Method for curing epoxy resin

Abstract

The invention discloses a curing method of epoxy resin. The method comprises the following steps: mixing an imidazole curing agent with epoxy resin, adding a magnetic filler dispersion liquid and a heat conduction enhancer, uniformly heating, and applying a constant magnetic field and then applying an alternating magnetic field in the heating process. According to the method, an imidazole curing agent and a magnetic filler are added into epoxy resin, so that a traditional epoxy resin curing system is endowed with the characteristic of magnetic response. According to the method, in the curing process, a constant magnetic field and an alternating magnetic field are sequentially applied, disturbance of magnetic filler to a peripheral curing agent temperature field is achieved in a non-contact mode of the applied magnetic field and through local mechanical motion of magnetic particles in an external field, heat distribution in the curing stage is uniform, and then the curing effect is improved.

Description

Technical Field

[0001] This invention belongs to the field of polymer materials technology, and specifically relates to a curing method for epoxy resin. Background Technology

[0002] As microelectronic devices become increasingly integrated and miniaturized, the performance requirements for curing agents in packaging materials are becoming more and more stringent. Traditional curing agents (such as epoxy resin systems) are no longer sufficient to meet the needs of scenarios such as 5G chips and advanced packaging (Fan-Out, 3D IC).

[0003] Traditional thermosetting materials (such as epoxy anhydride systems) face challenges: devices such as 5G RF modules require the development of new functional curing agents and supporting curing process devices to achieve full control over the curing process, completing curing from below 120℃ to avoid high-frequency dielectric loss; gradient crosslinking requirements: the curing shrinkage rate difference of multilayer dielectric materials in Fan-Out packaging needs to be controlled within 0.3%; chip mounting processes require curing start time (T0) fluctuation ≤ 2 seconds and temperature sensitivity of ±1℃ / min.

[0004] Therefore, new curing agents need to have the following characteristics: low-temperature rapid curing (80~150℃) to avoid thermal stress damage to sensitive components; gradient curing ability to ensure uniform cross-linking of materials from the surface to the interior; and time-temperature synergistic controllability to adapt to the rhythm of multi-process production.

[0005] Although existing technologies have significantly improved the curing performance of traditional curing agents, the heat transfer mechanism during curing and experimental data both indicate that significant temperature differences in different parts persist throughout the curing and service life process. Curing agent development needs to overcome the challenge of three-dimensional coordinated control of heat, time, and space. The core contradiction in the curing process lies in the conflict between the demand for high precision and the material's response hysteresis.

[0006] Future breakthroughs include: developing smart curing agents (such as temperature-sensitive latent catalysts); introducing AI-powered real-time monitoring systems to dynamically adjust curing parameters; and optimizing curing kinetics through molecular design (such as lowering activation energy). Only by shifting from "experience-driven" to "data-driven" approaches can we meet the manufacturing needs of next-generation microelectronics and new materials.

[0007] Improving the curing process to make its parameters adjustable and measurable, in order to meet the development needs of industries such as new materials and microelectronics, has become a problem that needs to be solved. Summary of the Invention

[0008] The first objective of this invention is to provide a curing method for epoxy resin with high precision and low curing response hysteresis.

[0009] A second object of the present invention is to provide a polymer prepared by the method described above.

[0010] A third object of the present invention is to provide an application of a polymer prepared by the said method.

[0011] The present invention is achieved through the following technical solution: a curing method for epoxy resin, comprising mixing an imidazole curing agent with epoxy resin, adding a magnetic filler dispersion and a thermally conductive enhancer, then heating uniformly, and applying a constant magnetic field first and then an alternating magnetic field during the heating process.

[0012] Furthermore, the imidazole curing agent includes 1-methylimidazolium or The epoxy resin includes bisphenol A type epoxy resin; the magnetic filler dispersion includes magnetic filler, dispersant and ethanol; the magnetic filler includes iron oxide nanoparticles or cobalt oxide nanoparticles; the magnetic filler dispersion includes dispersant; the dispersant includes polyethylene glycol; the thermal conductivity enhancer includes modified short-cut carbon fibers.

[0013] Furthermore, the particle size of the iron oxide nanoparticles is 50nm-200nm; the particle size of the cobalt oxide nanoparticles is 80-300nm; the diameter of the modified short-cut carbon fiber is 7μm and the length is 100μm; and the polyethylene glycol includes PEG-4000.

[0014] Furthermore, the weight ratio of the epoxy resin to the imidazole curing agent is 87-100:3; the weight ratio of the epoxy resin to the magnetic filler is 87-100:20-23; the weight ratio of the epoxy resin to the thermal conductivity enhancer is 87-100:15; and the weight ratio of the epoxy resin to the dispersant is 87-100:2.

[0015] Furthermore, the preparation method of the modified chopped carbon fiber includes the following steps: after the chopped carbon fiber is oxidized by concentrated nitric acid, it is surface modified with silane coupling agent KH-550 to obtain the modified carbon fiber.

[0016] Furthermore, the uniform heating includes the steps of heating to 60°C at a rate of 3°C / min under a constant magnetic field, then heating to 90°C at a rate of 1°C / min; and then heating to 100°C at a rate of 1°C / min under an alternating magnetic field.

[0017] Furthermore, the strength of the constant magnetic field is 0.5T; the strength of the alternating magnetic field is 0.5T.

[0018] The polymer obtained by the curing method of the epoxy resin is described above.

[0019] The polymer is used in the preparation of electromagnetic shielding materials or in the preparation of motor insulation and encapsulation materials.

[0020] Compared to existing technologies, the advantages of this invention are as follows: The curing method of this invention, by first applying a constant magnetic field during uniform heating to liquefy the curing system, causes the magnetic superfiller to oriented and uniformly arrange itself within the curing system. Then, during the curing process, an alternating magnetic field is applied. At this time, the magnetic filler inside the curing system responds to the applied magnetic field. The magnetic filler then undergoes mechanical movement within the alternating magnetic field, thereby disturbing the temperature field of the curing system, promoting heat dispersion and conduction within the curing system, and thus improving the curing efficiency of the curing agent and the performance of the cured product.

[0021] Compared with epoxy curing methods, the thermal parameters of the curing method provided by this invention have all been changed to some extent. Due to the introduction of thermal conductivity enhancers, the thermal conductivity of the epoxy resin curing system is significantly improved by this method. Therefore, as the thermal conductivity increases, the curing time of this curing system at 100°C gradually shortens. Detailed Implementation

[0022] This embodiment provides a method for curing epoxy resin. The method involves mixing an imidazole curing agent with epoxy resin, adding a magnetic filler dispersion and a thermal conductivity enhancer, then uniformly heating and applying a magnetic field to achieve uniform curing of the epoxy resin. This method solves the problems of limited controllable curing temperature range, few controllable factors in the curing process, and lack of directional adjustment in the curing process inherent in traditional curing methods. This is because the addition of magnetic filler endows the curing system with the magnetic response characteristics of the curing agent. During the curing process, the magnetic field can be introduced to achieve an external field response of the magnetic filler. Through the localized mechanical movement of magnetic particles under the applied magnetic field, the temperature field of the surrounding curing system is disturbed, thereby further controlling the heat distribution during the curing stage and improving the curing effect.

[0023] Preferably, the curing agent may be 1-methylimidazole or It can also be other types of imidazole derivatives with lone pairs of electrons on the imidazole ring. The epoxy resin includes bisphenol A type epoxy resin; those skilled in the art will understand that the epoxy resin can also be other types of epoxy resin. The magnetic filler dispersion includes magnetic filler, dispersant and ethanol. The magnetic filler is iron(III) oxide nanoparticles or cobalt(III) oxide nanoparticles; those skilled in the art will understand that the magnetic filler can also be other magnetic nanomaterials. The thermal conductive agent is modified short-cut carbon fiber; those skilled in the art will understand that the thermal conductive agent can also be other high thermal conductivity carbon materials, such as graphene. The dispersant includes polyethylene glycol.

[0024] Preferably, the particle size of the iron oxide nanoparticles is 50nm-200nm; the particle size of the cobalt oxide nanoparticles is 80-300nm; the diameter of the modified short-cut carbon fiber is 7μm and the length is 100μm; and the polyethylene glycol includes PEG-4000.

[0025] Preferably, the weight ratio of epoxy resin to curing agent is 87-100:3; the weight ratio of epoxy resin to magnetic filler is 87-100:20-23; the weight ratio of epoxy resin to thermal conductivity enhancer is 87-100:15; and the weight ratio of epoxy resin to dispersant is 87-100:2.

[0026] Preferably, the method for preparing the modified chopped carbon fiber includes the following steps: after oxidizing the chopped carbon fiber with concentrated nitric acid, the surface is modified with silane coupling agent KH-550 to obtain the modified carbon fiber.

[0027] Preferably, the uniform heating includes the steps of heating to 60°C at a rate of 3°C / min under a constant magnetic field, then heating to 90°C at a rate of 1°C / min; and then heating to 100°C at a rate of 1°C / min under an alternating magnetic field.

[0028] Preferably, the strength of the constant magnetic field is 0.5T; the strength of the alternating magnetic field is 0.5T.

[0029] The present invention also provides a polymer prepared by the curing method of the epoxy resin described above.

[0030] The present invention also provides applications of the polymer. The polymer can be used to prepare electromagnetic shielding materials; or to prepare electrical insulation encapsulation materials.

[0031] The present invention will be further described below with reference to specific embodiments.

[0032] Example 1 is as follows: Resin: Bisphenol A type epoxy resin (E-51) 87g.

[0033] Curing agent: 1-methylimidazole (1-MI) (product of Haodeng (Shanghai) Chemical Technology Co., Ltd.) 3g; Magnetic filler: iron oxide nanoparticles (particle size 50nm) 20g; Thermal conductivity enhancer: short-cut carbon fiber (diameter 7μm, length 100μm) 15g; Dispersant: polyethylene glycol (PEG-4000) 2g.

[0034] Preparation process of magnetic filler dispersion: Add ferric oxide magnetic particles and polyethylene glycol to anhydrous ethanol (50 ml), and ultrasonically disperse for 45 min (power 300 W) to obtain magnetic filler dispersion.

[0035] Preparation method of modified short-cut carbon fiber: After carbon fiber is oxidized by concentrated nitric acid, it is surface modified with silane coupling agent KH-550.

[0036] Curing process: Bisphenol A type epoxy resin, 1-methylimidazole and magnetic filler dispersion, modified short-cut carbon fiber are mixed and the curing system is uniformly heated to 60°C at a rate of 3°C / min under a constant magnetic field of 0.5T and stirred, and then heated to 90°C at a rate of 1°C / min; then heated to 100°C at a rate of 1°C / min under an alternating magnetic field.

[0037] In this embodiment, the curing time was recorded as 9.5 min, and the thermal conductivity of the obtained polymer was 0.24 W / (m·K).

[0038] Example 2 is as follows:

[0039] Resin: 90g of bisphenol A type epoxy resin (E-51); Curing agent: 3g of 1-methylimidazole (1-MI) (Holden (Shanghai) Chemical Technology Co., Ltd.); Magnetic filler: 20g of iron oxide nanoparticles (particle size 100nm); Thermal conductivity enhancer: 15g of short-cut carbon fiber (diameter 7μm, length 100μm); Dispersant: 2g of polyethylene glycol (PEG-4000).

[0040] Preparation process of magnetic filler dispersion: Add ferric oxide magnetic particles and polyethylene glycol to anhydrous ethanol (50 ml), and ultrasonically disperse for 45 min (power 300 W) to obtain magnetic filler dispersion.

[0041] Preparation method of modified short-cut carbon fiber: After carbon fiber is oxidized by concentrated nitric acid, it is surface modified with silane coupling agent KH-550.

[0042] Bisphenol A type epoxy resin, 1-methylimidazole and magnetic filler dispersion, and modified short-cut carbon fiber were mixed. The curing system was uniformly heated to 60°C under stirring at a rate of 3°C / min under a constant magnetic field of 0.5T, and then heated to 90°C at a rate of 1°C / min. Finally, it was heated to 100°C under an alternating magnetic field at a rate of 1°C / min.

[0043] In this embodiment, the curing time was recorded as 9.6 min, and the thermal conductivity of the obtained polymer was 0.25 W / (m·K).

[0044] Example 3 is as follows:

[0045] Resin: 95g of bisphenol A type epoxy resin (E-51); Curing agent: 3g of 1-methylimidazole (1-MI) (Holden (Shanghai) Chemical Technology Co., Ltd.); Magnetic filler: 20g of iron oxide nanoparticles (particle size 150nm); Thermal conductivity enhancer: 15g of short-cut carbon fiber (diameter 7μm, length 100μm); Dispersant: 2g of polyethylene glycol (PEG-4000).

[0046] Preparation process of magnetic filler dispersion: Add ferric oxide magnetic particles and polyethylene glycol to anhydrous ethanol (50 ml), and ultrasonically disperse for 45 min (power 300 W) to obtain magnetic filler dispersion.

[0047] Preparation method of modified short-cut carbon fiber: After carbon fiber is oxidized by concentrated nitric acid, it is surface modified with silane coupling agent KH-550.

[0048] Curing process: Bisphenol A type epoxy resin, 1-methylimidazole and magnetic filler dispersion, modified short-cut carbon fiber are mixed and the curing system is uniformly heated to 60°C at a rate of 3°C / min under a constant magnetic field of 0.5T and stirred, and then heated to 90°C at a rate of 1°C / min; then heated to 100°C at a rate of 1°C / min under an alternating magnetic field.

[0049] In this embodiment, the curing time was recorded as 9.4 min, and the thermal conductivity of the obtained polymer was 0.25 W / (m·K).

[0050] Example 4 is as follows:

[0051] Resin: 100g of bisphenol A type epoxy resin (E-51); Curing agent: 3g of 1-methylimidazole (1-MI) (Holden (Shanghai) Chemical Technology Co., Ltd.); Magnetic filler: 20g of iron oxide nanoparticles (particle size 200nm); Thermal conductivity enhancer: 15g of short-cut carbon fiber (diameter 7μm, length 100μm); Dispersant: 2g of polyethylene glycol (PEG-4000).

[0052] Preparation process of magnetic filler dispersion: Add ferric oxide magnetic particles and polyethylene glycol to anhydrous ethanol (50 ml), and ultrasonically disperse for 45 min (power 300 W) to obtain magnetic filler dispersion.

[0053] Preparation method of modified short-cut carbon fiber: After carbon fiber is oxidized by concentrated nitric acid, it is surface modified with silane coupling agent KH-550.

[0054] Curing process: Bisphenol A type epoxy resin, 1-methylimidazole and magnetic filler dispersion, modified short-cut carbon fiber are mixed and the curing system is uniformly heated to 60°C at a rate of 3°C / min under a constant magnetic field of 0.5T and stirred, and then heated to 90°C at a rate of 1°C / min; then heated to 100°C at a rate of 1°C / min under an alternating magnetic field.

[0055] In this embodiment, the curing time was recorded as 9.2 min, and the thermal conductivity of the obtained polymer was 0.26 W / (m·K).

[0056] Example 5 is as follows:

[0057] Resin: 87g of bisphenol A type epoxy resin (E-51); Curing agent: 3g of 1-methylimidazole (1-MI) (Holden (Shanghai) Chemical Technology Co., Ltd.); Magnetic filler: 23g of cobalt oxide (80nm); Thermal conductivity enhancer: 15g of short-cut carbon fiber (7μm in diameter and 100μm in length); Dispersant: 2g of polyethylene glycol (PEG-4000).

[0058] Preparation process of magnetic filler dispersion: Cobalt oxide magnetic particles and polyethylene glycol are added to anhydrous ethanol (50 ml) and ultrasonically dispersed for 45 min (power 300 W) to obtain magnetic filler dispersion.

[0059] Preparation method of modified short-cut carbon fiber: After carbon fiber is oxidized by concentrated nitric acid, it is surface modified with silane coupling agent KH-550.

[0060] Curing process: Bisphenol A type epoxy resin, 1-methylimidazole and magnetic filler dispersion, modified short-cut carbon fiber are mixed and the curing system is uniformly heated to 60°C at a rate of 3°C / min under a constant magnetic field of 0.5T and stirred, and then heated to 90°C at a rate of 1°C / min; then heated to 100°C at a rate of 1°C / min under an alternating magnetic field.

[0061] In this embodiment, the curing time was recorded as 9.8 min, and the thermal conductivity of the obtained polymer was 0.23 W / (m·K).

[0062] Example 6 is as follows:

[0063] Resin: 90g of bisphenol A type epoxy resin (E-51); Curing agent: 3g of 1-methylimidazole (1-MI) (Holden (Shanghai) Chemical Technology Co., Ltd.); Magnetic filler: 23g of cobalt oxide (100nm); Thermal conductivity enhancer: 15g of short-cut carbon fiber (7μm in diameter and 100μm in length); Dispersant: 2g of polyethylene glycol (PEG-4000).

[0064] Preparation process of magnetic filler dispersion: Cobalt oxide particles and polyethylene glycol are added to anhydrous ethanol (50 ml) and ultrasonically dispersed for 45 min (power 300 W) to obtain magnetic filler dispersion.

[0065] Preparation method of modified short-cut carbon fiber: After carbon fiber is oxidized by concentrated nitric acid, it is surface modified with silane coupling agent KH-550.

[0066] Curing process: Bisphenol A type epoxy resin, 1-methylimidazole and magnetic filler dispersion, modified short-cut carbon fiber are mixed and the curing system is uniformly heated to 60°C at a rate of 3°C / min under a constant magnetic field of 0.5T and stirred, and then heated to 90°C at a rate of 1°C / min; then heated to 100°C at a rate of 1°C / min under an alternating magnetic field.

[0067] In this embodiment, the curing time was recorded as 9.5 min, and the thermal conductivity of the obtained polymer was 0.24 W / (m·K).

[0068] Example 7 is as follows:

[0069] Resin: 95g of bisphenol A type epoxy resin (E-51); Curing agent: 3g of 1-methylimidazole (1-MI) (Holden (Shanghai) Chemical Technology Co., Ltd.); Magnetic filler: 23g of cobalt oxide (200nm); Thermal conductivity enhancer: 15g of short-cut carbon fiber (7μm in diameter and 100μm in length); Dispersant: 2g of polyethylene glycol (PEG-4000).

[0070] Preparation process of magnetic filler dispersion: Cobalt oxide particles and polyethylene glycol are added to anhydrous ethanol (50 ml) and ultrasonically dispersed for 45 min (power 300 W) to obtain magnetic filler dispersion.

[0071] Preparation method of modified short-cut carbon fiber: After carbon fiber is oxidized by concentrated nitric acid, it is surface modified with silane coupling agent KH-550.

[0072] Curing process: Bisphenol A type epoxy resin, 1-methylimidazole and magnetic filler dispersion, modified short carbon fiber are mixed and the curing system is uniformly heated to 60℃ at a rate of 3℃ / min under a constant magnetic field of 0.5T and stirred, and then heated to 90℃ at a rate of 1℃ / min; then heated to 100℃ at a rate of 1℃ / min under an alternating magnetic field.

[0073] In this embodiment, the curing time was recorded as 9.6 min, and the thermal conductivity of the obtained polymer was 0.24 W / (m·K).

[0074] Example 8 is as follows:

[0075] Resin: 100g of bisphenol A type epoxy resin (E-51), curing agent: 3g of 1-methylimidazole (1-MI) (Holden (Shanghai) Chemical Technology Co., Ltd.), magnetic filler: 23g of cobalt oxide (250nm); thermal conductivity enhancer: 15g of short-cut carbon fiber (7μm in diameter and 100μm in length), dispersant: 2g of polyethylene glycol (PEG-4000).

[0076] Preparation process of magnetic filler dispersion: Cobalt oxide particles and polyethylene glycol are added to anhydrous ethanol (50 ml) and ultrasonically dispersed for 45 min (power 300 W) to obtain magnetic filler dispersion.

[0077] Preparation method of modified short-cut carbon fiber: After carbon fiber is oxidized by concentrated nitric acid, it is surface modified with silane coupling agent KH-550.

[0078] Curing process: Bisphenol A type epoxy resin, 1-methylimidazole and magnetic filler dispersion, modified short-cut carbon fiber are mixed and the curing system is uniformly heated to 60°C at a rate of 3°C / min under a constant magnetic field of 0.5T and stirred, and then heated to 90°C at a rate of 1°C / min; then heated to 100°C at a rate of 1°C / min under an alternating magnetic field.

[0079] In this embodiment, the curing time was recorded as 9.2 min, and the thermal conductivity of the obtained polymer was 0.23 W / (m·K).

[0080] Example 9 is as follows:

[0081] Resin: 100g of bisphenol A type epoxy resin (E-51), curing agent: 3g of 1-methylimidazole (1-MI) (Holden (Shanghai) Chemical Technology Co., Ltd.), magnetic filler: 23g of cobalt oxide (300nm); thermal conductivity enhancer: 15g of short-cut carbon fiber (7μm in diameter and 100μm in length), dispersant: 2g of polyethylene glycol (PEG-4000).

[0082] Preparation process of magnetic filler dispersion: Cobalt oxide particles and polyethylene glycol are added to anhydrous ethanol (50 ml) and ultrasonically dispersed for 45 min (power 300 W) to obtain magnetic filler dispersion.

[0083] Preparation method of modified short-cut carbon fiber: After carbon fiber is oxidized by concentrated nitric acid, it is surface modified with silane coupling agent KH-550.

[0084] Curing process: Bisphenol A type epoxy resin, 1-methylimidazole and magnetic filler dispersion, modified short carbon fiber are mixed and the curing system is uniformly heated to 60℃ at a rate of 3℃ / min under a constant magnetic field of 0.5T and stirred, and then heated to 90℃ at a rate of 1℃ / min; then heated to 100℃ at a rate of 1℃ / min under an alternating magnetic field.

[0085] In this embodiment, the curing time was recorded as 9.7 min, and the thermal conductivity of the obtained polymer was 0.26 W / (m·K).

[0086] Comparative Example 1 is as follows: Resin: 100g of bisphenol A type epoxy resin (E-51); Curing agent: 3g of 1-methylimidazole (1-MI) (Holden (Shanghai) Chemical Technology Co., Ltd.); Thermal conductivity enhancer: 15g of short-cut carbon fiber (7μm in diameter and 100μm in length); Dispersant: 2g of polyethylene glycol (PEG-4000).

[0087] Preparation method of modified short-cut carbon fiber: After carbon fiber is oxidized by concentrated nitric acid, it is surface modified with silane coupling agent KH-550.

[0088] Curing procedure: Mix bisphenol A type epoxy resin, 1-methylimidazole and modified short-cut carbon fiber, and heat the curing system uniformly to 60°C under stirring at a rate of 3°C / min, then heat to 90°C at a rate of 1°C / min; then heat to 100°C at a rate of 1°C / min.

[0089] In this embodiment, the curing time was recorded as 13.6 min, and the thermal conductivity of the obtained polymer was 0.20 W / (m·K).

[0090] Comparative Example 2 is as follows: Resin: 100g of bisphenol A type epoxy resin (E-51); curing agent: 3g of 1-methylimidazole (1-MI) (Holden (Shanghai) Chemical Technology Co., Ltd.) (3% of the epoxy resin mass); magnetic filler: 20g of iron oxide nanoparticles (particle size 200nm); dispersant: 2g of polyethylene glycol (PEG-4000).

[0091] Preparation process of magnetic filler dispersion: Add ferric oxide magnetic particles and polyethylene glycol to anhydrous ethanol (50 ml), and ultrasonically disperse for 45 min (power 300 W) to obtain magnetic filler dispersion.

[0092] Curing procedure: Bisphenol A type epoxy resin, 1-methylimidazole, and modified short-cut carbon fiber are mixed and the curing system is uniformly heated to 60°C at a rate of 3°C / min under a constant magnetic field of 0.5T and stirred, and then heated to 90°C at a rate of 1°C / min; then heated to 100°C at a rate of 1°C / min under an alternating magnetic field.

[0093] In this embodiment, the curing time was recorded as 14.3 min, and the thermal conductivity of the obtained polymer was 0.15 W / (m·K).

[0094] Comparative Example 3 is as follows: Resin: 100g of bisphenol A type epoxy resin (E-51); Curing agent: 3g of 1-methylimidazole (1-MI) (Holden (Shanghai) Chemical Technology Co., Ltd.) (3% of the epoxy resin mass); Magnetic filler: 20g of iron oxide nanoparticles (particle size 50nm-200nm); Thermal conductivity enhancer: 15g of short-cut carbon fiber (diameter 7μm, length 100μm).

[0095] Preparation process of magnetic filler dispersion: Add ferric oxide magnetic particles to anhydrous ethanol (50ml) and ultrasonically disperse for 45min (power 300W) to obtain magnetic filler dispersion.

[0096] Preparation method of modified short-cut carbon fiber: After carbon fiber is oxidized by concentrated nitric acid, it is surface modified with silane coupling agent KH-550.

[0097] Curing procedure: Bisphenol A type epoxy resin, 1-methylimidazole, and modified short-cut carbon fiber are mixed and the curing system is uniformly heated to 60°C at a rate of 3°C / min under a constant magnetic field of 0.5T and stirred, and then heated to 90°C at a rate of 1°C / min; then heated to 100°C at a rate of 1°C / min under an alternating magnetic field.

[0098] In this embodiment, the curing time was recorded as 14.1 min, and the thermal conductivity of the obtained polymer was 0.20 W / (m·K).

[0099] Comparative Example 4 is as follows: Resin: Bisphenol A type epoxy resin (E-51) 87-100g; Curing agent: 1-methylimidazole (1-MI) (Holden (Shanghai) Chemical Technology Co., Ltd.) 3g (3% of epoxy resin mass); Magnetic filler: Iron oxide nanoparticles (particle size 50nm-200nm) 20g; Thermal conductivity enhancer: Short-cut carbon fiber (diameter 7μm, length 100μm) 15g; Dispersant: Polyethylene glycol (PEG-4000) 2g.

[0100] Preparation process of magnetic filler dispersion: Add ferric oxide magnetic particles and polyethylene glycol to anhydrous ethanol (50 ml), and ultrasonically disperse for 45 min (power 300 W) to obtain magnetic filler dispersion.

[0101] Curing procedure: Bisphenol A type epoxy resin, 1-methylimidazole and short carbon fiber are mixed and the curing system is uniformly heated to 60°C at a rate of 3°C / min under a constant magnetic field of 0.5T and stirred, and then heated to 90°C at a rate of 1°C / min; then heated to 100°C at a rate of 1°C / min under an alternating magnetic field.

[0102] In this embodiment, the curing time was recorded as 11.6 min, and the thermal conductivity of the obtained polymer was 0.22 W / (m·K).

[0103] The curing method provided by this invention uses an external magnetic field to enable the magnetic particles in the curing system of the magnetic imidazole derivative-based curing agent to respond to the external field during the curing process. This allows for localized mechanical movement of the magnetic particles in the curing system, thereby disturbing the temperature field of the surrounding curing agent and improving the curing efficiency of the magnetic curing agent and the curing performance of the cured product.

[0104] The curing method provided by this invention can generate a relatively uniform temperature field in the curing system, resulting in relatively consistent thermal and chemical shrinkage within the curing agent. This leads to a smaller performance and stress gradient within the product, thus reducing internal thermal and curing shrinkage stress and lowering the probability of warping, bending, matrix cracking, and delamination in the cured product. This method also enables precise control of the curing temperature of the curing agent, achieving staged variable-temperature curing and solving the technical problems of uneven and uncontrollable temperature fields during the curing process. Simultaneously, the magnetic control method creates conditions for uniform heat dissipation within the curing system, improving curing efficiency and ensuring good performance of the cured product. Optimization of the traditional epoxy resin curing system through magnetic field control further reduces curing time and improves thermal conductivity.

[0105] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for curing epoxy resin, characterized in that: The process includes mixing an imidazole curing agent with epoxy resin, adding a magnetic filler dispersion and a thermal conductivity enhancer, then heating it uniformly, and applying a constant magnetic field first and then an alternating magnetic field during the heating process. The magnetic filler dispersion comprises magnetic filler, dispersant, and ethanol; The magnetic filler includes iron oxide nanoparticles or cobalt oxide nanoparticles; The magnetic filler dispersion includes a dispersant; The dispersant includes polyethylene glycol; The thermal conductivity enhancer includes modified short-cut carbon fibers; The method for preparing the modified short-cut carbon fiber includes the following steps: Short carbon fibers are oxidized with concentrated nitric acid and then surface-modified with silane coupling agent KH-550 to obtain the final product.

2. The epoxy resin curing method as described in claim 1, characterized in that: The imidazole curing agent includes 1-methylimidazol or ; The epoxy resin includes bisphenol A type epoxy resin.

3. The curing method for epoxy resin as described in claim 2, characterized in that: The particle size of the iron oxide nanoparticles is 50nm-200nm; The cobalt oxide nanoparticles have a particle size of 80-300 nm; The modified short-cut carbon fiber has a diameter of 7 μm and a length of 100 μm; The polyethylene glycol includes PEG-4000.

4. The curing method for epoxy resin as described in claim 2, characterized in that: The weight ratio of the epoxy resin to the imidazole curing agent is 87-100:3; The weight ratio of the epoxy resin to the magnetic filler is 87-100:20-23; The weight ratio of the epoxy resin to the thermal conductivity enhancer is 87-100:15; The weight ratio of the epoxy resin to the dispersant is 87-100:

2.

5. The curing method for epoxy resin as described in claim 1, characterized in that: The uniform heating includes the steps of heating to 60°C at a rate of 3°C / min under a constant magnetic field, then heating to 90°C at a rate of 1°C / min; and then heating to 100°C at a rate of 1°C / min under an alternating magnetic field.

6. The curing method for epoxy resin as described in claim 1, characterized in that: The strength of the constant magnetic field is 0.5T; The strength of the alternating magnetic field is 0.5T.

7. The polymer prepared by the curing method of epoxy resin as described in claim 1.

8. The application of the polymer as described in claim 7, characterized in that: It is used in the preparation of electromagnetic shielding materials.

9. The application of the polymer as described in claim 7, characterized in that: It is used in the preparation of motor insulation and encapsulation materials.

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