lubricant, and 0.3 wt% of nano-SiO2 antioxidant are added to a high-speed mixer and mixed evenly to obtain a mixture of magnetic powder and binder.

[0054] 5. Mixing, granulation and extrusion process: The mixture is fed into a twin-screw extruder for mixing, extrusion and pelletizing to finally obtain strontium ferrite injection molded granules;

[0055] 6. Place the granules into an injection molding machine and inject them into the required standard test samples under a 1T magnetic field. The magnet samples obtained in this embodiment are tested and the magnetic energy product (BH) reaches 15.9kJ / m, the flexural strength reaches 172.5MPa, the tensile strength reaches 91MPa, and the compressive strength reaches 81MPa.

[0056] The average particle size of ferrite magnetic powder ranges from 0.8 μm to 2.0 μm. This particle size range closely matches the critical size of a single domain in ferrite materials (approximately 1 μm). When the particle size is smaller than the single domain size, each particle constitutes a stable magnetic domain, and magnetization reversal is achieved solely through magnetic moment rotation. Therefore, it possesses extremely high coercivity. This results in the fabricated plastic magnetic particles themselves exhibiting high intrinsic coercivity, providing strong anti-demagnetization capabilities for the final injection-molded or calendered magnets. Consequently, a higher magnetic energy product (BH)max is achieved, resulting in high strength and high performance of the magnets. The smaller particle size of the magnetic powder also contributes to its high specific surface area. Large particle size makes them prone to agglomeration. When mixed and granulated with polymers (such as nylon, PP, PE, etc.), they significantly increase melt viscosity, leading to processing difficulties and limited magnetic powder filling rate. However, the particle size of 0.8μm-2.0μm effectively balances the specific surface area, resulting in better particle dispersion and good wettability with resin. This gives the granules excellent flowability in the molten state, which not only facilitates subsequent injection molding or extrusion molding but also enables higher magnetic powder volume filling rate (usually over 60%). A high filling rate is a direct guarantee for obtaining high remanent magnetization (Br) and strong magnetism.

[0057] While pure nylon 6 offers good toughness as a binder, its rigidity, strength, and wear resistance are limited. Adding long glass fibers or carbon fibers in this proportion creates a robust three-dimensional network skeleton within the binder system. The extremely high ferrite magnetic powder filling rate (typically >60wt%) leads to a sharp increase in the viscosity of the molten mixture and poor flowability, making mixing, granulation, and subsequent injection molding difficult. Fiber-modified nylon 6 matrix exhibits higher melt strength and better viscosity characteristics, maintaining good processing flowability even under high filling conditions. This allows for more uniform and smoother melting and blending of the magnetic powder and binder in a twin-screw extruder, avoiding excessive equipment load or uneven mixing due to excessive torque. This ensures a smooth preparation process and the production of high-quality granules.

[0058] Maleic anhydride-grafted POE / EPDM, as the soft phase, primarily absorbs a large amount of impact energy upon impact by inducing crazes and shear bands through its large deformation, thereby significantly improving the material's impact strength and elongation at break, thus providing toughness. Nano-CaCO3, as the hard phase, not only plays a role in enhancing rigidity and reducing costs, but more importantly, it can induce crazes, deflect crack paths, and produce a synergistic effect with the elastomer. Due to its huge specific surface area and interfacial effect, nano-scale CaCO3 can better disperse stress and work together with the elastomer to achieve a better toughening effect. Ultimately, while the impact strength of the material is greatly improved, the modulus and strength do not decrease significantly, avoiding the drawback of the material being too "soft" due to the use of elastomer alone.

[0059] Different ferrite magnetic powders (strontium / barium) have different surface chemical microenvironments, and different binder and toughening agent systems (such as nylon 6, POE, etc.) also have different polarities. A variety of coupling agents are available to allow formulation engineers to make precise matches according to the specific material system. Among them, silane coupling agents are very suitable for treating fillers with siliceous surfaces and have good compatibility with polar plastics such as nylon. Titanate / aluminate coupling agents are particularly suitable for inorganic fillers such as calcium carbonate, barium sulfate and ferrites, which can effectively treat highly filled systems and also have the effect of reducing system viscosity and promoting dispersion.

[0060] Different lubricants have different mechanisms of action. This formulation provides precise selection to achieve the best balance. TAF and PETS are excellent internal lubricants with good compatibility with Nylon 6. They can insert into the macromolecular chains, reducing internal friction between molecular chains and significantly reducing melt viscosity. The silane coupling agent (KH-550) combined with POE elastomer transcends the single function of traditional lubricants. POE elastomer itself has certain lubricity. The amine group (-NH2) of KH-550 reacts with the end group of Nylon 6, while the other end binds to POE. This allows POE to be more firmly and uniformly dispersed in the matrix. Therefore, this combination not only provides lubrication but also simultaneously achieves excellent dispersion and interfacial bonding of the toughening agent (POE), providing multiple benefits in one formulation. It solves the problems of lubrication, toughening, and interfacial compatibility at the same time. By reducing melt viscosity, the lubricant provides a better flow environment for the uniform dispersion of magnetic powder particles in the matrix, reducing agglomeration and uneven dispersion caused by excessive viscosity.

[0061] The use of a hindered phenol + phosphite composite system is a classic strategy for antioxidant protection of polymer materials, achieving multiple layers of protection. This composite system provides protection throughout the entire oxidation process, with a synergistic effect far superior to that of a single antioxidant. It can extremely effectively prevent the thermo-oxidative degradation of polymer matrices such as nylon 6 during high-temperature mixing, granulation, and subsequent injection molding, maintaining the stability of polymer molecular weight. The high-efficiency antioxidant ensures the molecular structural integrity of nylon 6 binders and toughening agents by preventing degradation, thereby maintaining the high and stable mechanical strength and magnetic properties of the product for a long time. Loading antioxidant molecules onto nano-SiO2 can slow down the migration and volatilization rate of antioxidants in the matrix, preventing them from being consumed too quickly due to high processing temperatures or long-term use, thus achieving more durable antioxidant protection and extending product life.

[0062] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the claimed invention. The scope of protection claimed by the appended claims and their equivalents is defined.

Claims

1. A high-strength ferrite plastic-magnetic granular material and a method for preparing the same, characterized by comprising the steps of: The formula includes the following components and weight percentages: ferrite magnetic powder 84wt%-90wt%, binder 8wt%-13wt%, toughening agent 1%-3%, coupling agent 0.3wt%-0.8wt%, lubricant 0.5wt%-1.5wt%, antioxidant 0.2wt%-0.5wt%. ​ 2. The high-strength ferrite plastic magnetic granules and the method for preparing the same according to claim 1, characterized in that, The ferrite magnetic powder is strontium ferrite or barium ferrite and a combination of the two, with an average particle size of 0.8-2.0 μm.

3. The high-strength ferrite-based magnetic granules and their preparation method according to claim 1, characterized in that, The binder is composed of nylon 6 powder modified by a fibrous material selected from one of long glass fiber, carbon fiber, with the fibrous material added at 12wt%-23wt% of the mass of the nylon.

4. The high-strength ferrite magnetic granules and their preparation method according to claim 1, characterized in that, The toughening agent is a composite toughening body, a maleic anhydride grafted POE or EPDM composite with nano-CaCO3.

5. The high-strength ferrite-based magnetic granules and their preparation method according to claim 1, characterized in that, The coupling agent can be one or more of a silane coupling agent, a titanate coupling agent, a phosphite coupling agent, an aluminate coupling agent, and a silane-titanate composite system.

6. The high-strength ferrite-plastic magnetic granules and their preparation method according to claim 1, characterized in that, The lubricant is one or more of TAF (a modified product of N, N'-bis ethylene stearic acid amide), PETS (pentaerythritol stearate), oxidized polyethylene wax, or a combination of silane coupling agent (KH-550) and POE elastomer.

7. The high-strength ferrite-plastic magnetic granule material and its preparation method according to claim 1, characterized in that, The antioxidant is a hindered phenol + phosphite composite antioxidant or a nano-SiO2 loaded antioxidant.

8. The method of claim 1-7, wherein the method is characterized by: The method includes the following steps: First step, surface modification: uniformly spray the coupling agent in the amount of the formula onto the surface of the magnetic powder in the form of a spray, and perform high-speed mixing and stirring to obtain the ferrite magnetic powder that has been surface treated; Second step, glue-magnetic mixing: mix the above surface treated magnetic powder with the binder, lubricant, and antioxidant uniformly in a high-speed intensive mixer, with the temperature of the mixer controlled at 80-120°C; Third step, mixing and extruding in a twin-screw extruder: add the mixture obtained in step (2) into a twin-screw extruder for mixing and extruding and granulating, with the temperature of the twin-screw extruder controlled at 235-265°C, and after the mixed material is extruded, it is cut into granules, and the process is complete.

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