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

Abstract

The invention relates to the field of motor adhesives, in particular to a motor rotor magnetic adhesive for improving high-temperature magnetic flux and a motor rotor.The motor rotor magnetic adhesive is prepared from, by mass, 5-15 parts of epoxy resin, 1-3 parts of phenolic resin, 0.5-2 parts of curing accelerator and 15-30 parts of fused spherical silicon dioxide. 40-60 parts of fused angular silicon dioxide, 4-10 parts of fumed silica, 1-3 parts of a silane coupling agent and 5-30 parts of magnetic powder; the D50 of the fused spherical silica is 5-9 [mu] m, the D50 of the fused angular silica is 15-21 [mu] m, and the specific surface area of the fumed silica is 230-280 m < 2 > / g. The magnetic material powder is used as a part of the solid filler and is matched with the silicon dioxide filler with the specific size, so that the high-temperature magnetic flux of the whole material is improved, and meanwhile, good mechanical strength is kept.

Description

Technical Field

[0001] The invention relates to the field of motor adhesives, and in particular to a motor rotor magnetic adhesive for improving high-temperature magnetic flux and a motor rotor. Background Art

[0002] Under the guidance of global green energy, the gradual maturity of the technology of the new energy vehicle industry chain has given the market a better choice. Among them, for most new energy vehicles, permanent magnet motors, the fixing methods of magnetic steel and iron core are key processes. Several common methods include glue fixing, injection molding fixing and rivet point fixing. Glue fixing is an early method used to fix the magnetic steel in the rotor iron core through epoxy glue, etc., but the fixing performance is not stable, and the strength loss over time is large. This method has basically been eliminated and may only be used in small batch proofing experiments. Injection molding fixing is a new technology developed in recent years. Injection molding material is injected around the magnetic steel to form a fixation, providing more stable performance. The mainstream magnetic fixing materials for 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 is higher than 17000rpm, thermosetting materials have become the first choice for magnetic steel fixing materials. Using epoxy resin to fix the motor rotor is a common method. Thermosetting epoxy resin has good toughness, impact resistance, vibration resistance and corrosion resistance, and has excellent bonding effect, so it has a wide range of applications. However, epoxy resin will cause magnetic flux loss of the rotor during the filling process, and its use in some scenarios is subject to certain restrictions. At present, there is no method to fix the rotor magnetic flux. In theory, the directional addition of high-permeability magnetic powder to epoxy molding compound (EMC) may enhance the continuity of the magnetic circuit, thereby improving the overall magnetic flux density. However, experiments have found that directly adding magnetic powder has little effect on improving the magnetic flux. There are many possible reasons, such as the interface bonding strength and dispersion uniformity between magnetic powder and epoxy resin directly affect the stability of magnetic permeability; it may also be due to the fluidity of non-magnetic fillers, dense packing mode, etc., which will affect the magnetic flux.

[0003] CN103081301B discloses a rotor, comprising a rotor core, fixedly arranged on a rotating shaft and provided with a plurality of holes arranged along the peripheral portion of the rotating shaft; a magnet, inserted into the hole; a fixing member, formed by curing a fixing resin composition filled in a separation portion between the hole and the magnet, and arranged on at least one of the side walls of the magnet located on the inner peripheral side of the rotor core to fix the magnet; the fixing resin composition comprises: a thermosetting resin (A) containing an 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% by mass of the total value of the fixing resin composition, the concentration of ionic impurities relative to the fixing resin composition is 500 ppm or less, and the ionic impurities are at least one selected from alkali metal ions, alkaline earth metal ions and halogen ions. CN104136532A discloses a resin composition for fixing a rotor, comprising a thermosetting resin containing an epoxy resin, a curing agent and an inorganic filler; the epoxy resin comprises at least one selected from biphenyl epoxy resin, phenol aralkyl epoxy resin, phenol novolac epoxy resin, o-cresol novolac epoxy resin, diphenol epoxy resin, dinaphthol epoxy resin, dicyclopentadiene epoxy resin, dihydroanthracene diol epoxy resin and triphenylmethane epoxy resin; the curing agent comprises at least one selected from novolac resin, phenol aralkyl resin, naphthol 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 an epoxy resin, a phenolic resin, a curing accelerator, a coupling agent, a stress release agent, a colorant, a flame retardant, a release agent, an inorganic filler and a glass fiber filler.

[0004] However, none of the above existing technologies solves the defect that it is difficult for motor rotor fixing materials to improve the rotor magnetic flux. In particular, since the actual operating temperature of the rotor is in a high temperature environment of 140-180°C, it is even more difficult to improve the magnetic flux in a high temperature environment. For the use of such fixing materials, performance tests at high temperatures can reflect the actual use of new energy vehicles. Therefore, it is necessary to re-evaluate the various performances of rotor fixing materials at high temperatures, provide feedback that is closer to the actual use environment, and make targeted improvements to the fixing materials. Summary of the invention

[0005] The purpose of the present invention is to provide a motor rotor adhesive that can improve the rotor magnetic flux without affecting other properties, so that the rotor as a whole has better magnetization properties, so as to expand the application scope of epoxy resin fixed rotor, especially to improve the characteristics of magnetic flux at high temperature. To achieve the above purpose, the present invention provides the following technical solutions: A motor rotor magnetic adhesive for improving high-temperature magnetic flux, comprising the following raw materials in parts by mass: 5-15 parts of epoxy resin, 1-3 parts of phenolic resin, 0.5-2 parts of curing accelerator, 15-30 parts of fused spherical silica, 40-60 parts of fused angular silica, 4-10 parts of fumed silica, and 3-30 parts of magnetic powder; 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 m 2 / g.

[0006] Epoxy resin is used to provide the cohesion and bonding strength of the system, so that the system contains sufficient bonding properties and plays a major fixing effect, while the filler component is mainly inorganic particles. Under the action of the fixing component, the filler component of the present invention can form an overall strength, provide support, hardness and rigidity. The added magnetic material powder can improve the magnetic flux, so that the rotor has better magnetic flux and magnetic induction performance after fixing, thereby improving the magnetism of the rotor as a whole, reducing the loss of the fixing material to the rotor and the interference of the curing material to the magnetism. Compared with the fixing method of magnetic powder slurry or magnetic steel, the method of the present invention has a simple process, the required processing temperature is low, and the material has good rigidity, is not easy to change, and can withstand a higher rotation speed, so it has a better application prospect.

[0007] Furthermore, the magnetic powder includes at least one of sintered NdFeB material and SmCo material; the sintered NdFeB material is prepared by calcining the NdFeB material at 1100-1300°C for 3-5h, and then tempering it at 500-600°C for 1-2h. The purpose of calcination is to densify the powder particles, eliminate pores, form a high-density magnet, and improve mechanical strength; the purpose of tempering is to adjust the grain boundary phase distribution.

[0008] The inventors found that directly adding a small amount of magnetic powder to the epoxy resin thermosetting system does not improve the magnetic flux of the fixed material as expected. Possible reasons are that the magnetic powder has poor dispersion, the orientation has not reached the ideal state, the magnetic flux is unevenly distributed, and local demagnetization occurs; it may also be due to the poor fluidity of silica, which makes it difficult to achieve the purpose of increasing the magnetic flux. In addition, the inventors also found that under high temperature conditions, the contribution of adding magnetic powder to the magnetic flux is even less. If the purpose of increasing the magnetic flux is to be achieved, adding a large amount of magnetic powder will cause a significant increase in the cost of such materials and a decrease in industrial practical value. Therefore, it is an urgent problem to achieve a higher magnetic flux increase with a low amount of magnetic powder. The addition of magnetic powder has limited effect on the improvement of magnetic flux in a high temperature environment. This is because the magnetic powder will demagnetize at high temperatures, and the thermal expansion coefficient of silica at high temperatures >150°C does not match that of epoxy resin and magnetic materials, resulting in the relaxation of the fixed structure of the fixed magnetic powder, destroying the original orientation structure, and reducing the magnetic flux. Increasing the Tg of epoxy resin can improve this phenomenon, but this means increasing the crosslinking density of epoxy resin, making the material more rigid, resulting in poor toughness, easy fatigue failure under high and low temperature cycle loads, and adversely affecting the long-term stability of the rotor fixing material. Therefore, unilaterally increasing the Tg of epoxy resin is not desirable. Moreover, most of the epoxy resins currently used are commercial products, and it is not easy to find a suitable high Tg epoxy resin. Therefore, when using existing epoxy resins, it is also possible to reduce the adverse effects of epoxy resin thermosetting rotor fixing materials on magnetic flux at high temperatures, which has important significance and commercial value. The inventor unexpectedly found that the three non-magnetic fillers, namely, fused spherical silica of different sizes, fused angular silica, and fumed silica, are synergistically compounded and work together to improve the magnetic powder's effect on the magnetic flux under high temperature environments, so that the magnetic powder addition amount accounts for 3wt% of the fixing material. The effect of significantly improving the magnetic flux begins, and if the above-mentioned compounded non-magnetic fillers are not suitable, an addition amount of more than 10wt% is required to have a suitable effect of improving the magnetic flux. The three fillers are all common and inexpensive reagents available on the market, which facilitate the industrial application of the fixing material of the present invention. At present, the reason why the combination of the three fillers improves the magnetic flux is unknown. The possible reason is that the compounded non-magnetic filler has suitable fluidity, and the combination of spherical silica and angular silica of suitable size and proportion, among which spherical silica particles are usually easier to stack tightly than angular particles, improving the overall density, so that the magnetic powder is more compact, reducing the spacing, and increasing the magnetic flux; angular silica forms a supporting structure, reduces sedimentation, and improves the arrangement of magnetic powder. The rough surface of angular silica is also conducive to the interaction between the resin. The addition of fumed silica, in conjunction with spherical / angular silica fillers, forms a multi-scale filling structure, further reducing the interfacial stress concentration caused by a single particle size. However, the amount of fumed silica added needs to be strictly controlled, otherwise it will have an adverse effect.The combination of spherical silica and angular silica of appropriate size and proportion also needs to consider the fluidity coordination with the resin. The present invention also adds a certain proportion of silane coupling agent to enhance the affinity between the resin and silica and improve the interface bonding between the magnetic powder and the resin.

[0009] Furthermore, the motor rotor magnetic adhesive comprises the following raw materials in parts by mass: 9-13 parts of epoxy resin, 1.2-1.7 parts of phenolic resin, 0.8-1.3 parts of curing accelerator, 18-26 parts of fused spherical silica, 45-55 parts of fused angular silica, 5-8 parts of fumed silica, 1-3 parts of silane coupling agent, and 5-20 parts of magnetic powder.

[0010] Preferably, the magnetic powder is a mixture of sintered NdFeB material and SmCo material; and when the mixture of sintered NdFeB material and SmCo material is added, the raw material of the motor rotor magnetic fixing material also includes 2.2-3.0 parts of boron nitride nanosheets.

[0011] More preferably, in the magnetic powder, the mass ratio of sintered NdFeB material to SmCo material is 1:1-3; the size of boron nitride nanosheets is 100-500nm, and the thickness is 10-50nm; more preferably, the size of boron nitride nanosheets is 100-200nm, and the thickness is 10-30nm.

[0012] NdFeB material itself has strong magnetism, strong rigidity, and low thermal expansion coefficient, but its Curie temperature is low, the temperature stability is poor, and it is easy to demagnetize at high temperature; in addition, NdFeB material is easily oxidized, so it is used to form a passivation layer on the surface after sintering. Samarium cobalt material has good temperature stability and corrosion resistance. The two materials have their own advantages in performance, but sintered NdFeB material and SmCo material generally cannot be added at the same time, otherwise the characteristic disadvantages will be highlighted, but the advantages will not be obvious. The inventor unexpectedly found that by adding a small amount of boron nitride nanosheets, the two magnetic powders can be used together to increase the magnetic flux at high temperature without any adverse effects. The inventor speculates that the possible reason is that boron nitride nanosheets act as a rheology regulator and disperse in the resin to form a thixotropic network; it may also be because the thermal expansion coefficient of boron nitride is close to that of NdFeB, which can reduce the interfacial thermal stress during curing and cooling; or both factors play a role.

[0013] Furthermore, 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, naphthyl 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.

[0014] The silane coupling agent is an epoxy silane coupling agent, such as γ-glycidyloxypropyltrimethoxysilane.

[0015] Furthermore, the motor rotor magnetic adhesive for improving high temperature magnetic flux also includes the following auxiliary materials in parts by weight: 0-2 parts of ion capture agent, 0-2 parts of mold release agent, 0-5 parts of flame retardant, 0-2 parts of toughening agent, 0-5 parts of colorant, and the parts by weight of the aforementioned auxiliary materials are not all 0. Preferably, the part by weight of the ion capture agent is 0.1-1 parts, and / or the part by weight of the mold release agent is 0.1-1 parts, and / or the part by weight of the flame retardant is 1-5 parts, and / or the part by weight of the toughening agent is 0.1-1 parts, and / or the part by weight of the colorant is 1-3 parts. The amount and type of auxiliary materials are well known to those skilled in the art. For example, the ion capture agent is selected from aluminum oxide, magnesium oxide or a combination thereof; the mold release agent is selected from lignite wax, fatty acid ester, silicone oil or a combination thereof; the flame retardant is selected from metal hydroxide, oxide of organic phosphorus compound or a combination thereof; the toughening agent is selected from liquid carboxyl-terminated nitrile rubber, liquid hydroxyl-terminated nitrile rubber, liquid amino-terminated nitrile rubber, liquid polyether diol, liquid polyoxysilane and a combination thereof; the colorant is selected from carbon black, iron oxide yellow, benzidine orange. In a preferred technical solution of the present invention, the total mass of the auxiliary materials does not exceed 10wt% of the magnetic fixing material of the motor rotor.

[0016] The present invention also provides a method for preparing the above-mentioned motor rotor magnetic adhesive for improving high-temperature magnetic flux, comprising the following steps: The raw materials are weighed according to their mass parts, mixed evenly under an inert atmosphere to obtain a powder, heated and pressed into shape, and crushed to obtain a powder product with a particle size of 1-10 mm; preferably, the particle size of the powder product is 3-5 mm.

[0017] The present invention also provides a motor rotor, comprising a rotor body, a magnetic steel, and the magnetic adhesive for fixing the rotor body and the magnetic steel. The magnetic flux formed by the material after magnetization can effectively reduce the interference of the fixing material on the motor. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a photo of adhesive powder compressed into cylindrical cakes; Figure 2 This is a photo of the entire motor rotor after being fixed with adhesive. DETAILED DESCRIPTION

[0019] The scheme of the present invention is further described through the following specific implementation methods.

[0020] Experiment 1 In this example, the effect of the presence of magnetic material powder in the filler component on the system is mainly verified, involving an example containing magnetic material powder and a comparative example not containing magnetic material powder. The distribution ratio of each group is shown in Table 1.

[0021] 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 The sintered NdFeB magnetic powder is obtained by calcining NdFeB material at 1200° C. for 3 hours and then tempering at 600° C. for 2 hours.

[0022] Table 1 Formula of magnetic adhesive for motor rotor

[0023] In the above Table 1, the colorant is carbon black, the final product is black, the ion scavenger is aluminum oxide, epoxy resins 1 and 2 are two different o-cresol epoxy resins, wherein epoxy resin 1 is NPCN-704 (Nan Ya Plastics Co., Ltd.), and epoxy resin 2 is Nan Ya NPCN-703 (Nan Ya Plastics Co., Ltd.). Phenolic resin 1 is bisphenol A type phenolic resin, phenolic resin 2 is polybenzonitrile type phenolic resin, curing accelerator is 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU), colorant is carbon black, the ion scavenger is aluminum oxide, toughening agent is liquid carboxyl-terminated nitrile rubber, flame retardant is resorcinol bis(diphenyl phosphate), release agent is propyl fumarate, and silane coupling agent is γ-glycidyloxypropyl trimethoxysilane.

[0024] The performance of the adhesive in Experiment 1 was tested, and the results are shown in Table 2.

[0025] Glass transition temperature: SJ-T11197-2013; Thermal expansion coefficient (α1): SJ-T11197-2013; Flexural strength: GBT 1449-2005.

[0026] According to the formula in Table 1, the raw materials were weighed, mixed evenly under nitrogen atmosphere to obtain powder, heated and pressed into shape, crushed to obtain a powder product with a particle size of 3-5 mm, and the powder was compressed into a cylindrical cake (as shown below). Figure 1), the high-frequency preheating machine preheats the cake to 90°C, puts the preheated cake into the mold and heats it to 190°C to make its plastic part melt and have fluidity, applies a pressure of 10MPa through the hydraulic system, and squeezes the fluid adhesive into the gap between the magnetic steel and the rotor core (where the magnetic steel is embedded in the rotor core slot according to polarity arrangement and preheated to 100°C), ensuring that the material evenly covers the surface of the magnetic steel and fills the slot, and the extrusion speed is controlled between 10~20 mm / s. The mold temperature is controlled at 150°C for 10 minutes to form a high-strength cross-linked structure (finished product such as Figure 2 ). The magnetic flux test refers to IEC60404, and the magnetic flux of the rotor as a whole is measured after magnetization. The magnetic flux test method is IEC 60404, and the test temperature is 180℃.

[0027] Table 2 Motor rotor magnetic adhesive performance test

[0028] It can be seen from the above experimental data that after adding NdFeB magnetic powder, the magnetic flux of the system can be improved, and there is no obvious effect on the bending strength and thermal expansion coefficient. The magnetic flux can be improved while maintaining good mechanical strength as much as possible. However, considering the mechanical properties and cost, the overall added mass of the magnetic material should not exceed 30% of the total mass, preferably not more than 20% of the total mass. It should be noted that in the above materials, the amount of filler component (i.e. the sum of the magnetic flux component and the non-magnetic flux component) added should be controlled within the specific gravity range of 75-90%. If the amount of filler component added is too much, the internal bonding performance of the system will deteriorate, and too little addition will result in insufficient hardness of the system. The compounding of multiple non-magnetic fillers, i.e., fused spherical silica, fused angular silica, and fumed silica in a specific size and specific ratio can synergistically improve the magnetic flux of the fixed material at high temperature after adding magnetic powder. By comparing samples 1-7 and 1-12, it is found that the addition of epoxy silane coupling agent can further improve the magnetic flux.

[0029] Experiment 2 After comprehensive consideration of the experimental groups in Experiment 1, the experimental groups 1-7 with the best comprehensive performance were selected, and on this basis, the amount and type of non-magnetic filler, that is, silica, were screened. The mass ratio of fused spherical silica, fused angular silica, and fumed silica, as well as parameters such as size, were adjusted, and the ratios and types of the other components remained unchanged, as shown in Table 3.

[0030] Among them, in samples 2-5, the D50 of the molten spherical silica (a1) is 5.1 μm, and the D50 of the molten angular silica (b1) is 15.0 μm; in samples 2-6, the D50 of the molten spherical silica (a2) is 8.7 μm, and the D50 of the molten angular silica (b2) is 20.3 μm; in sample comparison example 5, the D50 of the molten spherical silica (a3) ​​is 4.2 μm; the D50 of the molten angular silica (b3) is 13.5 μm; in sample comparison example 6, the D50 of the molten spherical silica (a4) is 10.0 μm, and the D50 of the molten angular silica (b4) is 25.0 μm.

[0031] Table 3 Formula of magnetic adhesive for motor rotor

[0032] The performance of the motor rotor magnetic fixing materials in Table 3 was tested, and the results are shown in Table 4. The differences in glass transition temperature and thermal expansion coefficient are very small, so they are not listed in Table 4.

[0033] Table 4 Motor rotor magnetic adhesive performance test

[0034] Through the above experimental results, by adjusting the composition of silica, relatively good magnetic flux can be obtained without changing the amount of magnetic material added. However, the particle size of molten spherical silica and molten angular silica needs to be controlled to effectively improve the magnetic flux of the adhesive at high temperature.

[0035] Experiment 3 The other conditions are the same as those in Experiment 1. Experiment 3 attempts to use a mixture of sintered NdFeB magnetic powder and SmCo magnetic powder. The formula is shown in Table 5. The size of the boron nitride nanosheets used is about 300±50 nm and the thickness is about 30 nm.

[0036] Table 5 Formula of motor rotor magnetic adhesive

[0037] The performance of the motor rotor magnetic fixing materials in Table 5 was tested, and the results are shown in Table 6. The differences in glass transition temperature and thermal expansion coefficient are very small, so they are not listed in Table 6.

[0038] Table 6 Motor rotor magnetic adhesive performance test

[0039] It can be seen that the simultaneous addition of sintered NdFeB magnetic powder and SmCo magnetic powder will reduce the magnetic flux. The addition of boron nitride nanosheets is required to significantly increase the high-temperature magnetic flux.

Claims

1. A magnetic adhesive for improving high temperature magnetic flux of a motor rotor, characterized in that: The invention comprises the following raw materials in parts by weight: 5-15 parts of epoxy resin, 1-3 parts of phenolic resin, 0.5-2 parts of curing accelerator, 15-30 parts of fused spherical silica, 40-60 parts of fused angular silica, 4-10 parts of fumed silica, and 3-30 parts of magnetic powder; 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 m 2 / g.

2. The motor rotor magnetic adhesive according to claim 1, characterized in that: The magnetic powder includes at least one of sintered NdFeB material and SmCo material.

3. The motor rotor magnetic adhesive according to claim 2, characterized in that: The sintered NdFeB material is prepared by calcining the NdFeB material at 1100-1300° C. for 3-5 hours and then tempering it at 500-600° C. for 1-2 hours.

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

5. The motor rotor magnetic adhesive according to claim 1, characterized in that: The magnetic powder includes a mixture of sintered NdFeB material and SmCo material; and when the mixture of sintered NdFeB material and SmCo material is added, the raw material of the motor rotor magnetic adhesive also includes 2.2-3.0 parts by mass of boron nitride nanosheets.

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

7. The motor rotor magnetic adhesive 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, naphthyl phenolic resin, polybenzonitrile phenolic resin, and aralkylphenol phenolic resin; the curing accelerator is selected from imidazole accelerators and tertiary amine accelerators.

8. The motor rotor magnetic adhesive according to claim 1, characterized in that: The invention also includes the following auxiliary materials in parts by weight: 0-2 parts of ion capture agent, 0-2 parts of mold release agent, 0-5 parts of flame retardant, 0-2 parts of toughening agent, 0-5 parts by weight of colorant, and the parts by weight of the aforementioned auxiliary materials are not all 0 at the same time.

9. The method for preparing the magnetic adhesive for improving high temperature magnetic flux of a motor rotor according to any one of claims 1 to 8, characterized in that: The following steps are involved: The raw materials are weighed according to their mass parts, mixed evenly under an inert atmosphere to obtain powder, heated and pressed into shape, and crushed to obtain a powder product with a particle size of 1-10 mm.

10. A motor rotor, characterized in that: The invention comprises a rotor body, a magnetic steel, and a motor rotor magnetic adhesive as described in any one of claims 1 to 8 for fixing the rotor body and the magnetic steel.

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