Motor rotor magnetic adhesive for improving high-temperature magnetic flux, and motor rotor

Abstract

The present invention relates to the field of motor adhesives, and in particular relates to a motor rotor magnetic adhesive for improving high-temperature magnetic flux, and a motor rotor. The motor rotor magnetic adhesive comprises the following raw materials, in parts by mass: 5-15 parts of an epoxy resin, 1-3 parts of a phenolic resin, 0.5-2 parts of a curing accelerator, 15-30 parts of fused spherical silica, 40-60 parts of fused angular silica, 4-10 parts of fumed silica, 1-3 parts of a silane coupling agent, and 5-30 parts of magnetic powder, wherein the D50 of the fused spherical silica is 5-9 μm, the D50 of the fused angular silica is 15-21 μm, and the specific surface area of the fumed silica is 230-280 m2 / g. In the present invention, magnetic material powder is used as a part of a solid filler, in combination with a silica filler having a specific size, which powder improves the high-temperature magnetic flux of the overall material and also maintains good mechanical strength.

Description

A magnetic adhesive for improving high-temperature magnetic flux in motor rotors and the motor rotor itself. Technical Field

[0001] This invention relates to the field of motor adhesives, and in particular to a magnetic adhesive for motor rotors that improves high-temperature magnetic flux and a motor rotor. Background Technology

[0002] Driven by the global trend towards green energy, the gradual maturation of the new energy vehicle industry chain has provided the market with more superior options. For most new energy vehicles, the fixing method of permanent magnet motors, magnets, and iron cores is a key process. Several common methods include adhesive fixing, injection molding fixing, and riveting fixing. Adhesive fixing was an early method, using epoxy resin to fix the magnets to the rotor iron core. However, the fixing performance is unstable, and the strength decreases significantly over time. This method is basically obsolete and may only be used for small-batch prototyping experiments. Injection molding fixing is a new technology developed in recent years. It involves injecting injection molding material around the magnets to form a fixation, providing more stable performance. Mainstream materials used for magnetic fixing of motor rotors on the market include Sumitomo's M500A and Yuanzong 8200TM. With the rise of new energy vehicles and the improvement of electric vehicle performance, the demand for torque provided by the motor is increasing, especially when the motor speed exceeds 17,000 rpm. Thermosetting materials have become the preferred magnet fixing materials. Using epoxy resin to fix motor rotors is a common method. Thermosetting epoxy resins have good toughness, impact resistance, vibration resistance, and corrosion resistance, and also have excellent bonding effects, thus having a wide range of applications. However, the epoxy resin filling process can cause magnetic flux loss in the rotor, which limits its use in some scenarios. Currently, there is no fixing method that can improve the rotor's magnetic flux. Theoretically, directionally adding high-permeability magnetic powder to epoxy molding compound (EMC) may enhance the continuity of the magnetic circuit, thereby increasing the overall magnetic flux density. However, experiments have shown that directly adding magnetic powder has little effect on improving magnetic flux. There are many possible reasons for this, such as the interfacial bonding strength and dispersion uniformity between the magnetic powder and epoxy resin directly affecting the stability of magnetic permeability; it may also be due to the flowability and close packing method of non-magnetic fillers, which can all affect magnetic flux.

[0003] CN103081301B discloses a rotor comprising a rotor core fixedly disposed on a rotating shaft and having a plurality of holes arranged along the periphery of the rotating shaft; a magnet inserted into the holes; and a fixing member formed by curing a fixing resin composition that fills the separation portion between the holes and the magnet, and being disposed on at least one sidewall of the magnet located on the inner periphery of the rotor core to fix the magnet; the fixing resin composition comprises: a thermosetting resin (A) containing epoxy resin, a curing agent (B), and an inorganic filler (C); the content of the inorganic filler (C) is 50% by mass or more relative to 100% of the total value of the fixing resin composition, and the concentration of ionic impurities is 500 ppm or less relative to the fixing resin composition, wherein the ionic impurities are selected from at least one of alkali metal ions, alkaline earth metal ions, and halide ions. CN104136532A discloses a resin composition for rotor fixing, comprising a thermosetting resin containing epoxy resin, a curing agent, and an inorganic filler; the epoxy resin includes at least one selected from biphenyl-type epoxy resin, phenol aralkyl-type epoxy resin, phenol linear phenolic epoxy resin, o-cresol linear phenolic epoxy resin, diphenol-type epoxy resin, dinaphthol-type epoxy resin, dicyclopentadiene-type epoxy resin, dihydroanthracene glycol-type epoxy resin, and triphenylmethane-type epoxy resin; the curing agent includes at least one selected from linear phenolic resin, phenol aralkyl resin, naphthol-type phenolic resin, and phenolic resin obtained by reacting hydroxybenzaldehyde, formaldehyde, and phenol. CN102408545A discloses a resin composition for sealing a rare earth permanent magnet coreless energy-saving motor, comprising epoxy resin, phenolic resin, curing accelerator, coupling agent, stress release agent, colorant, flame retardant, release agent, inorganic filler, and glass fiber filler.

[0004] However, none of the aforementioned existing technologies have solved the problem of increasing rotor magnetic flux in motor rotor mounting materials. In particular, since the actual operating temperature of the rotor is in a high-temperature environment of 140-180℃, increasing magnetic flux is even more difficult to achieve at high temperatures. Furthermore, performance testing at high temperatures is necessary to reflect the actual performance of such mounting materials in real-world new energy vehicle applications. Therefore, it is necessary to re-evaluate the various properties of rotor mounting materials at high temperatures to obtain feedback that more closely approximates real-world usage environments, and to make targeted improvements to the mounting materials. Summary of the Invention

[0005] The purpose of this invention is to provide a motor rotor adhesive that can improve rotor magnetic flux without affecting other performance characteristics, thereby giving the rotor better overall magnetic chargeability and expanding the application range of epoxy resin-fixed rotors, particularly in improving magnetic flux characteristics at high temperatures. To achieve the above objective, this invention provides the following technical solution:

[0006] A magnetic adhesive for improving the magnetic flux of a motor rotor, comprising the following raw materials in parts by weight: 5-15 parts epoxy resin, 1-3 parts phenolic resin, 0.5-2 parts curing accelerator, 15-30 parts fused spherical silica, 40-60 parts fused angular silica, 4-10 parts fumed silica, and 3-30 parts magnetic powder; wherein the fused spherical silica has a D50 of 5-9 μm, the fused angular silica has a D50 of 15-21 μm, and the fumed silica has a specific surface area of ​​230-280 m². 2 / g.

[0007] Epoxy resin is used to provide the cohesive force and adhesive strength of the system, ensuring sufficient bonding performance and playing a primary role in fixation. The filler component, mainly composed of inorganic particles, contributes to the overall strength of the filler component under the influence of the fixing components, providing support, hardness, and rigidity. The addition of magnetic material powder enhances the magnetic flux, resulting in better magnetic flux and magnetic induction performance of the rotor after fixation. This improves the overall magnetism of the rotor and reduces losses from the fixing material and interference from the curing material. Compared to fixing methods using magnetic slurry or magnets, the method of this invention is simpler, requires lower processing temperatures, and produces materials with better rigidity, less susceptibility to deformation, and the ability to withstand higher speeds, thus offering greater applicability.

[0008] Furthermore, the magnetic powder includes at least one of sintered NdFeB material and Samarium Cobalt material; the sintered NdFeB material is prepared by calcining NdFeB material at 1100-1300℃ for 3-5 hours, followed by tempering at 500-600℃ for 1-2 hours. The purpose of calcination is to densify the powder particles, eliminate porosity, form a high-density magnet, and improve mechanical strength; the purpose of tempering is to adjust the distribution of grain boundary phases.

[0009] The inventors discovered that directly adding a small amount of magnetic powder to an epoxy resin thermosetting system does not increase the magnetic flux of the fixing material as expected. Possible reasons include poor dispersion of the magnetic powder, incomplete orientation, uneven magnetic flux distribution, and localized demagnetization; or the poor fluidity of silica, making it difficult to increase magnetic flux. Furthermore, the inventors found that at high temperatures, the contribution of magnetic powder to magnetic flux is even less. Adding a large amount of magnetic powder to achieve the desired increase in magnetic flux would drastically increase the cost of such materials, reducing their industrial applicability. Therefore, achieving a high magnetic flux increase with a low amount of magnetic powder is a pressing problem to be solved. The limited increase in magnetic flux from adding magnetic powder at high temperatures is due to the demagnetization of the magnetic powder at high temperatures, and the mismatch between the thermal expansion coefficient of silica (above 150°C) and that of the epoxy resin and magnetic materials. This leads to a loosening of the fixing structure of the magnetic powder, disrupting the original orientation structure and resulting in a decrease in magnetic flux. Increasing the Tg of epoxy resin can mitigate this phenomenon, but this means increasing the crosslinking density of the epoxy resin, making the material more rigid but reducing its toughness. This makes it prone to fatigue failure under high and low temperature cyclic loading, negatively impacting the long-term stability of the rotor fixing material. Therefore, unilaterally increasing the Tg of epoxy resin is not advisable. Furthermore, most epoxy resins currently used are commercial products, and finding suitable high-Tg epoxy resins is not easy. Therefore, using existing epoxy resins while mitigating the adverse effects of epoxy resin thermosetting rotor fixing materials on magnetic flux at high temperatures is of significant importance and commercial value. The inventors unexpectedly discovered that a synergistic blend of three non-magnetic fillers—molten spherical silica of different sizes, molten angular silica, and fumed silica—can improve the magnetic flux enhancement effect of magnetic powder at high temperatures. A significant increase in magnetic flux begins with a magnetic powder content of 3 wt% of the fixing material, whereas without the aforementioned blend of non-magnetic fillers, an addition of more than 10 wt% is required to achieve a suitable magnetic flux enhancement effect. All three fillers are commercially available and inexpensive reagents, facilitating the industrial application of the fixation material of this invention. The reason for the increased magnetic flux resulting from the combination of these three fillers is currently unclear. Possible reasons include the suitable flowability of the blended non-magnetic fillers, and the appropriate size and ratio of spherical and angular silica. Spherical silica particles are generally easier to pack tightly than angular particles, increasing overall density and thus making the magnetic powder more compact, reducing spacing, and increasing magnetic flux. Angular silica forms a supporting structure, reducing sedimentation and improving the arrangement of magnetic powder. The rough surface of angular silica also facilitates interaction with the resin. The addition of fumed silica, synergistically with the spherical / angular silica fillers, forms a multi-scale filling structure, further reducing interfacial stress concentration caused by single particle sizes. However, the amount of fumed silica added needs to be strictly controlled; otherwise, it may have adverse effects.The appropriate combination of spherical and angular silica of suitable size and proportion also needs to consider the flowability of the resin. This invention also adds a certain proportion of silane coupling agent, which can enhance the affinity between the resin and silica and improve the interfacial bonding between the magnetic powder and the resin.

[0010] Further, the magnetic adhesive for the motor rotor comprises the following raw materials in parts by weight: 9-13 parts epoxy resin, 1.2-1.7 parts phenolic resin, 0.8-1.3 parts curing accelerator, 18-26 parts fused spherical silica, 45-55 parts fused angular silica, 5-8 parts fumed silica, 1-3 parts silane coupling agent, and 5-20 parts magnetic powder.

[0011] Preferably, the magnetic powder is a mixture of sintered NdFeB and Samarium Cobalt materials; and when the mixture of sintered NdFeB and Samarium Cobalt materials is added, the raw material of the motor rotor magnetic fixing material further includes 2.2-3.0 parts of boron nitride nanosheets.

[0012] More preferably, in the magnetic powder, the mass ratio of sintered NdFeB material to Samarium Cobalt material is 1:1-3; the boron nitride nanosheets have a size of 100-500 nm and a thickness of 10-50 nm; more preferably, the boron nitride nanosheets have a size of 100-200 nm and a thickness of 10-30 nm.

[0013] Neodymium iron boron (NdFeB) materials possess strong magnetism, high rigidity, and a low coefficient of thermal expansion. However, their Curie temperature is relatively low, resulting in poor temperature stability and a tendency to demagnetize at high temperatures. Furthermore, NdFeB materials are easily oxidized, thus requiring a passivation layer to form on the surface after sintering. Samarium cobalt (SCo) materials exhibit good temperature stability and corrosion resistance. Both materials have their advantages, but sintered NdFeB and SCo materials generally cannot be added simultaneously; otherwise, the inherent disadvantages will be highlighted while the advantages will be diminished. The inventors unexpectedly discovered that adding a small amount of boron nitride nanosheets allows the two magnetic powders to work synergistically, increasing magnetic flux at high temperatures without causing adverse effects. The inventors speculate that the possible reasons are: the boron nitride nanosheets act as a rheology modifier, dispersing in the resin to form a thixotropic network; the thermal expansion coefficient of boron nitride is close to that of NdFeB, reducing interfacial thermal stress during curing and cooling; or both factors may play a role.

[0014] Further, the epoxy resin is selected from at least one of phenolic epoxy resin, bisphenol epoxy resin, biphenyl epoxy resin, and dicyclopentadiene epoxy resin; the phenolic resin is selected from at least one of linear phenolic resin, biphenyl phenolic resin, naphthol phenolic resin, polybenzonitrile phenolic resin, and aralkylphenol phenolic resin; the curing accelerator is selected from imidazole accelerators (such as 2-methylimidazole, 2-ethyl-4-methylimidazole), tertiary amine accelerators (such as triethylamine), and 1,8-diazabicyclo[5.4.0]undec-7-ene.

[0015] The silane coupling agent is an epoxy silane coupling agent, such as γ-glycidoxypropyltrimethoxysilane.

[0016] Furthermore, the magnetic adhesive for improving high-temperature magnetic flux in the motor rotor also includes the following excipients by weight: 0-2 parts ion trapping agent, 0-2 parts release agent, 0-5 parts flame retardant, 0-2 parts toughening agent, and 0-5 parts colorant, wherein the weight of each of the aforementioned excipients is not simultaneously 0. Preferably, the weight of the ion trapping agent is 0.1-1 parts, and / or the weight of the release agent is 0.1-1 parts, and / or the weight of the flame retardant is 1-5 parts, and / or the weight of the toughening agent is 0.1-1 parts, and / or the weight of the colorant is 1-3 parts. The amount and type of excipients are well known to those skilled in the art. For example, the ion scavenger is selected from alumina, magnesium oxide, or combinations thereof; the release agent is selected from lignite wax, fatty acid esters, organosilicon oils, or combinations thereof; the flame retardant is selected from metal hydroxides, oxides of organophosphorus compounds, or combinations thereof; the toughening agent is selected from liquid-phase carboxyl-terminated butadiene-acrylonitrile rubber, liquid-phase hydroxyl-terminated butadiene-acrylonitrile rubber, liquid-phase aminobutadiene-acrylonitrile rubber, liquid polyether diol, liquid polyoxysilane, or combinations thereof; and the colorant is selected from carbon black, iron oxide yellow, and benzidine orange. In a preferred embodiment of the present invention, the total mass of the auxiliary materials does not exceed 10 wt% of the magnetic fixing material of the motor rotor.

[0017] This invention also provides a method for preparing the above-mentioned magnetic adhesive for improving high-temperature magnetic flux in motor rotors, comprising the following steps:

[0018] Weigh each raw material according to the mass fraction, mix them evenly under an inert atmosphere to obtain powder, heat and press them into shape, crush them to obtain powder products with a particle size of 1-10mm; preferably, the particle size of the powder product is 3-5mm.

[0019] The present invention also provides an electric motor rotor, comprising a rotor body, magnets, and the aforementioned magnetic adhesive for fixing the rotor body and magnets. By utilizing the magnetic flux generated after the material is magnetized, interference to the motor caused by the fixing material can be effectively reduced. Attached Figure Description

[0020] Figure 1 is a photograph of adhesive powder compressed into a cylindrical cake.

[0021] Figure 2 is a photograph of the motor rotor after it has been fixed with adhesive. Detailed Implementation

[0022] The solution in this invention will be further described through the following specific embodiments.

[0023] Experiment 1

[0024] This embodiment mainly verifies the effect of the presence of magnetic material powder in the filler component on the system, involving examples containing magnetic material powder and comparative examples without magnetic material powder. The composition of each group is shown in Table 1.

[0025] The D50 of fused spherical silica is 6.2 μm, the D50 of fused angular silica is 17.8 μm, and the BET of fumed silica is 240 μm. 2 / g. The sintered NdFeB magnetic powder is obtained by calcining NdFeB material at 1200℃ for 3 hours, followed by tempering at 600℃ for 2 hours.

[0026] Table 1 Formula for Magnetic Adhesive for Motor Rotor

[0027] In Table 1 above, the colorant is carbon black, the final product is black, the ion scavenger is alumina, and epoxy resins 1 and 2 are two different o-cresol type epoxy resins, where epoxy resin 1 is NPCN-704 (Taiwan Nan Ya Plastics Industrial Co., Ltd.) and epoxy resin 2 is Nan Ya NPCN-703 (Taiwan Nan Ya Plastics Industrial Co., Ltd.). Phenolic resin 1 is bisphenol A type phenolic resin, phenolic resin 2 is polybenzonitrile type phenolic resin, the curing accelerator is 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU), the colorant is carbon black, the ion scavenger is alumina, the toughening agent is liquid carboxyl-terminated butadiene-acrylonitrile rubber, the flame retardant is resorcinol bis(diphenyl phosphate), the release agent is propyl fumarate, and the silane coupling agent is γ-glycidoxypropyltrimethoxysilane.

[0028] The adhesive from Experiment 1 was subjected to performance testing, and the results are shown in Table 2.

[0029] Glass transition temperature: SJ-T11197-2013;

[0030] Coefficient of thermal expansion (α1): SJ-T11197-2013;

[0031] Bending strength: GBT 1449-2005.

[0032] According to the formula in Table 1, weigh each raw material, mix them evenly under a nitrogen atmosphere to obtain powder, heat and press into shape, crush to obtain powder product with a particle size of 3-5mm. Compress the powder into cylindrical cakes (as shown in Figure 1). Preheat the cakes to 90℃ using a high-frequency preheater. Put the preheated cakes into a mold and heat to 190℃ to make the plastic part melt and become fluid. Apply pressure of 10MPa through a hydraulic system to extrude the fluid adhesive into the gap between the magnets and the rotor core (where the magnets are embedded in the rotor core slots according to polarity and preheated to 100℃), ensuring that the material evenly covers the surface of the magnets and fills the slots. The extrusion speed is controlled between 10 and 20 mm / s. The mold temperature is controlled at 150℃ for 10 minutes to form a high-strength cross-linked structure (the finished product is shown in Figure 2). The magnetic flux is tested according to IEC 60404, and the overall magnetic flux of the rotor after magnetization is measured. The magnetic flux test method is IEC 60404, and the test temperature is 180℃.

[0033] Table 2 Performance Test of Magnetic Adhesive for Motor Rotor

[0034] The experimental data above show that adding NdFeB magnetic powder can increase the magnetic flux of the system without significantly affecting the bending strength or coefficient of thermal expansion. It can improve magnetic flux while maintaining good mechanical strength as much as possible. However, aside from mechanical performance and cost considerations, the total mass of the magnetic material added should not exceed 30% of the total mass, preferably not exceeding 20%. It should be noted that the amount of filler components (i.e., the sum of magnetic flux components and non-magnetic flux components) added should be controlled within the range of 75-90% by weight. Excessive addition of filler components will lead to poor internal bonding performance, while insufficient addition will result in insufficient hardness. The compounding of multiple non-magnetic fillers, i.e., molten spherical silica, molten angular silica, and fumed silica mixed in specific sizes and proportions, can synergistically improve the magnetic flux of the fixed material after adding magnetic powder at high temperatures. Comparison of samples 1-7 and 1-12 shows that the addition of epoxy-based silane coupling agents can further improve the magnetic flux.

[0035] Experiment 2

[0036] After comprehensively considering the experimental groups in Experiment 1, experimental groups 1-7 with the best overall performance were selected. Based on this, the amount and type of non-magnetic filler, namely silica, were screened. To adjust the mass ratio and size parameters of the three types of silica—molten spherical silica, molten angular silica, and fumed silica—the ratios and types of other components remained unchanged, as shown in Table 3.

[0037] Among samples 2-5, the D50 of molten spherical silica (a1) is 5.1 μm, and the D50 of molten angular silica (b1) is 15.0 μm; among samples 2-6, the D50 of molten spherical silica (a2) is 8.7 μm, and the D50 of molten angular silica (b2) is 20.3 μm; in comparative example 5, the D50 of molten spherical silica (a3) ​​is 4.2 μm, and the D50 of molten angular silica (b3) is 13.5 μm; in comparative example 6, the D50 of molten spherical silica (a4) is 10.0 μm, and the D50 of molten angular silica (b4) is 25.0 μm.

[0038] Table 3 Formula for Magnetic Adhesive for Motor Rotors

[0039] The performance of the magnetic fixing materials for each motor rotor in Table 3 was tested, and the results are shown in Table 4. The glass transition temperature and coefficient of thermal expansion are very similar, so they are not listed in Table 4.

[0040] Table 4 Performance Test of Magnetic Adhesive for Motor Rotor

[0041] Based on the above experimental results, adjusting the composition of silica can achieve relatively good magnetic flux without changing the amount of magnetic material added. However, it is necessary to control the particle size of molten spherical silica and molten angular silica in order to effectively improve the magnetic flux of the adhesive at high temperatures.

[0042] Experiment 3

[0043] Everything else was the same as in Experiment 1. Experiment 3 used a mixture of sintered NdFeB and Samarium Cobalt magnetic powders. The formulation is shown in Table 5 below. The boron nitride nanosheets used were approximately 300 ± 50 nm in size and approximately 30 nm thick.

[0044] Table 5 Formula for Magnetic Adhesive for Motor Rotors

[0045] The performance of the magnetic fixing materials for each motor rotor in Table 5 was tested, and the results are shown in Table 6. The differences in glass transition temperature and coefficient of thermal expansion are very small, so they are not listed in Table 6.

[0046] Table 6 Performance Test of Magnetic Adhesive for Motor Rotor

[0047] It can be seen that adding sintered NdFeB magnetic powder and Samarium Cobalt magnetic powder at the same time will actually reduce the magnetic flux. It is necessary to add boron nitride nanosheets in combination to significantly increase the high-temperature magnetic flux.

Claims

1. A magnetic adhesive for improving high-temperature magnetic flux in motor rotors, characterized in that, The raw materials comprise the following parts by weight: 5-15 parts epoxy resin, 1-3 parts phenolic resin, 0.5-2 parts curing accelerator, 15-30 parts fused spherical silica, 40-60 parts fused angular silica, 4-10 parts fumed silica, and 3-30 parts magnetic powder; wherein the fused spherical silica has a D50 of 5-9 μm, the fused angular silica has a D50 of 15-21 μm, and the fumed silica has a specific surface area of ​​230-280 m². 2 / g.

2. The magnetic adhesive for motor rotors according to claim 1, characterized in that, The magnetic powder includes at least one of sintered NdFeB material and Samarium Cobalt material.

3. The magnetic adhesive for motor rotors according to claim 2, characterized in that, The sintered NdFeB material is prepared by calcining NdFeB material at 1100-1300℃ for 3-5 hours, followed by tempering at 500-600℃ for 1-2 hours.

4. The magnetic adhesive for motor rotors according to claim 1, characterized in that, The raw materials include the following parts by weight: 9-13 parts epoxy resin, 1.2-1.7 parts phenolic resin, 0.8-1.3 parts curing accelerator, 18-26 parts fused spherical silica, 45-55 parts fused angular silica, 5-8 parts fumed silica, 1-3 parts silane coupling agent, and 5-20 parts magnetic powder.

5. The magnetic adhesive for motor rotors according to claim 1, characterized in that, The magnetic powder comprises a mixture of sintered NdFeB and Samarium Cobalt materials; and when the mixture of sintered NdFeB and Samarium Cobalt materials is added, the raw material of the motor rotor magnetic adhesive further comprises 2.2-3.0 parts by weight of boron nitride nanosheets.

6. The magnetic adhesive for motor rotors according to claim 5, characterized in that, In the magnetic powder, the mass ratio of sintered NdFeB material to Samarium Cobalt material is 1:1-3; the boron nitride nanosheets have a size of 100-500 nm and a thickness of 10-50 nm.

7. The magnetic adhesive for motor rotors according to claim 1, characterized in that, The epoxy resin is selected from at least one of phenolic epoxy resin, bisphenol epoxy resin, biphenyl epoxy resin, and dicyclopentadiene epoxy resin; the phenolic resin is selected from at least one of linear phenolic resin, biphenyl phenolic resin, naphthol phenolic resin, polybenzonitrile phenolic resin, and aralkylphenol phenolic resin; the curing accelerator is selected from imidazole accelerators and tertiary amine accelerators.

8. The magnetic adhesive for motor rotors according to claim 1, characterized in that, It also includes the following excipients by weight: 0-2 parts ion capture agent, 0-2 parts release agent, 0-5 parts flame retardant, 0-2 parts toughening agent, and 0-5 parts colorant, wherein the aforementioned excipients by weight are not all 0 at the same time.

9. A method for preparing the magnetic adhesive for improving high-temperature magnetic flux of a motor rotor according to any one of claims 1-8, characterized in that, Includes the following steps: Weigh each raw material according to the mass fraction, mix them evenly under an inert atmosphere to obtain powder, heat and press them into shape, crush them to obtain powder products with a particle size of 1-10mm.

10. A motor rotor, characterized in that, The motor rotor includes a rotor body, magnets, and a magnetic adhesive for fixing the rotor body and magnets as described in any one of claims 1-8.

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