Industrial microwave oven melting device and method for resin for prepreg coating

Abstract

The application discloses a resin industrial microwave oven melting device and method for prepreg coating, and belongs to the technical field of composite material prepreg production. The device comprises an oven box body with a sealed heating cavity formed inside, a resin melting bin arranged in the sealed heating cavity and used for containing resin, a microwave generating system arranged on at least one side of the oven box body and used for emitting microwaves into the sealed heating cavity to heat the resin, and a stirring assembly arranged inside the resin melting bin and used for stirring the resin during melting. The resin industrial microwave oven melting device utilizes integral heating of microwaves and internal stirring to realize rapid and uniform melting of the resin, avoids overheating of a surface layer and insufficient internal melting, and improves melting efficiency and quality.

Description

Technical Field

[0001] This invention relates to the field of composite material prepreg production technology, and in particular to an industrial microwave oven melting apparatus and method for prepreg coating resin. Background Technology

[0002] Prepregs are key intermediate materials in the manufacturing process of advanced composite materials. The quality of resin melting during the coating process directly affects the uniformity of resin content, fiber impregnation, and the mechanical properties of the final product. Therefore, the stability and uniformity of the resin melting process have a significant impact on the quality of prepreg products.

[0003] Currently, the industry commonly uses traditional external heat conduction methods such as oven heating, heat transfer oil heating, or resistance wire heating to melt the resin used for prepreg coating. These methods rely on heat gradually transferring from the resin surface to the interior, and in actual production, they reveal the following technical shortcomings: First, the heating process proceeds from the surface inwards, resulting in uneven heating of the resin. The surface layer is prone to overheating or even aging and degradation, while the interior may not melt sufficiently, leading to large fluctuations in resin viscosity and making it difficult to ensure coating precision.

[0004] Secondly, the heating rate is relatively slow, and the resin stays at high temperature for a longer time, which can easily cause performance loss and thus affect the bonding strength and service life of the prepreg.

[0005] Third, temperature control is mostly in open-loop or semi-open-loop mode, making it difficult to achieve precise closed-loop regulation. Heat loss is significant, energy consumption is high, and the heating cycle is difficult to effectively match with the continuous coating production rhythm of prepreg.

[0006] Fourth, the manual feeding and transfer process involves many steps and is cumbersome. Impurities and moisture are easily introduced into the resin in an open environment, affecting the cleanliness of the molten resin and the stability of the process.

[0007] Therefore, there is an urgent need to develop a special device that is compatible with the prepreg production process and can achieve rapid, uniform, and controllable melting of resin. Summary of the Invention

[0008] To solve the above-mentioned technical problems, the present invention provides an industrial microwave oven melting device and method for prepreg coating resin, which utilizes the advantages of microwave heating such as integrity, speed and efficiency to achieve rapid, uniform and controllable melting of prepreg coating resin.

[0009] To achieve the above objectives, the present invention provides the following solution: An industrial microwave oven melting device for prepreg coating resin includes: an oven body with a sealed heating chamber formed inside; a resin melting chamber disposed within the sealed heating chamber for containing resin; a microwave generating system disposed on at least one side of the oven body for emitting microwaves into the sealed heating chamber to heat the resin in the resin melting chamber; and a stirring assembly disposed inside the resin melting chamber for stirring the resin during the melting process.

[0010] Optionally, the inner wall of the sealed heating cavity is provided with a microwave reflector and a microwave shielding layer. The microwave reflector is used to uniformly reflect microwaves into the sealed heating cavity, and the microwave shielding layer is used to confine the microwaves within the sealed heating cavity.

[0011] Optionally, the microwave generating system includes a first microwave generator and a second microwave generator, which are symmetrically arranged on both sides of the oven body for uniformly irradiating the resin melting chamber with microwaves.

[0012] Optionally, the stirring assembly includes a stirring mechanism, which includes a stirring shaft, a stirring motor, and a stirring paddle mounted on the lower end of the stirring shaft. The stirring motor drives the stirring paddle to rotate through the stirring shaft.

[0013] Optionally, the stirring assembly further includes a lifting mechanism connected to the stirring mechanism for driving the stirring mechanism to move up and down in the vertical direction, so that the stirring paddle stirs the resin at different depths within the resin melting chamber.

[0014] Optionally, the industrial microwave oven melting device for prepreg coating resin further includes a temperature detection unit and a temperature control unit; the temperature detection unit is disposed in the resin melting chamber or the sealed heating chamber and is used to detect the temperature of the resin in real time; the temperature control unit is connected to the temperature detection unit and the microwave generating system respectively, and is used to adjust the output power of the microwave generating system according to the comparison result between the measured temperature value fed back by the temperature detection unit and the preset target temperature value.

[0015] Optionally, the temperature control unit is a PID temperature controller, the temperature detection unit is an infrared temperature sensor, the detection end of the infrared temperature sensor extends into the interior of the resin melting chamber, and the PID temperature controller is connected to the infrared temperature sensor and the microwave generation system respectively.

[0016] Optionally, the industrial microwave oven melting device for prepreg coating resin further includes a control system, which is disposed on the oven body. The control system includes a microwave power adjustment unit, which is electrically connected to the microwave generating system and is used to adjust the output power of the microwave generating system.

[0017] Furthermore, the control system also includes an oven temperature monitoring and control unit and an oven current monitoring and control unit. The oven temperature monitoring and control unit is used to monitor the ambient temperature inside the sealed heating cavity, and the oven current monitoring and control unit is used to monitor the operating current of the microwave generating system.

[0018] Furthermore, the control system includes a stirring lifting button and a stirring rotation button. The stirring lifting button is signal-connected to the lifting mechanism and is used to control the lifting action of the stirring mechanism. The stirring rotation button is signal-connected to the stirring motor and is used to control the rotation start and stop of the stirring mechanism.

[0019] Optionally, the stirring motor is equipped with a speed regulator, which is electrically connected to the stirring motor and is used to adjust the rotational speed of the stirring paddle, wherein the rotational speed of the stirring paddle is set to 20 r / min.

[0020] Optionally, the resin melting chamber is made of polytetrafluoroethylene material that is resistant to high temperatures and has microwave permeability.

[0021] Furthermore, the industrial microwave oven melting device for prepreg coating resin also includes a radiator, which is installed outside the oven and is used to provide forced heat dissipation for the microwave generating system.

[0022] Furthermore, a heat insulation layer is provided between the inner wall of the sealed heating chamber and the outer wall of the resin melting chamber, the heat insulation layer being used to reduce heat loss during the melting process.

[0023] Furthermore, the oven body is provided with an openable oven door, and the oven door is provided with a door latch. The door latch is used to lock the oven door to the oven body during the melting process to maintain the sealed state of the sealed heating chamber.

[0024] A method for melting resin for prepreg coating, the method being carried out using an industrial microwave oven melting apparatus for prepreg coating resin as described in any of the above-mentioned claims, the method comprising the following steps: Step S1, Pre-treatment of material feeding: Add solid resin to the resin melting chamber set in the sealed heating chamber, close the oven door and lock the door buckle to make the sealed heating chamber in a sealed state; Step S2, Microwave Melting Heating and Stirring: The microwave generating system is started to emit microwaves into the sealed heating cavity to heat the resin in the resin melting chamber; at the same time, the stirring assembly is started to stir the resin during the melting process. Step S3, Discharge and Glue Coating: After the resin is melted to the target state, the molten resin is taken out from the resin melting chamber and transported to the prepreg coating equipment for glue coating operation.

[0025] Furthermore, in step S2, the microwave melting heating and stirring step employs a multi-stage stirring control strategy, including: Step S201, Initial melting stage: The microwave generating system heats the resin with a set power, the stirring component remains stationary, and the heating continues for a first preset time t1; Step S202, Critical Melting Stage: The stirring component starts to rotate at a first speed, and at the same time, the stirring component moves up and down in the vertical direction, continuously heating for a second preset time t2 until the resin forms a mobile phase; Step S203, Rapid melting and homogenization stage: Increase the rotation speed of the stirring component to a second rotation speed, which is higher than the first rotation speed, and continue stirring until microwave heating ends.

[0026] Furthermore, the first preset duration t1 is 1 minute and 50 seconds, the second preset duration t2 is 2 minutes and 15 seconds, the first rotation speed is 5~10 r / min, and the second rotation speed is 150~300 r / min.

[0027] Furthermore, in step S202, the load torque of the stirring assembly is detected in real time by a torque sensor installed on the stirring assembly or by monitoring the current feedback of the stirring motor; when the load torque drops below a preset threshold, it is determined that the resin has formed a mobile phase, and the process is allowed to proceed to step S203.

[0028] Furthermore, step S2 also includes a temperature closed-loop control step: The measured temperature value of the resin is collected in real time by a temperature detection unit installed in the resin melting chamber or the sealed heating chamber, and the measured temperature value is fed back to the temperature control unit. The temperature control unit compares the measured temperature value with a preset target temperature value, generates a control signal based on the comparison result, and adjusts the output power of the microwave generating system to maintain the measured temperature of the resin within the preset target temperature range.

[0029] Furthermore, the preset target temperature range is 60℃~85℃, and the deviation between the measured temperature and the preset target temperature is controlled within ±1℃.

[0030] Furthermore, in step S2, the output power of the microwave generating system is 300W~1000W, and the total microwave heating time is 3 minutes 50 seconds~6 minutes.

[0031] In step S2, after the microwave heating is completed, the stirring component continues to operate and continuously stirs the resin by raising and lowering it until the resin temperature drops to the safe discharge temperature and then the stirring stops.

[0032] Furthermore, in step S2, after microwave heating is completed, a temperature verification and reheating step is also included: Open the oven door and use a handheld infrared thermometer to verify the resin temperature at different locations in the resin melting chamber. If the measured temperature does not reach the preset target temperature, temporarily start the microwave generator system for short-term reheating until the temperature at all detection points meets the process requirements.

[0033] Furthermore, in step S1, the solid resin is epoxy resin for wind turbine blades, with a single batch processing quantity of 150 kg, and the resin is contained in a resin barrel made of polytetrafluoroethylene.

[0034] Compared with the prior art, the present invention discloses at least the following beneficial effects: The present invention provides an industrial microwave oven melting device for prepreg coating resin. A sealed heating chamber is formed within the oven body, into which a resin melting chamber is placed. A microwave generating system located on at least one side of the oven body emits microwaves into the sealed heating chamber, allowing the microwaves to directly penetrate the resin melting chamber and act on the resin interior. This achieves overall self-heating melting of the resin, fundamentally avoiding the problems of surface overheating and aging, and insufficient internal melting caused by traditional heat conduction methods that heat from the surface inwards. Simultaneously, a stirring component continuously agitates the resin during the melting process within the melting chamber, promoting rapid and uniform heat distribution within the resin and effectively removing air bubbles entrained in the molten resin, ensuring the homogeneity and density of the molten resin. Based on this structure, the device can rapidly and uniformly melt the resin within a short heating time, significantly reducing the resin's residence time at high temperatures, thereby reducing the risk of resin performance loss and effectively improving melting efficiency and quality. This provides a stable and uniform resin raw material for subsequent prepreg coating processes. Attached Figure Description

[0035] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0036] Figure 1 This is a schematic diagram of the structure of the industrial microwave oven melting device for prepreg coating resin of the present invention. Figure 1 ; Figure 2 This is a schematic diagram of the structure of the industrial microwave oven melting device for prepreg coating resin of the present invention. Figure 2 ; Reference numerals in the attached drawings: 1. Oven body; 2. First microwave generator; 3. Second microwave generator; 4. Oven door; 5. Control system; 6. Radiator; 7. Lifting mechanism; 8. Stirring mechanism; 9. Oven current monitoring and control unit; 10. Resin melting chamber; 11. Door latch; 12. Microwave power adjustment unit; 13. Infrared temperature sensor; 14. Stirring and lifting button; 15. Stirring and rotating button; 16. Oven temperature monitoring and control unit. Detailed Implementation

[0037] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0038] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0039] Example 1 Reference Figure 1 and Figure 2 As shown, this embodiment 1 provides an industrial microwave oven melting device for prepreg coating resin, including an oven body 1, which constitutes the main frame and external protective structure of the entire device. A sealed heating chamber is formed inside the oven body 1, serving as the core space for resin melting operations. A microwave reflector and a microwave shielding layer are sequentially laid on the inner wall of this sealed heating chamber. The microwave reflector uniformly reflects microwaves to all parts of the chamber, thereby improving the uniformity of microwave heating; the microwave shielding layer confines the microwaves within the sealed heating chamber, effectively preventing microwave leakage and ensuring production safety. A resin melting chamber 10 is fixedly installed at the center of the sealed heating chamber.

[0040] The oven body 1 is equipped with an openable oven door 4, which facilitates the operation of the operator to take out and put in the resin melting chamber 10 and related materials. The door is equipped with a door buckle 11, which is used to tightly lock the oven door 4 to the oven body 1 during the melting operation to maintain the sealed state of the closed heating chamber.

[0041] A control system 5 is fixedly installed on one side of the outer wall of the oven body 1. The control system 5 serves as the electrical and control core of the entire device and integrates or connects multiple functional modules, including a microwave power adjustment unit 12, an oven temperature monitoring and control unit 16, and an oven current monitoring and control unit 9.

[0042] The microwave power adjustment unit 12 is electrically connected to the microwave generating system and is used to adjust the microwave output power according to the received control signal. The microwave generating system includes a first microwave generator 2 and a second microwave generator 3, both of which are microwave magnetrons, symmetrically distributed on the opposite inner walls of the sealed heating cavity to achieve uniform microwave irradiation of the resin melting chamber 10.

[0043] The first microwave generator 2 and the second microwave generator 3 are electrically connected to the microwave power adjustment unit 12, respectively. The microwave power adjustment unit 12 continuously controls the microwave field strength by adjusting the electrical power output to each microwave magnetron.

[0044] In one specific embodiment, the resin melting chamber 10 is made of polytetrafluoroethylene material that is resistant to high temperatures and has high microwave penetration, so as to ensure that microwaves can efficiently penetrate the chamber wall and directly heat the internal resin.

[0045] Based on the above embodiments, the device further includes a PID temperature closed-loop control system. The PID temperature closed-loop control system includes an infrared temperature sensor 13 and a PID temperature controller (integrated within the control system 5). The detection end of the infrared temperature sensor 13 extends into the resin melting chamber 10 to collect temperature data in real time during the resin melting process.

[0046] The PID temperature controller is connected to both the infrared temperature sensor 13 and the microwave power adjustment unit 12. The PID temperature controller receives the measured temperature value from the infrared temperature sensor 13, compares it with a preset target temperature value, and automatically generates a power adjustment command based on the difference using PID calculation. This command is then transmitted to the microwave power adjustment unit 12, which adjusts the output power of the first microwave generator 2 and the second microwave generator 3 accordingly.

[0047] This closed-loop control mechanism enables precise control of the resin melting temperature, with temperature fluctuations controlled within ±1℃.

[0048] Based on the above embodiments, a stirring assembly is further provided inside the resin melting chamber 10. The stirring assembly includes a stirring mechanism 8 and a lifting mechanism 7. The stirring mechanism 8 includes a stirring shaft, a stirring motor, and a speed regulator (both the stirring motor and the speed regulator are located outside the oven body 1 or inside the control system 5). The stirrer extends from the top of the resin melting chamber 10 and penetrates into the interior of the chamber, with a stirring paddle installed at its lower end. The stirring motor drives the stirrer to rotate via the stirring shaft, and the speed regulator is electrically connected to the stirring motor to adjust the rotational speed of the stirring paddle.

[0049] In one specific embodiment, the rotation speed of the stirring motor can be set to a low speed of 20 r / min via a speed regulator to meet the stirring requirements during the epoxy resin melting process and avoid introducing too many air bubbles due to excessive speed. The stirring mechanism 8 is also equipped with a lifting drive unit, which is signal-connected to the oven stirring lifting button 14. By pressing the oven stirring lifting button 14, the operator can make the stirring mechanism 8 move up and down in the vertical direction, thereby allowing the stirring paddle to stir the resin at different depths within the resin melting chamber 10, promoting uniform heating of the resin and accelerating the removal of internal air bubbles.

[0050] In one specific embodiment, the lifting mechanism 7 includes a lifting motor and a lifting transmission component. The lifting motor is connected to the control system 5 via a signal. The outer wall panel of the control system 5 is provided with an oven stirring lifting button 14 and an oven stirring rotation button 15 for manual operation by the operator.

[0051] Reference Figure 2 As shown, a radiator 6 is also installed outside the oven body 1. The radiator 6 is used to forcibly dissipate the heat generated by the microwave generating system and other electrical components (such as the control system 5) during operation, so as to ensure the thermal stability and operational reliability of the device under continuous production conditions.

[0052] In another specific embodiment, a heat insulation layer is provided between the inner wall of the sealed heating chamber and the outer wall of the resin melting chamber 10. The heat insulation layer is made of a heat insulation material with low thermal conductivity, which is used to reduce heat loss during the melting process and reduce the overall energy consumption of the device.

[0053] Example 2 Embodiment 2 of the present invention provides a method for melting resin for prepreg coating, which is implemented using the industrial microwave oven melting device for prepreg coating resin described in Embodiment 1 above. The method includes the following steps: Step S1: Material pretreatment.

[0054] First, open the oven door 4. The operator releases the door latch 11 and opens the oven door 4. Then, push the resin bucket made of polytetrafluoroethylene (PTFE) into the resin melting chamber 10 inside the sealed heating chamber. Secure the resin bucket to the resin melting chamber 10 using a fixing mechanism to ensure the resin bucket does not shift during subsequent stirring and heating. Next, add the solid resin for prepreg coating to the resin bucket according to the fixed net weight required for the prepreg coating process. After adding the material, close the oven door 4 and lock the door latch 11 to restore the sealed heating chamber to a sealed state.

[0055] Step S2: Microwave melting heating and multi-stage stirring control.

[0056] After confirming that the oven door 4 is closed properly, the operator sets the required melting temperature and microwave power parameters through the control system 5. The microwave generation system is then activated, and the first microwave generator 2 and the second microwave generator 3 simultaneously emit microwaves into the sealed heating cavity. The microwaves penetrate the walls of the polytetrafluoroethylene resin tank and the resin melting chamber 10, directly acting on the interior of the resin.

[0057] In this embodiment, step S2 employs a multi-stage stirring control strategy to match the rheological properties of the resin at different melting stages, specifically including: Step S201, Initial Melting Stage: The microwave generating system heats the resin at a set power, while the stirring component remains stationary, and heating continues for a first preset duration t1. During this stage, the resin is still predominantly solid, and the stirring paddle is under significant load. The goal of this stage is to allow the resin surface and shallow layers to rapidly absorb microwave energy and begin to soften, creating conditions for subsequent stirring. The first preset duration t1 is determined based on the type and batch size of the resin; for example, t1 ranges from 1 minute 30 seconds to 2 minutes 30 seconds.

[0058] Step S202, Critical Melting Stage: The stirring assembly starts rotating at a first rotational speed, while simultaneously moving vertically up and down, continuously heating for a second preset time t2 until the resin forms a mobile phase. During this stage, the load torque of the stirring assembly is detected in real time by a torque sensor mounted on the stirring assembly or by monitoring the current feedback of the stirring motor; when the load torque drops below a preset threshold, it is determined that the resin has formed a mobile phase, allowing entry into the next stage. The first rotational speed is an ultra-low speed, exemplarily 5~10 r / min; the second preset time t2 is determined according to the resin type and batch size, exemplarily ranging from 2 minutes to 3 minutes.

[0059] Step S203, Rapid Melting and Homogenization Stage: Increase the rotation speed of the stirring component to a second speed, which is higher than the first speed, and continue stirring until microwave heating ends. This stage generates strong convection and shearing effects, accelerating the rapid melting of the deep solid resin inside the tank, while effectively breaking down and eliminating air bubbles entrained in the resin, and ensuring uniform viscosity and temperature of the resin throughout the tank, avoiding localized overheating. The second rotation speed is exemplarily 150~300 r / min.

[0060] Step S3: Closed-loop temperature control and post-treatment stirring.

[0061] From the moment microwave heating begins, the infrared temperature sensor 13 continuously collects real-time temperature data of the resin inside the resin melting chamber 10 and transmits this temperature data to the PID temperature controller. The PID temperature controller compares the received measured temperature value with the preset target melting temperature value, and automatically generates a control signal based on the deviation between the two through PID calculation, and outputs this signal to the microwave power adjustment unit 12. The microwave power adjustment unit 12 adjusts the output power of the first microwave generator 2 and the second microwave generator 3 in real time according to the received control signal, so that the measured temperature always fluctuates around the preset target value. Through this closed-loop control, the melting temperature is maintained constant within the set range; for example, the temperature fluctuation is controlled within ±1℃. The preset target temperature range is, for example, 60℃~85℃.

[0062] When microwave heating has reached the predetermined time, the microwave generating system is turned off. The total microwave heating time is, for example, 3 minutes and 50 seconds to 6 minutes. However, the stirring component continues to operate, and the operator continues to press the oven stirring and lifting button 14 to make the stirring mechanism 8 continuously move up and down to maintain uniform resin temperature and prevent local cooling and solidification. At the same time, after turning off the microwave, the operator can open the oven door 4 and use a handheld infrared thermometer to verify the resin temperature at different locations inside the barrel. If the measured temperature does not reach the target temperature, the microwave generating system can be temporarily started through the control system 5 for short-term supplemental heating until the temperature at all detection points meets the process requirements. When the infrared temperature sensor 13 shows that the resin temperature has dropped to the safe discharge temperature, the stirring operation is stopped.

[0063] Step S4: Discharge and apply adhesive.

[0064] The operator opens the door latch 11 and the oven door 4, pushing the polytetrafluoroethylene resin bucket containing molten resin from the resin melting chamber 10 to the outside of the oven body 1. The resin bucket is then transported to the prepreg coating equipment station, where the molten resin is introduced into the coating system for subsequent prepreg coating operations.

[0065] Step S5: Shut down and clean.

[0066] Once the production schedule is completed, the microwave generator, stirring assembly, and PID temperature control system are turned off in sequence, and the power supply to the entire machine is disconnected. After the equipment has cooled naturally to room temperature, the operator cleans the resin melting chamber 10, stirring mechanism 8, and any residual resin in the resin tank, and cleans and maintains the inside of the sealed heating chamber in preparation for the next production run.

[0067] In the above method, the output power of the microwave generating system is, for example, 300W~1000W (for laboratory or small-batch scenarios) or higher, up to 12KW~15KW (for industrial large-batch scenarios). The specific power is set comprehensively based on the type of resin, the single batch processing volume, and the target heating rate. The solid resin is, for example, a thermosetting resin system for prepreg coating, such as epoxy resin, polyurethane resin, polyester resin, or composite resin.

[0068] Example 3 Example 3 provides an application case of microwave melting of epoxy resin for wind turbine blades. The method of melting resin for prepreg coating described in Example 2 is used to illustrate the process parameters and effects of this method in the mass melting of epoxy resin for wind turbine blades.

[0069] In this embodiment, epoxy resin for wind turbine blades is selected as the prepreg coating material. The batch processing volume is 150 kg, which is placed in a 200 L standard resin barrel made of polytetrafluoroethylene and then placed in the resin melting chamber 10. The target melting temperature is set to 60 °C. The microwave generation system is configured with 8 microwave generators (4 sets each of the first microwave generator 2 and the second microwave generator 3) running simultaneously, with a total output power of 12 KW and a microwave frequency of 2450 MHz.

[0070] The melting process is as follows: After confirming that the oven door 4 is closed, the microwave generator is started to heat the resin, and the stopwatch on the equipment begins to count. When the microwave heating reaches 1 minute and 50 seconds (i.e., the first preset duration t1 = 1 minute and 50 seconds), the operator starts the stirring assembly by pressing the oven stirring rotation button 15. At this time, the stirring shaft starts to rotate at a low speed (first speed, about 5~10 r / min), and at the same time, the oven stirring lifting button 14 is pressed to make the stirring paddle move up and down to stir at different depths in the resin tank. When the heating reaches 2 minutes and 15 seconds (i.e., the second preset duration t2 = 2 minutes and 15 seconds), the stirring shaft can rotate at a uniform speed, indicating that the resin has formed a sufficient mobile phase. At this time, the stirring speed is increased to 150~300 r / min (second speed) through the speed regulator. When the heating reaches 3 minutes and 50 seconds, the microwave heating is stopped, the stirring assembly continues to run, the oven door 4 is opened, and the temperature of the resin at different positions in the tank is checked and verified using a handheld infrared thermometer to confirm that the resin temperature reaches 60℃ after melting. If the measured temperature does not reach the target temperature (e.g., 1°C difference), the microwave generator system will be temporarily activated by the control system 5 for short-term supplementary heating (e.g., reheating for 1 minute) until the temperature at all detection points meets the process requirements.

[0071] Testing revealed that temperature fluctuations throughout the melting process were controlled within ±1℃. The melted epoxy resin exhibited a uniform flow state, with no visible degradation or discoloration, no internal air bubbles, and consistent output viscosity. After the molten resin was guided to the coating equipment, the resulting prepreg product showed a resin content deviation controlled within ±1%. Production statistics show that using the method described in this embodiment increases production efficiency by 60% and reduces energy consumption by 45% compared to traditional oven heating methods. Furthermore, the entire melting process is completed within a sealed chamber, effectively isolating external impurities and moisture, thus ensuring the cleanliness of the resin.

[0072] As a further extension of the above solution, the device and method of this invention are also applicable to microwave-assisted hot pressing curing of aerospace epoxy composites. The microwave frequency is selected from the 2450MHz industrial band, shortening the curing cycle by 70%~80% compared to traditional autoclaves, achieving a final curing degree of over 95%, with a matching autoclave pressure of 0.3~0.6MPa, and a maximum daily production capacity of 5000m³. 2 In the microwave curing scenario of epoxy E51+650 polyamide system, the four parameters of output power, heating time, interval time and heating cycle are controlled in real time by PLC. The high power level is selected (under the premise of no explosive polymerization / burning), and a long heating cycle and short interval time are configured. The curing time is shortened by 2 / 3 compared with traditional thermosetting. The tensile properties of the casting are basically the same as those of thermosetting products.

[0073] Example 4 Example 4 provides a case study of continuous polyurethane / epoxy composite resin microwave melting mass production application. The method of melting resin for prepreg coating described in Example 2 is used to verify the melting efficiency and product quality of the method in a large-scale, continuous production scenario.

[0074] In this embodiment, the resin to be melted is a polyurethane / epoxy composite resin, with a single batch processing volume of 200 kg. It is placed in a 200 L standard resin container and then placed into the resin melting chamber 10. The microwave generation system is configured with eight microwave generators (four sets each of the first microwave generator 2 and the second microwave generator 3) operating simultaneously, with a total output power of 12 kW, a microwave frequency of 2450 MHz, and a target melting temperature of 60°C to 85°C.

[0075] The melting process was carried out according to the multi-stage stirring control strategy described in Example 2: when microwave heating reached 1 minute and 50 seconds, the stirring component was started to rotate and stir at a low speed (5~10 r / min); when heating reached 2 minutes and 15 seconds, the stirring shaft rotated at a constant speed, and the stirring speed was increased to 150~300 r / min; when heating reached 3 minutes and 50 seconds, microwave heating was stopped, stirring continued, and the oven door 4 was opened to verify the temperature uniformity using a handheld infrared thermometer.

[0076] Testing revealed that microwave irradiation for only 5-10 minutes achieved the melting effect that would normally require 6 hours of baking at 120°C. The melted resin system exhibited uniform internal temperature and no localized clumping. The molten composite resin was then transported to the subsequent cross-linking molding process. Testing showed that the elastic modulus of the molded composite material reached 1101 MPa. This example demonstrates that this melting method is also applicable to polyurethane / epoxy composite resin systems and can significantly improve melting efficiency and product performance in large-scale continuous production.

[0077] As an optional implementation method, for general microwave melting of 200kg drums of resin, the VYS-15HO cabinet-type equipment can be used, with a total microwave power of 15KW, a temperature adjustment range of 0~350℃, and a single batch processing time of 30~40 minutes, which can also achieve good melting results.

[0078] Example 5 Example 5 provides an application case of microwave reaction of pharmaceutical solid-phase synthetic resin. It is implemented by adapting the resin melting method for prepreg coating described in Example 2 to expand the application of this method in the field of pharmaceutical chemical solid-phase synthesis.

[0079] In this embodiment, polystyrene resin loaded with active amines is used as a solid carrier, dispersed in dichloroethane solvent, and placed into a reaction vessel made of polytetrafluoroethylene. This reaction vessel is then placed in the resin melting chamber 10. The oven door 4 is closed and the door latch 11 is locked. Microwave heating parameters are set via the control system 5: microwave frequency is 2450MHz, target reaction temperature is 140℃, and output power is adjusted within the range of 300W to 1000W according to reaction requirements.

[0080] The reaction process employs a segmented irradiation strategy: microwave heating is paused after each irradiation cycle lasting 2 minutes, and the oven door 4 is opened to sample and monitor the reaction progress. After sampling, the door is closed, and the next irradiation cycle continues. During this process, the stirring assembly maintains continuous stirring at a speed of 20 r / min. The lifting mechanism 7 drives the stirring paddle to move up and down at different depths within the reaction vessel to ensure sufficient contact between the solid support and the reaction liquid.

[0081] Testing revealed that the reaction between the solid-phase support resin and isocyanate could achieve complete cleavage under irradiation at 140°C for 15 minutes without any carrier degradation. The complete reaction between the amine groups and isocyanate was completed in just 12 minutes (6 rounds of irradiation), while traditional room-temperature stirred reactions typically require several hours to achieve a similar conversion rate. The final target product, as determined by high-performance liquid chromatography (HPLC), showed significantly higher purity than conventional synthesis methods. This example validates the efficiency and practicality of this melting method in pharmaceutical solid-phase resin synthesis, particularly suitable for reactions involving aniline reagents that are difficult to react under conventional conditions.

[0082] Example 6 Example 6 provides an application case of microwave curing of unsaturated polyester resin (artificial quartz system). The method of resin melting for prepreg coating described in Example 2 is adapted and implemented to verify the advantages of microwave heating technology in the field of resin curing.

[0083] It should be noted that the device described in Example 1 has been adapted in this embodiment: the resin melting chamber 10 is replaced with a support tray suitable for placing flat blanks, and there is no need to set up a stirring assembly. The rest of the structure is consistent with that of Example 1. Accordingly, the stirring control step of the method described in Example 2 is omitted in this embodiment.

[0084] In this embodiment, the resin to be cured is an unsaturated polyester resin (UPR) / SiO2 artificial quartz stone system. First, the unsaturated polyester resin with the curing agent is thoroughly mixed with the quartz sand filler. Then, the mixture is spread into a quartz stone slab blank of a specified thickness (e.g., 15mm~30mm). The blank, together with the supporting tray, is placed into the sealed heating chamber, the oven door 4 is closed, and the door buckle 11 is locked.

[0085] The microwave generation system is activated by the control system 5, and the first microwave generator 2 and the second microwave generator 3 irradiate symmetrically. The microwave frequency is 2450MHz, and the total output power is adjusted within the range of 2KW to 12KW according to the size and weight of the preform. Utilizing the volumetric heating characteristics of microwaves, the resin is simultaneously heated and crosslinked from the inside out, effectively avoiding the internal stress problems that are easily caused by poor thermal conductivity and large internal and external temperature differences in traditional thermosetting.

[0086] Actual production verification shows that the microwave curing process in this embodiment only requires 12 minutes to achieve complete curing, while traditional thermosetting methods require 1 hour. Tests on the cured quartz stone slabs revealed significantly improved flexural properties and impact strength compared to traditional thermosetting products. Furthermore, comparisons using infrared spectroscopy and cure degree testing demonstrate that microwave curing does not alter the final cure degree of the resin, and the reaction product structure is completely consistent with that of thermosetting.

[0087] Example 7 Example 7 provides an application case of microwave chemical recycling of acrylic resin. It is implemented by adapting the resin melting method for prepreg coating described in Example 2 to achieve green recycling of waste acrylic resin.

[0088] It should be noted that the apparatus described in Example 1 has been adapted in this embodiment: the resin melting chamber 10 is replaced with a microwave decomposition reaction vessel suitable for containing waste acrylic resin fragments, and a condensation recovery system is added in the sealed heating chamber to collect the monomer vapor generated by decomposition. The stirring assembly can be turned off or removed as needed for the reaction. Accordingly, the stirring control step of the method described in Example 2 is omitted in this embodiment.

[0089] In this embodiment, the sorted and crushed waste acrylic resin (polymethyl methacrylate, PMMA) fragments are first loaded into a microwave decomposition reaction vessel, placed inside a sealed heating chamber, and the oven door 4 is closed and locked with the door latch 11. The microwave parameters are precisely controlled by the control system 5, with a microwave frequency of 2450MHz, and the output power adjusted within the range of 1KW to 15KW according to the amount of resin processed. The heating temperature is controlled between 300℃ and 400℃.

[0090] The internal frictional heat generated by the absorption of microwaves by the polar molecules of acrylic resin is used to directionally trigger the depolymerization reaction of the resin, causing the polymer chain segments to break at specific chemical bond positions, generating methyl methacrylate (MMA) monomers. The monomer vapor generated during the reaction is collected through a condensation and recovery system, and the unreacted residue is recycled as fuel.

[0091] Practical operation has verified that this embodiment can efficiently decompose waste acrylic resin into repolymerizable MMA monomer raw materials without the high energy consumption conditions of traditional high-temperature pyrolysis (usually requiring above 500°C), achieving a monomer recovery rate of over 90% and realizing "zero-waste" recycling of resin materials. This embodiment demonstrates that the device and method have broad application prospects in the field of waste resin resource recycling.

[0092] Examples 3 to 7 above are all based on the device described in Example 1 and the method described in Example 2 of this invention, or implemented or adapted. However, the scope of protection of this invention is not limited to the specific application scenarios described above. Those skilled in the art can apply this device and method to microwave processing of other resin systems without departing from the spirit of this invention, such as microwave drying of PVC paste resin powder (working power supply three-phase five-wire 380V±10%, microwave frequency 2450MHz±50MHz, total power 40KW continuously adjustable, drying temperature 80~120℃ controllable, transmission speed 0~5m / min frequency conversion speed regulation, dehydration efficiency 40 kg / hour, microwave leakage ≤5mw / cm). 2 Scenarios such as those that meet national standards should all be considered extended applications falling under the embodiments of this invention.

[0093] In the description of this invention, it should be understood that the terms "longitudinal", "lateral", "up", "down", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this invention, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this invention.

[0094] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A microwave oven melting device for prepreg coating resin, characterized in that, include: The oven body (1) has a sealed heating chamber inside. A resin melting chamber (10) is disposed within the sealed heating chamber and is used to contain resin; A microwave generating system is disposed on at least one side of the oven body (1) and emits microwaves into the sealed heating cavity to heat the resin in the resin melting chamber (10); A stirring assembly is installed inside the resin melting chamber (10) to stir the resin during the melting process.

2. The industrial microwave oven melting apparatus for prepreg coating resin according to claim 1, characterized in that, The inner wall of the sealed heating cavity is lined with a microwave reflector and a microwave shielding layer. The microwave reflector is used to uniformly reflect microwaves into the sealed heating cavity, and the microwave shielding layer is used to confine the microwaves within the sealed heating cavity.

3. The industrial microwave oven melting apparatus for prepreg coating resin according to claim 1, characterized in that, The microwave generating system includes a first microwave generator (2) and a second microwave generator (3). The first microwave generator (2) and the second microwave generator (3) are symmetrically arranged on both sides of the oven body (1) for uniform microwave irradiation of the resin melting chamber (10).

4. The industrial microwave oven melting apparatus for prepreg coating resin according to claim 1, characterized in that, The stirring assembly includes a stirring mechanism (8), which includes a stirring shaft, a stirring motor, and a stirring paddle mounted on the lower end of the stirring shaft. The stirring motor drives the stirring paddle to rotate through the stirring shaft.

5. The industrial microwave oven melting apparatus for prepreg coating resin according to claim 4, characterized in that, The stirring assembly also includes a lifting mechanism (7), which is connected to the stirring mechanism (8) and is used to drive the stirring mechanism (8) to move up and down in the vertical direction so that the stirring paddle stirs the resin at different depths in the resin melting chamber (10).

6. The industrial microwave oven melting apparatus for prepreg coating resin according to any one of claims 1 to 5, characterized in that, It also includes a temperature detection unit and a temperature control unit; The temperature detection unit is located in the resin melting chamber (10) or the sealed heating chamber and is used to detect the temperature of the resin in real time. The temperature control unit is connected to the temperature detection unit and the microwave generating system respectively, and is used to adjust the output power of the microwave generating system according to the comparison result between the measured temperature value fed back by the temperature detection unit and the preset target temperature value.

7. The industrial microwave oven melting apparatus for prepreg coating resin according to claim 6, characterized in that, The temperature control unit is a PID temperature controller, and the temperature detection unit is an infrared temperature sensor (13). The detection end of the infrared temperature sensor (13) extends into the resin melting chamber (10). The PID temperature controller is connected to the infrared temperature sensor (13) and the microwave generation system respectively.

8. The industrial microwave oven melting apparatus for prepreg coating resin according to claim 6, characterized in that, It also includes a control system (5), which is installed on the oven body (1). The control system (5) includes a microwave power adjustment unit (12), which is electrically connected to the microwave generating system and is used to adjust the output power of the microwave generating system.

9. A method for melting resin for prepreg coating, based on the industrial microwave oven melting apparatus for prepreg coating resin according to any one of claims 1 to 8, characterized in that, Includes the following steps: Step S1, Pre-treatment of material feeding: Add solid resin to the resin melting chamber (10) set in the sealed heating chamber, close the oven door (4) and lock the door buckle (11) to make the sealed heating chamber in a sealed state; Step S2, Microwave Melting Heating and Stirring: Start the microwave generating system to emit microwaves into the sealed heating cavity to heat the resin in the resin melting chamber (10); at the same time, start the stirring assembly to stir the resin during the melting process; Step S3, Discharge and Glue Coating: After the resin is melted to the target state, the molten resin is taken out from the resin melting chamber (10) and transported to the prepreg coating equipment for coating operation.

10. The method for melting resin for prepreg coating according to claim 9, characterized in that, In step S2, the microwave melting heating and stirring step employs a multi-stage stirring control strategy, including: Step S201, Initial melting stage: The microwave generating system heats the resin with a set power, the stirring component remains stationary, and the heating continues for a first preset time t1; Step S202, Critical Melting Stage: The stirring component starts to rotate at a first speed, and at the same time, the stirring component moves up and down in the vertical direction, continuously heating for a second preset time t2 until the resin forms a mobile phase; Step S203, Rapid melting and homogenization stage: Increase the rotation speed of the stirring component to a second rotation speed, which is higher than the first rotation speed, and continue stirring until microwave heating ends.

Images