Resin applied to winding of carbon fiber of motor rotor and preparation method thereof

Abstract

The application relates to the technical field of high polymer composite materials, and particularly discloses a resin applied to motor rotor carbon fiber winding and a preparation method thereof. The resin comprises the following raw materials: 40-60 parts of a tetrafunctional phenolic epoxy resin, 20-40 parts of a biphenyl type epoxy resin, 15-20 parts of a core-shell rubber, 0.1-0.2 parts of triphenylphosphine, 20-25 parts of a curing agent, 0.5-1 part of an accelerator, 3-5 parts of nano fillers, 1-2 parts of a silane coupling agent and 5-8 parts of an active diluent. The resin prepared by the application has excellent high-temperature resistance and high elongation at break, and can be applied to motor rotor carbon fiber winding.

Description

A resin for use in carbon fiber winding of motor rotor and its preparation method Technical Field

[0001] This invention relates to the technical field of polymer composite materials, and in particular to a resin used for carbon fiber winding of motor rotors and its preparation method. Background Technology

[0002] In the field of new energy, carbon fiber has a wide range of applications. For example, carbon fiber sheared webs are used in the blades of megawatt-level large wind turbines, carbon fiber brackets are used in photovoltaic products, and carbon fiber is used to manufacture lightweight bodies for new energy vehicles. Compared to steel, carbon fiber has only 23% of the density of steel, but its tensile strength is 7 to 12 times that of steel. For automobiles, carbon fiber can reduce vehicle weight to increase driving range and improve body strength to achieve higher safety. In fact, some well-known sports cars have long used carbon fiber bodies to reduce weight and increase speed. In the field of new energy vehicles, permanent magnet motors, as the heart of new energy vehicles, also use carbon fiber. A certain type of electric vehicle uses carbon fiber bushings on the rotor of its permanent magnet motor, reducing the motor's weight, improving the motor's energy conversion efficiency, increasing motor torque, and extending the motor's service life—achieving multiple benefits. This will undoubtedly lead to a more profound development in the research and application of carbon fiber bushings for motors in the new energy vehicle field, creating more technological miracles and market opportunities.

[0003] Currently, there are not many resins available on the market for carbon fiber winding of motor rotors, and they are mainly imported. However, the resin system, which is a key substrate for carbon fiber winding molding, still faces significant technical bottlenecks. The glass transition temperature (Tg) of currently available commercial epoxy resins is generally below 180℃, which may lead to thermal deformation at the continuous operating temperature of the motor (150-200℃), causing instability in the rotor's dynamic balance. Furthermore, the elongation at break of typical carbon fiber winding resins is less than 2%, making it difficult to meet the requirements for resisting microcrack propagation under high-speed rotor rotation conditions (>15000rpm).

[0004] Therefore, it is necessary to develop resins with high temperature resistance and high elongation at break to meet the requirements of motor rotors. Summary of the Invention

[0005] In order to improve the high temperature resistance and high elongation at break of the resin used for carbon fiber winding of motor rotors, this application provides a resin used for carbon fiber winding of motor rotors and a method for preparing the same.

[0006] Firstly, this application provides a resin for use in the winding of carbon fiber in an electric motor rotor, employing the following technical solution:

[0007] A resin for use in carbon fiber winding of motor rotors comprises the following raw materials in parts by weight: 40-60 parts of tetrafunctional phenolic epoxy resin, 20-40 parts of biphenyl epoxy resin, 15-20 parts of core-shell rubber, 0.1-0.2 parts of triphenylphosphine, 20-25 parts of curing agent, 0.5-1 part of accelerator, 3-5 parts of nanofiller, 1-2 parts of silane coupling agent, and 5-8 parts of reactive diluent.

[0008] By employing the above technical solutions, during the curing process, the tetrafunctional phenolic epoxy resin forms a three-dimensional dense network with its tetrafunctional structure, while the biphenyl groups of the biphenyl-type epoxy resin form an interpenetrating network with this three-dimensional dense network. Therefore, the blending of the two epoxy resins optimizes the balance between crosslinking density and molecular chain rigidity, synergistically increasing the glass transition temperature (Tg). Triphenylphosphine catalyzes the ring-opening reaction between the epoxy groups and the rubber shell, forming chemical bridges, enhancing the interfacial bonding between the toughening phase and the matrix, inhibiting high-temperature phase separation, and improving elongation at break. Silane coupling agents improve the compatibility between the nanofillers and the resin; the high specific surface area of ​​the nanofillers adsorbs molecular chains, inhibiting chain relaxation at high temperatures and increasing the glass transition temperature (Tg). The curing agent reacts with the epoxy resin, the accelerator lowers the activation energy of the curing reaction, and the reactive diluent provides toughening. Therefore, a resin with excellent high-temperature resistance and high elongation at break can be obtained, which can be applied to carbon fiber winding for motor rotors.

[0009] In one specific implementation, the core-shell rubber is a core-shell butadiene rubber or a core-shell silicone rubber.

[0010] By adopting the above technical solutions, the epoxy shell of the core-shell butadiene rubber can bond with the epoxy resin, inhibiting interfacial debonding. The butadiene core has a low elastic modulus, absorbing energy under external force, which helps to improve the elongation at break. The shell of the core-shell silicone rubber is bonded with the epoxy resin, ensuring interfacial stability at high temperatures. The silicone core remains elastic at high temperatures, which also helps to improve the elongation at break.

[0011] In one specific embodiment, the curing agent comprises methylhexahydrophthalic anhydride and diaminodiphenyl sulfone in a weight ratio of (3.5-4.5):1.

[0012] By adopting the above technical solution, this application found that the curing agent with the above-mentioned ratio can balance high-temperature resistance and elongation at break. This may be because methylhexahydrophthalic anhydride introduces a flexible six-membered ring structure, reducing the rigidity of the crosslinking network and increasing the elongation at break, while the sulfone group and aromatic amine structure of diaminodiphenyl sulfone enhance thermal stability, which helps to increase the glass transition temperature (Tg).

[0013] In one specific implementation, the promoter is benzyldimethylamine or 2-ethyl-4-methylimidazole.

[0014] By employing the above technical solution, benzyl dimethylamine can efficiently initiate the epoxy-anhydride ring-opening reaction at 80-120℃, thus shortening the pre-curing time. During the post-curing stage at 180℃, 2-ethyl-4-methylimidazole can deeply promote the reaction of residual epoxy groups, increase the crosslinking density, and thereby raise the glass transition temperature (Tg).

[0015] In one specific implementation, the nanofiller is nano-silica or carbon nanotubes.

[0016] By employing the above technical solution, the surface of nano-silica, after being modified with a silane coupling agent, forms chemical bonds with epoxy resin, reducing stress concentration at the carbon fiber-resin interface, restricting molecular chain movement at high temperatures, and increasing the glass transition temperature (Tg). Carbon nanotubes then experience pull-out or breakage during crack propagation, thus increasing elongation at break.

[0017] In one specific implementation, the active diluent is cashew phenol glycidyl ether.

[0018] By adopting the above technical solution, the C15 long chain of cashew phenol acts as an "internal plasticizer," introducing flexible segments into the crosslinking network, which helps to improve the elongation at break. Moreover, the benzene ring structure of cashew phenol forms a conjugated system with the aromatic ring of epoxy resin, inhibiting the movement of molecular chain segments at high temperatures and having little impact on the glass transition temperature of the cured resin.

[0019] In one specific implementation, the resin used for winding the carbon fiber of the motor rotor also includes polyetheretherketone (PEEK) micron powder.

[0020] By adopting the above technical solution, polyetheretherketone micro powder has a high melting point and glass transition temperature. Even if the epoxy resin softens partially at high temperature, the polyetheretherketone micro powder can still maintain rigidity, suppress the thermal deformation of the overall material, and further improve the high temperature resistance.

[0021] Secondly, this application provides a method for preparing a resin used in the winding of carbon fiber in an electric motor rotor, which employs the following technical solution:

[0022] A method for preparing a resin for use in carbon fiber winding of an electric motor rotor includes the following steps:

[0023] A mixture of tetrafunctional phenolic epoxy resin and biphenyl epoxy resin was heated to 80-90℃, and core-shell rubber was added. The mixture was kept warm and stirred until homogeneous under nitrogen protection to obtain a homogeneous premix.

[0024] The homogeneous premix was heated to 115-125℃, triphenylphosphine was added, and the reaction was maintained at this temperature for 1.8-2.3 hours. The mixture was then cooled to 50-60℃ to obtain the premixed resin.

[0025] The nanofiller and silane coupling agent were mixed evenly, added to the premixed resin, and ground until homogeneous to obtain a resin-filler mixture.

[0026] The curing agent and accelerator are mixed evenly and added to the resin-filler mixture. The mixture is stirred evenly at ≤60℃, and the reactive diluent is added. After mixing evenly and degassing, a resin for use in carbon fiber winding of motor rotors is obtained.

[0027] By employing the above technical solutions, heating at 80-90℃ reduces resin viscosity, ensuring uniform dispersion of the core-shell rubber and avoiding phase separation caused by cold mixing. A temperature of 115-125℃ matches the epoxy ring-opening activation energy, preventing excessive reaction that could degrade the rubber core. A reaction time of 1.8-2.3 hours results in a high grafting rate, ensuring uniform distribution of the toughening phase. Grinding breaks up filler agglomerates, resulting in more uniform dispersion of the nanofillers. A temperature ≤60℃ inhibits the early reaction between the anhydride and epoxy, preventing abrupt changes in resin viscosity. The reactive diluent is added last to prevent premature consumption of the curing agent by its epoxy groups, maximizing dilution efficiency and degassing to reduce porosity.

[0028] In summary, this application has the following beneficial effects:

[0029] 1. This application utilizes the synergistic combination of tetrafunctional phenolic epoxy resin, biphenyl-type epoxy resin, core-shell rubber, and triphenylphosphine to produce a resin with excellent high-temperature resistance and high elongation at break, which can be applied to carbon fiber winding of motor rotors.

[0030] 2. In this application, polyetheretherketone micro powder is preferred, which can suppress the thermal deformation of the overall material and further improve its high-temperature resistance.

[0031] 3. The method of this application can avoid phase separation caused by cold mixing, make the nanofiller more uniformly dispersed, avoid sudden changes in resin viscosity, and reduce porosity. Detailed Implementation

[0032] The present application will be further described in detail below with reference to embodiments and comparative examples.

[0033] Example

[0034] Example 1

[0035] This embodiment provides a resin for carbon fiber winding of motor rotor, comprising the following raw materials: 50 kg of tetrafunctional phenolic epoxy resin (AG-80), 30 kg of biphenyl epoxy resin (YX4000), 18 kg of core-shell butadiene rubber (MX-154), 0.15 kg of triphenylphosphine (KT004), 23 kg of methyl hexahydrophthalic anhydride (JST), 0.8 kg of benzyl dimethylamine (CAS No.: 103-83-3, in accordance with national standards), 4 kg of nano silica (Cabot CAB-O-SIL TS620), 1.5 kg of silane coupling agent (KH550), and 6.5 kg of cashew phenol glycidyl ether (710).

[0036] This embodiment also provides a method for preparing a resin used in the winding of carbon fiber in an electric motor rotor, comprising the following steps:

[0037] A tetrafunctional phenolic epoxy resin and a biphenyl-type epoxy resin were mixed and heated to 85°C. Core-shell butadiene rubber was added, and the mixture was stirred evenly under nitrogen protection to obtain a homogeneous premix.

[0038] The homogeneous premix was heated to 120°C, triphenylphosphine was added, the reaction was maintained at this temperature for 2 hours, and then cooled to 60°C to obtain the premixed resin.

[0039] Nano-silica and silane coupling agent were mixed evenly and added to premixed resin. The mixture was then ground evenly using a three-roll mill (gap 20μm) to obtain a resin-filler mixture.

[0040] Methylhexahydrophthalic anhydride was heated to 100°C, benzyl dimethylamine was added, and the mixture was stirred until homogeneous. The mixture was then added to the resin-filler mixture and stirred until homogeneous at ≤60°C. Cashew phenol glycidyl ether was added, and the mixture was stirred until homogeneous and degassed to obtain a resin for use in the winding of carbon fiber for motor rotors.

[0041] Example 2

[0042] The only difference between this embodiment and Embodiment 1 is that the resin used for winding the carbon fiber of the motor rotor includes the following raw materials: 40 kg of tetrafunctional phenolic epoxy resin (AG-80), 40 kg of biphenyl epoxy resin (YX4000), 15 kg of core-shell butadiene rubber (MX-154), 0.1 kg of triphenylphosphine (KT004), 20 kg of methyl hexahydrophthalic anhydride (JST), 0.5 kg of benzyl dimethylamine (CAS No.: 103-83-3, in accordance with national standards), 3 kg of nano silica (Cabot CAB-O-SIL TS620), 1 kg of silane coupling agent (KH550), and 5 kg of cashew phenol glycidyl ether (710).

[0043] Example 3

[0044] The only difference between this embodiment and Embodiment 1 is that the resin used for winding the carbon fiber of the motor rotor includes the following raw materials: 60 kg of tetrafunctional phenolic epoxy resin (AG-80), 20 kg of biphenyl epoxy resin (YX4000), 20 kg of core-shell butadiene rubber (MX-154), 0.2 kg of triphenylphosphine (KT004), 25 kg of methyl hexahydrophthalic anhydride (JST), 1 kg of benzyl dimethylamine (CAS No.: 103-83-3, in accordance with national standards), 5 kg of nano silica (Cabot CAB-O-SIL TS620), 2 kg of silane coupling agent (KH550), and 8 kg of cashew phenol glycidyl ether (710).

[0045] Example 4

[0046] The only difference between this embodiment and Embodiment 1 is that an equal amount of core-shell silicone rubber (MX-962) is used to replace the core-shell butadiene rubber (MX-154).

[0047] Example 5

[0048] The only difference between this embodiment and Example 1 is that an equal amount of diaminodiphenyl sulfone (CAS: 80-08-0-003) is used to replace methylhexahydrophthalic anhydride (JST).

[0049] Example 6

[0050] The only difference between this embodiment and Example 1 is that methylhexahydrophthalic anhydride (JST) is replaced with an equal amount of curing agent. The curing agent includes methylhexahydrophthalic anhydride (JST) and diaminodiphenyl sulfone (CAS: 80-08-0-003) in a weight ratio of 3:1.

[0051] Example 7

[0052] The only difference between this embodiment and Example 1 is that methylhexahydrophthalic anhydride (JST) is replaced with an equal amount of curing agent. The curing agent includes methylhexahydrophthalic anhydride (JST) and diaminodiphenyl sulfone (CAS: 80-08-0-003) in a weight ratio of 3.5:1.

[0053] Example 8

[0054] The only difference between this embodiment and Example 1 is that methylhexahydrophthalic anhydride (JST) is replaced with an equal amount of curing agent. The curing agent includes methylhexahydrophthalic anhydride (JST) and diaminodiphenyl sulfone (CAS: 80-08-0-003) in a weight ratio of 4:1.

[0055] Example 9

[0056] The only difference between this embodiment and Example 1 is that methylhexahydrophthalic anhydride (JST) is replaced with an equal amount of curing agent. The curing agent includes methylhexahydrophthalic anhydride (JST) and diaminodiphenyl sulfone (CAS: 80-08-0-003) in a weight ratio of 4.5:1.

[0057] Example 10

[0058] The only difference between this embodiment and Embodiment 1 is that methylhexahydrophthalic anhydride (JST) is replaced with an equal amount of curing agent. The curing agent includes methylhexahydrophthalic anhydride (JST) and diaminodiphenyl sulfone (CAS: 80-08-0-003) in a weight ratio of 5:1.

[0059] Example 11

[0060] The only difference between this embodiment and Example 1 is that benzyldimethylamine (CAS No.: 103-83-3, national standard) is replaced with an equal amount of 2-ethyl-4-methylimidazolium (CAS No. 931-36-2, Smcg).

[0061] Example 12

[0062] The only difference between this embodiment and Embodiment 1 is that an equal amount of carbon nanotubes (brand name ER2253F) are used to replace nano-silica (Cabot CAB-O-SIL TS620).

[0063] Example 13

[0064] The only difference between this embodiment and Embodiment 1 is that the resin used for carbon fiber winding of the motor rotor includes the following raw materials: 50 kg of tetrafunctional phenolic epoxy resin (AG-80), 30 kg of biphenyl epoxy resin (YX4000), 18 kg of core-shell butadiene rubber (MX-154), 0.15 kg of triphenylphosphine (KT004), 23 kg of methyl hexahydrophthalic anhydride (JST), 0.8 kg of benzyl dimethylamine (CAS No.: 103-83-3, in accordance with national standards), 4 kg of nano silica (Cabot CAB-O-SIL TS620), 1.5 kg of silane coupling agent (KH550), 6.5 kg of cashew phenol glycidyl ether (710), and 7 kg of polyether ether ketone micro powder (701).

[0065] In the preparation method of the resin used for carbon fiber winding of motor rotor: methyl hexahydrophthalic anhydride is heated to 100°C, benzyl dimethylamine is added and stirred until uniform, then added to the resin-filler mixture and stirred until uniform at ≤60°C. Polyether ether ketone micro powder and cashew phenol glycidyl ether are mixed and added to the mixture, mixed uniformly, and degassed to obtain the resin used for carbon fiber winding of motor rotor.

[0066] Example 14

[0067] The only difference between this embodiment and Embodiment 1 is that the resin used for carbon fiber winding of the motor rotor includes the following raw materials: 50 kg of tetrafunctional phenolic epoxy resin (AG-80), 30 kg of biphenyl epoxy resin (YX4000), 18 kg of core-shell butadiene rubber (MX-154), 0.15 kg of triphenylphosphine (KT004), 23 kg of curing agent, 0.8 kg of benzyl dimethylamine (CAS No.: 103-83-3, in accordance with national standards), 4 kg of nano silica (Cabot CAB-O-SIL TS620), 1.5 kg of silane coupling agent (KH550), 6.5 kg of cashew phenol glycidyl ether (710), and 7 kg of polyether ether ketone micro powder (701). The curing agent includes methyl hexahydrophthalic anhydride (JST) and diaminodiphenyl sulfone (CAS: 80-08-0-003) in a weight ratio of 4:1.

[0068] The method for preparing the resin used in carbon fiber winding of motor rotors comprises the following steps:

[0069] A tetrafunctional phenolic epoxy resin and a biphenyl-type epoxy resin were mixed and heated to 85°C. Core-shell butadiene rubber was added, and the mixture was stirred evenly under nitrogen protection to obtain a homogeneous premix.

[0070] The homogeneous premix was heated to 120°C, triphenylphosphine was added, the reaction was maintained at this temperature for 2 hours, and then cooled to 60°C to obtain the premixed resin.

[0071] Nano-silica and silane coupling agent were mixed evenly and added to premixed resin. The mixture was then ground evenly using a three-roll mill (gap 20μm) to obtain a resin-filler mixture.

[0072] Methylhexahydrophthalic anhydride and diaminodiphenyl sulfone were mixed in proportion, heated to 100°C, benzyl dimethylamine was added, and stirred until uniform. The mixture was then added to the resin-filler mixture and stirred until uniform at ≤60°C. Polyether ether ketone micro powder and cashew phenol glycidyl ether were mixed and added to the mixture. The mixture was stirred until uniform and degassed to obtain a resin for use in carbon fiber winding of motor rotors.

[0073] Example 15

[0074] The only difference between this embodiment and Embodiment 1 is that the method for preparing the resin used for winding carbon fiber in motor rotors adopts the following steps:

[0075] A tetrafunctional phenolic epoxy resin and a biphenyl epoxy resin were mixed and heated to 80°C. Core-shell butadiene rubber was added, and the mixture was kept warm and stirred until homogeneous under nitrogen protection to obtain a homogeneous premix.

[0076] The homogeneous premix was heated to 115°C, triphenylphosphine was added, and the reaction was maintained at this temperature for 2.3 hours. The mixture was then cooled to 60°C to obtain the premixed resin.

[0077] Nano-silica and silane coupling agent were mixed evenly and added to premixed resin. The mixture was then ground evenly using a three-roll mill (gap 20μm) to obtain a resin-filler mixture.

[0078] Methylhexahydrophthalic anhydride was heated to 100°C, benzyl dimethylamine was added, and the mixture was stirred until homogeneous. The mixture was then added to the resin-filler mixture and stirred until homogeneous at ≤60°C. Cashew phenol glycidyl ether was added, and the mixture was stirred until homogeneous and degassed to obtain a resin for use in the winding of carbon fiber for motor rotors.

[0079] Example 16

[0080] The only difference between this embodiment and Embodiment 1 is that the method for preparing the resin used for winding carbon fiber in motor rotors adopts the following steps:

[0081] A mixture of tetrafunctional phenolic epoxy resin and biphenyl epoxy resin was heated to 90°C, and core-shell butadiene rubber was added. The mixture was kept warm and stirred until homogeneous under nitrogen protection to obtain a homogeneous premix.

[0082] The homogeneous premix was heated to 125°C, triphenylphosphine was added, and the reaction was maintained at this temperature for 1.8 hours. The mixture was then cooled to 50°C to obtain the premixed resin.

[0083] Nano-silica and silane coupling agent were mixed evenly and added to premixed resin. The mixture was then ground evenly using a three-roll mill (gap 20μm) to obtain a resin-filler mixture.

[0084] Methylhexahydrophthalic anhydride was heated to 100°C, benzyl dimethylamine was added, and the mixture was stirred until homogeneous. The mixture was then added to the resin-filler mixture and stirred until homogeneous at ≤60°C. Cashew phenol glycidyl ether was added, and the mixture was stirred until homogeneous and degassed to obtain a resin for use in the winding of carbon fiber for motor rotors.

[0085] Comparative Example

[0086] Comparative Example 1

[0087] The only difference between this comparative example and Example 1 is that an equal amount of tetrafunctional phenolic epoxy resin (AG-80) is used instead of biphenyl epoxy resin (YX4000).

[0088] Comparative Example 2

[0089] The only difference between this comparative example and Example 1 is that an equal amount of biphenyl-type epoxy resin (YX4000) was used to replace the tetrafunctional phenolic epoxy resin (AG-80).

[0090] Comparative Example 3

[0091] The only difference between this comparative example and Example 1 is that an equal amount of tetrafunctional phenolic epoxy resin (AG-80) is used to replace the core-shell butadiene rubber (MX-154).

[0092] Comparative Example 4

[0093] The only difference between this comparative example and Example 1 is that triphenylphosphine (KT004) is replaced with an equal amount of tetrafunctional phenolic epoxy resin (AG-80).

[0094] Performance testing

[0095] The following performance tests were conducted on Examples 1-16 and Comparative Examples 1-4:

[0096] According to ASTM D7028, the glass transition temperature (Tg) of the resins used for carbon fiber winding of motor rotors in each example and comparative example was tested, and the test results are shown in Table 1.

[0097] According to ASTM D638, the elongation at break of the resin used for carbon fiber winding of motor rotors in each example and comparative example was tested, and the test results are shown in Table 1.

[0098] Table 1

[0099] Group | Tg / ℃ | Elongation at Break / % | Example 1 | 192 | 3.7 | Example 2 | 188 | 3.6 | Example 3 | 186 | 3.3 | Example 4 | 193 | 3.9 | Example 5 | 194 | 3.6 | Example 6 | 194 | 3.7 | Example 7 | 196 | 3.9 | Example 8 | 197 | 4.0 | Example 9 | 197 | 3.9 | Example 10 | 199 | 3.6 | Example 11 | 196 | 3.6 | Example 12 | 187 | 3.9 | Example 13 | 196 | 4.0 | Example 14 | 198 | 4.3 | Example 15 | 192 | 3.6 | Example 16 | 193 | 3.8 | Comparative Example 1 | 168 | 1.8 | Comparative Example 2 | 171 | 1.7 | Comparative Example 3 | 163 | 1.4 | Comparative Example 4 | 174 | 2.0 surface

[0100] As can be seen from Example 1 and Comparative Examples 1-4, and in conjunction with Table 1, compared to Example 1, the glass transition temperature (Tg) and elongation at break of Comparative Examples 1-4 are significantly lower. This indicates that the preparation method of Example 1 helps to improve the glass transition temperature (Tg) and elongation at break of the resin. Furthermore, the absence of any one of the four functional group phenolic epoxy resins, biphenyl-type epoxy resins, core-shell rubbers, or triphenylphosphine will lead to a decrease in the glass transition temperature (Tg) and elongation at break of the resin.

[0101] As can be seen from Examples 1-5 and Table 1, the glass transition temperature (Tg) of Examples 1-5 is greater than 180°C, and the elongation at break is greater than 2%. This indicates that the preparation methods within the range of Examples 1-5 all contribute to improving the glass transition temperature (Tg) and elongation at break of the resin.

[0102] Compared to Example 1, the glass transition temperature (Tg) of Examples 6-10 was increased, and the elongation at break of Examples 7-9 was increased, but the elongation at break of Examples 6 and 10 was not increased. This indicates that using a curing agent composed of methylhexahydrophthalic anhydride and diaminodiphenyl sulfone helps to increase the glass transition temperature (Tg) of the resin. Moreover, using methylhexahydrophthalic anhydride and diaminodiphenyl sulfone in a weight ratio of (3.5-4.5):1 helps to simultaneously increase the elongation at break of the resin.

[0103] Compared to Example 1, the glass transition temperature (Tg) of Examples 11-16 is also greater than 180°C, and the elongation at break is greater than 2%. This indicates that by using the raw material ratios and process conditions of Examples 11-16, the glass transition temperature (Tg) and elongation at break of the resin can also be improved.

[0104] This specific embodiment is merely an explanation of this application and is not intended to limit it. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they fall within the scope of the claims of this application.

Claims

1. A resin used for carbon fiber winding in motor rotors, characterized in that, The raw materials include the following parts by weight: 40-60 parts tetrafunctional phenolic epoxy resin, 20-40 parts biphenyl epoxy resin, 15-20 parts core-shell rubber, 0.1-0.2 parts triphenylphosphine, 20-25 parts curing agent, 0.5-1 part accelerator, 3-5 parts nanofiller, 1-2 parts silane coupling agent, and 5-8 parts reactive diluent; the core-shell rubber is core-shell butadiene rubber or core-shell silicone rubber; the curing agent includes methyl hexahydrophthalic anhydride and diaminodiphenyl sulfone in a weight ratio of (3.5-4.5):1; the nanofiller is nano-silica or carbon nanotubes; the core-shell silicone rubber is MX-962, and the core-shell butadiene rubber is MX-154.

2. The resin used for carbon fiber winding of an electric motor rotor according to claim 1, characterized in that, The accelerator is benzyldimethylamine or 2-ethyl-4-methylimidazole.

3. The resin used for carbon fiber winding of an electric motor rotor according to claim 1, characterized in that, The active diluent is cashew phenol glycidyl ether.

4. The resin used for carbon fiber winding of an electric motor rotor according to claim 1, characterized in that, It also includes polyetheretherketone (PEEK) micro powder.

5. A method for preparing a resin for carbon fiber winding of an electric motor rotor according to any one of claims 1-4, characterized in that, The process includes the following steps: mixing tetrafunctional phenolic epoxy resin and biphenyl epoxy resin, heating to 80-90℃, adding core-shell rubber, and stirring evenly under nitrogen protection to obtain a homogeneous premix; heating the homogeneous premix to 115-125℃, adding triphenylphosphine, reacting at this temperature for 1.8-2.3 hours, and cooling to 50-60℃ to obtain a premixed resin; mixing nanofiller and silane coupling agent evenly, adding to the premixed resin, and grinding until homogeneous to obtain a resin-filler mixture; mixing curing agent and accelerator evenly, adding to the resin-filler mixture, stirring evenly at ≤60℃, adding reactive diluent, mixing evenly, and degassing to obtain a resin for use in carbon fiber winding of motor rotors.