Polymer particle curing system and method

Abstract

The invention relates to the field of high polymer material processing, and discloses a high polymer particle curing system and method. The curing system comprises: a pretreatment bin provided with a first feed port and a first discharge port; the conveying mechanism is arranged in the pretreatment bin; the microwave generating device is arranged in the pretreatment bin and located on one side of the conveying mechanism, and the microwave generating device faces the conveying mechanism and is used for emitting microwaves to the conveying mechanism; the stock bin is communicated with the first discharge port to receive the polymer particles, and the interior of the stock bin is used for keeping the curing temperature; and the stirring mechanism is arranged in the stock bin and is used for stirring the polymer particles. The polar molecules are utilized to generate heat through high-speed vibration, the transfer process of heat conduction or heat convection is not needed, internal and external synchronous heating of particles can be achieved, meanwhile, the reaction rate of NCO groups can be kept consistent, and the curing degree is highly unified. And the material bin receives the heated particles, so that the subsequent curing reaction of the particles is completed in a constant-temperature environment.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of polymer material processing, in particular to a polymer particle curing system and method. BACKGROUND

[0002] Thermoplastic polyurethane (TPU) and other polymer materials have a wide range of application scenarios, and in their actual application, the stability of mechanical properties directly affects product quality. The curing process is a key link for targeted improvement of mechanical properties after polymer particle forming.

[0003] In related technologies, polymer particles are usually cured in a silo. Specifically, hot air is introduced into the silo during the curing process, and the polymer particles are stirred.

[0004] However, the silo temperature of this curing method is uneven, which can cause the curing degree of polymer particles to be different, resulting in fluctuations in product performance. In addition, the silo curing process may cause local overheating, leading to melting and caking of polymer particles. SUMMARY

[0005] Therefore, the present application provides a polymer particle curing system and method to solve or improve the problem of uneven curing degree of polymer particles and caking of polymer particles in related technologies.

[0006] In a first aspect, the present application provides a polymer particle curing system for curing polymer particles containing polar groups, comprising: a pretreatment bin provided with a first inlet and a first outlet; a conveying mechanism arranged in the pretreatment bin and used for conveying the polymer particles between the first inlet and the first outlet; a microwave generating device arranged in the pretreatment bin and located on one side of the conveying mechanism, the microwave generating device facing the conveying mechanism and used for emitting microwaves to the conveying mechanism to heat the polymer particles to a curing temperature; a silo in communication with the first outlet to receive the polymer particles, the silo being used to maintain the curing temperature; a stirring mechanism arranged in the silo and used for stirring the polymer particles.

[0007] In an optional embodiment, the pretreatment bin is provided with at least two treatment chambers, and the at least two treatment chambers are arranged in sequence on one side of the conveying mechanism along the conveying direction of the conveying mechanism, and each treatment chamber is provided with the microwave generating device and an opening facing the conveying mechanism. The microwave generating devices are arranged in sequence along the conveying direction, and each microwave generating device is used to emit microwave to the polymer particles in sequence along the conveying direction to gradually heat the polymer particles.

[0008] In an alternative embodiment, the power of the microwave generating device of each processing chamber decreases in sequence along the conveying direction. And / or, the power of at least one pair of adjacent microwave generating devices is different.

[0009] In an alternative embodiment, the span of the processing chamber near the first discharge port in the conveying direction is greater than the span of the remaining processing chambers in the conveying direction. And / or, the span of at least one pair of adjacent processing chambers in the conveying direction is different.

[0010] In an alternative embodiment, the microwave generating device near the first inlet port increases the temperature of the polymer particles to a value greater than the temperature value increased by the remaining microwave generating devices. And / or, the temperature value of the polymer particles increased by at least one pair of adjacent microwave generating devices is different.

[0011] In an alternative embodiment, the polymer particle curing system further comprises: A temperature detection device arranged in the pre-treatment bin and used to detect the temperature value of the polymer particles. A control system connected to the temperature detection device and the microwave generating device, and the control system controls the power of the microwave generating device based on the temperature value.

[0012] In an alternative embodiment, the bin wall of the bin is provided with: An air inlet for the heated air to enter the bin; An air outlet for the gas in the bin to be discharged.

[0013] In an alternative embodiment, the polymer particle curing system further comprises a screening device, and the outlet of the screening device is in communication with the first inlet port.

[0014] In a second aspect, the present application also provides a curing method for curing polymer particles containing polar groups, comprising: Microwave pre-treatment of the polymer particles to heat the polymer particles to a curing temperature by using microwave; Introducing the polymer particles reaching the curing temperature into a bin, introducing hot air into the bin to keep the polymer particles at the curing temperature, and stirring the polymer particles.

[0015] In one optional embodiment, the polymer particles are subjected to at least two microwave pretreatments to gradually heat the polymer particles, wherein: The power of each microwave preprocessing step gradually decreases; And / or, the initial microwave pretreatment increases the temperature of the polymer particles by a greater value than the subsequent microwave pretreatments. And / or, the duration of the last microwave preprocessing is longer than the duration of the remaining microwave preprocessing.

[0016] The polymer particle ripening system provided by this invention employs microwave heating. Microwave energy directly acts on the polar groups inside the polymer particles, such as the NCO groups in TPU. Heat is generated by the high-speed vibration of polar molecules, eliminating the need for heat conduction or convection, and achieving simultaneous heating inside and outside the particles. The microwave generator is oriented towards the conveying mechanism; the movement of the particles during conveying avoids uneven heating, ensuring that each polymer particle receives microwave energy uniformly, ultimately reaching a consistent ripening temperature.

[0017] Furthermore, by utilizing the uniformity of microwave heating, the reaction rate of NCO groups can be kept consistent, and the degree of ripening can be highly uniform, thus avoiding performance fluctuations caused by uneven ripening from the root. This is especially suitable for polymer materials that require high ripening consistency.

[0018] In addition, the pretreatment chamber rapidly heats the particles to the curing temperature using microwaves. Microwave heating is much faster than hot air heating, which shortens the heating time. The hopper receives the heated particles and, while maintaining the curing temperature, continuously stirs them through a stirring mechanism. This ensures that the particles complete the subsequent curing reaction in a constant temperature environment and further guarantees uniform heating.

[0019] In addition, as long as the microwave power and conveying speed are set to match, the particles can be precisely heated to the ripening temperature. The heated particles do not need to be heated or dried in the silo using air that is higher than the ripening temperature, and there is no premise of local overheating. This can fundamentally prevent the particles from melting and sticking together in the silo.

[0020] The polymer particle ripening method provided by this invention contains the same features as the polymer particle ripening system, and therefore also contains the corresponding advantages of the polymer particle ripening system. Attached Figure Description

[0021] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0022] Figure 1 This is a schematic diagram of the structure of the polymer particle ripening system provided in an embodiment of the present invention.

[0023] Explanation of reference numerals in the attached figures: 1. Pretreatment chamber; 101. First feed inlet; 102. First discharge outlet; 2. Conveying mechanism; 3. Microwave generator; 4. Hopper; 401. Second feed inlet; 402. Second discharge outlet; 403. Air inlet; 404. Air outlet; 5. Stirring mechanism; 6. Processing chamber; 7. Baffle; 8. Temperature detection device; 9. Screening device; 10. Heating device; 11. Guide plate. Detailed Implementation

[0024] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, 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, 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.

[0025] In related technologies, polymer particles are typically matured in a silo. Specifically, hot air is introduced into the silo during the maturity process, and the polymer particles are stirred.

[0026] However, the uneven temperature in the hopper during this curing process can lead to inconsistent curing levels of polymer particles, resulting in fluctuations in product performance. For example, for soft TPU grades, which typically have a high polyol content of 60wt%-80wt%, the residual NCO groups react slowly. Uneven hopper temperatures and inconsistent curing levels cause fluctuations in the performance of the cured particles.

[0027] In addition, localized overheating may occur during the curing process, causing the polymer particles to melt and clump together. This is because the silo has a large volume, and in order to ensure that all polymer particles in the silo reach the curing temperature, the temperature of the hot air inlet of the silo must be higher than the curing temperature. Insufficient stirring and uneven heating can lead to localized excessively high temperatures, resulting in melting and adhesion.

[0028] To address or improve the problems of inconsistent ripening degrees and agglomeration of polymer particles in related technologies, this invention provides a polymer particle ripening system and method.

[0029] The following reference Figure 1 The polymer particle ripening system provided in the embodiments of the present invention will be described.

[0030] Specifically, the polymer particle curing system is used to cure polymer particles containing polar groups, such as TPU particles, in which NCO groups are polar groups. The polymer particle curing system includes a pretreatment chamber 1, a conveying mechanism 2, a microwave generator 3, a hopper 4, and a stirring mechanism 5.

[0031] The pretreatment chamber 1 is provided with a first inlet 101 and a first outlet 102. Optionally, the pretreatment chamber 1 is configured as a box structure, with the first inlet 101 and the first outlet 102 respectively located at both ends of the pretreatment chamber 1.

[0032] The conveying mechanism 2 is located inside the pretreatment chamber 1 and is used to convey polymer particles between the first inlet 101 and the first outlet 102. That is, the conveying mechanism 2 extends along the direction from the first inlet 101 to the first outlet 102 and is used to convey the polymer particles entering from the first inlet 101 to the first outlet 102 for discharge.

[0033] A microwave generator 3 is located inside the pretreatment chamber 1 and is situated on one side of the conveying mechanism 2. The microwave generator 3 faces the conveying mechanism 2 and is used to emit microwaves to the conveying mechanism 2 to heat the polymer particles to the ripening temperature.

[0034] The hopper 4 is connected to the first discharge port 102 to receive polymer particles. Specifically, the hopper 4 is used to receive polymer particles discharged from the first discharge port 102. The hopper 4 is used to maintain the curing temperature.

[0035] The stirring mechanism 5 is located inside the hopper 4 and is used to stir polymer particles.

[0036] In this embodiment, microwave heating is employed. Microwave energy directly acts on the polar groups inside the polymer particles, such as the NCO groups in TPU. Heat is generated by the high-speed vibration of polar molecules, eliminating the need for heat conduction or convection, thus achieving simultaneous heating inside and outside the particles. The microwave generator 3 is oriented towards the conveying mechanism 2. During the conveying process, the particles move, preventing uneven heating and ensuring that each polymer particle receives microwave energy uniformly, ultimately reaching a consistent ripening temperature.

[0037] Furthermore, by utilizing the uniformity of microwave heating, the reaction rate of NCO groups can be kept consistent, and the degree of ripening can be highly uniform, thus avoiding performance fluctuations caused by uneven ripening from the root. This is especially suitable for polymer materials that require high ripening consistency.

[0038] In addition, the pretreatment chamber 1 rapidly heats the particles to the curing temperature using microwaves. The microwave heating rate is much higher than that of hot air heating, which can shorten the time required for the heating stage. The hopper 4 receives the heated particles and, while maintaining the curing temperature, continuously stirs them through the stirring mechanism 5. This ensures that the particles complete the subsequent curing reaction in a constant temperature environment and further guarantees that the particles are heated evenly.

[0039] In addition, as long as the microwave power and conveying speed are set to match, the particles can be precisely heated to the ripening temperature. The heated particles do not need to be heated or dried in the hopper 4 with air that is higher than the ripening temperature. There is no premise of local overheating, which can fundamentally prevent the particles from melting and sticking together in the hopper.

[0040] The core function of the pretreatment chamber 1 is to rapidly heat polymer particles to the curing temperature using microwaves, rather than completing the entire curing reaction. Microwave heating is fast (polar molecules generate heat directly without heat transfer loss), and precise heating of the particles can be achieved with only a short conveying path. This avoids the need to lengthen the conveying mechanism 2 to extend the curing time, thus controlling the floor space of the pretreatment chamber 1 from the source.

[0041] The core function of hopper 4 is to maintain the curing temperature, allowing the heated granules to complete subsequent curing reactions in a constant-temperature environment, such as the full reaction of NCO groups in TPU. Since hopper 4 has no heating stage, it only requires curing air at the same temperature as the curing process to maintain the hopper temperature, thus shortening the overall residence time and reducing the hopper size and floor space. This combination of "small-footprint heating and small-volume curing" can meet the throughput requirements of industrial production while avoiding the problem of excessive volume or length caused by a single heating chamber balancing "heating and curing," significantly reducing the floor space of the entire curing system and adapting to the compact layout of factory workshops.

[0042] In summary, the polymer particle curing system provided in this application is particularly suitable for curing soft-grade TPU with a Shore hardness of 60A-95A.

[0043] In some embodiments provided by the present invention, the microwave generating device 3 includes a magnetron.

[0044] In this embodiment, the magnetron can directly convert electrical energy into microwave energy, with high energy conversion efficiency and the ability to quickly output stable microwave energy. This perfectly matches the requirement of the pretreatment chamber 1 to "rapidly heat the particles to the ripening temperature," that is, relying on the high-frequency microwaves output by the magnetron, the polar groups inside the polymer particles can be directly driven to vibrate at high speed to generate heat, achieving "simultaneous heating inside and outside the particles," shortening the heating time and improving the efficiency of the ripening process.

[0045] In some embodiments provided by the present invention, the pretreatment chamber 1 is provided with at least two processing chambers 6, which are arranged sequentially along the conveying direction of the conveying mechanism 2, and both processing chambers 6 are located on one side of the conveying mechanism 2. Each processing chamber 6 is provided with an opening facing the conveying mechanism 2, and each processing chamber 6 is provided with a microwave generating device 3, which emits microwaves to the conveying mechanism 2 through the opening.

[0046] Along the conveying direction, each microwave generator 3 is used to sequentially emit microwaves onto the polymer particles so that the polymer particles gradually heat up.

[0047] Polymer particles, such as soft TPU, are sensitive to temperature changes. Applying high-power microwaves at once may cause a sudden rise in surface or local area temperature, leading to melting, agglomeration, or side reactions.

[0048] In this embodiment, multiple processing chambers 6 are arranged sequentially along the conveying direction. The microwave generator 3 in each processing chamber 6 can be set with different power or different action time, so that the particles are gradually and steadily heated to the target curing temperature. This "segmented temperature control and gradient heating" strategy can effectively avoid thermal stress concentration and material performance degradation.

[0049] Furthermore, the microwave power of each processing chamber 6 can be independently adjusted to match the heating requirements of different materials. At the same time, the distributed power design reduces the load on individual microwave generators 3, so even if one processing chamber 6 fails, the others can still operate normally, making it suitable for continuous industrial production.

[0050] In some embodiments provided by the present invention, at least one pair of adjacent microwave generators 3 have different powers.

[0051] If all microwave generators have the same power, it may cause localized overheating or underheating. In this embodiment, by rationally allocating the power of each segment, heat loss during the transport process can be compensated, resulting in a more consistent overall temperature. For example, by setting different power levels for adjacent microwave generators, the particles can be heated gradually and steadily during transport, avoiding melting, clumping, or uneven performance caused by sudden high temperatures.

[0052] In some embodiments provided by the present invention, the power of the microwave generator 3 in each processing chamber 6 decreases sequentially along the conveying direction.

[0053] In this embodiment, the polymer particles are at a low temperature in the initial stage of conveying and can withstand high power heating; as the temperature rises, the power is reduced in subsequent stages to avoid the particles from continuing to be strongly heated at high temperatures, effectively preventing melting, adhesion, or agglomeration.

[0054] Furthermore, the initial high-power stage rapidly heats the particles to near the target temperature, while the subsequent low-power stage maintains or finely adjusts the temperature, allowing the particles to smoothly enter the curing stage and facilitating the uniform reaction of NCO and other functional groups. The particles themselves possess thermal inertia; even with reduced microwave power, the temperature will still rise slightly. Lowering the power in the later stage counteracts this delayed heating effect, preventing overall temperature overshoot and resulting in more uniform curing.

[0055] Optionally, there are three processing chambers 6 along the conveying direction. The first microwave generator 3 has a power of 3W / g–5W / g and a processing time of 10s–30s, for example, increasing the temperature of the polymer particles by 30℃–50℃. The second microwave generator 3 has a power of 2W / g–3W / g and a processing time of 10s–30s, for example, increasing the temperature of the polymer particles by 10℃–20℃. The third microwave generator 3 has a power of 0.5W / g–1W / g and a processing time of 30s–60s, for example, increasing the temperature of the polymer particles by 5℃–10℃.

[0056] In this embodiment, the first stage can quickly heat the room temperature particles to near the aging temperature, taking advantage of the material's good heat resistance and high wave absorption efficiency at low temperatures to achieve efficient heating.

[0057] The second stage can be achieved by appropriately adding heat to the already heated particles to avoid overheating, while simultaneously activating the reactivity of polar groups such as NCO.

[0058] The third stage allows for fine-tuning of the temperature and extending the treatment time, ensuring that the particles reach the target ripening temperature uniformly, while reducing thermal stress and preventing surface overheating or clumping. Simultaneously, the main function of the microwave in the third stage is to precisely control the temperature of the polymer particles and homogenize the thermal field, ensuring they enter the hopper at a stable and consistent temperature.

[0059] In some embodiments provided by the present invention, at least a pair of adjacent processing chambers 6 have different spans in the conveying direction.

[0060] In this embodiment, the residence time of polymer particles in the processing chamber 6 is equal to the span of the processing chamber 6 divided by the conveying speed. If the conveying speed is constant, a longer processing chamber 6 naturally corresponds to a longer processing time. Therefore, by designing different spans, the microwave action time of each segment can be flexibly set without changing the operating parameters of the conveying mechanism 2.

[0061] By using a fixed speed and different spans in the processing chamber, the mechanical structure is simpler, the operation is more stable, and the control complexity and failure points are reduced.

[0062] For example, the span of the first processing chamber 6 is smaller than that of the third processing chamber 6. The shorter span of the first processing chamber 6 can prevent the polymer particles from overheating, while the longer span of the third processing chamber 6 can be used to homogenize the temperature and finely control the temperature.

[0063] In some embodiments provided by the present invention, along the conveying direction, the span of the processing chamber 6 closest to the first discharge port 102 is greater than the span of the other processing chambers 6 in the conveying direction. Optionally, the span of the third processing chamber 6 is 2m-3m, the span of the second processing chamber 6 is 0.5m-1m, and the span of the first processing chamber 6 is 0.5m-1m.

[0064] In this embodiment, since the conveying speed is constant, the larger the span, the longer the particles stay in the processing chamber 6. Setting the maximum span in the end processing chamber 6, which is close to the discharge port, means that the polymer particles receive microwave treatment for the longest time in this section.

[0065] Since the granules are already close to the target curing temperature after the initial heating, a low-power, long-duration final treatment is used to avoid temperature overshoot due to thermal inertia. The prolonged, low-intensity microwave treatment helps eliminate minute temperature differences between or within the granules, improving overall thermal uniformity. For soft TPU grades, the residual NCO groups react slowly; extending the final treatment time can activate some of the reaction earlier, reducing the burden on the subsequent hopper and improving curing efficiency.

[0066] In some embodiments provided by the present invention, at least one pair of adjacent microwave generating devices 3 cause different temperature values ​​to be increased in the polymer particles.

[0067] If the temperature rises at the same rate in each stage, the particles may already be in a softened state at high temperatures in the later stages. Continuing to raise the temperature significantly can easily lead to adhesion, clumping, or degradation.

[0068] In this embodiment, differentiated heating can help mitigate this risk. Furthermore, the reaction of residual NCO groups in TPU only proceeds significantly at higher temperatures, but the reaction itself is exothermic and slow. Rapid initial heating activates the system, while subsequent small-scale heating precisely controls and maintains the reaction environment. This satisfies the temperature requirements of the NCO group reaction while avoiding particle melting or performance fluctuations caused by excessive heating, ensuring uniform curing and better conforming to reaction kinetics.

[0069] In some embodiments provided by the present invention, along the conveying direction, the microwave generator 3 near the first feed inlet 101 increases the temperature of the polymer particles by more than the temperature increase of the polymer particles by the other microwave generators 3.

[0070] In this embodiment, when the polymer particles (such as TPU) first enter the curing system, they are at room temperature or a low temperature, the molecular chain movement is weak, the thermal stability is good, and they can withstand the rapid heating brought by high-power microwaves. The significant heating at this stage can efficiently shorten the overall curing time and improve production efficiency.

[0071] The microwave generator 3, located near the feed inlet, increases the temperature of the particles, allowing them to quickly escape the low-temperature zone and shorten the overall heating time. The rear-end device increases the temperature of the particles by a relatively small amount, allowing for focused and precise temperature control to avoid overheating, thus forming a combination of efficient heating and precise temperature achievement.

[0072] For example, soft TPU and other polyol-rich particles have good stability at low temperatures and can withstand significant temperature increases; they are more sensitive to overheating when approaching the curing temperature, and a small temperature difference at the end can gently approach the target temperature, ensuring both the efficiency of the initial heating and preventing local melting or excessive reaction in the later stage, thus ensuring consistent curing.

[0073] In some embodiments provided by the present invention, the polymer particle curing system further includes a baffle assembly.

[0074] The baffle assembly is located on one side of the conveying mechanism 2 and connected to the inner wall of the pretreatment chamber 1. Along the conveying direction of the conveying mechanism 2, the baffle assembly divides the space on one side of the conveying mechanism 2 into at least two processing chambers 6. For example, the baffle assembly includes baffles 7, with at least three baffles 7 arranged sequentially at intervals along the conveying direction, and the space between two adjacent baffles 7 forming a processing chamber 6. The baffles 7 may be made of metal.

[0075] In this embodiment, the space on one side of the conveying mechanism 2 is divided into independent processing chambers 6 by a baffle assembly, so that each microwave energy is relatively independent between the chambers, avoiding mutual interference between microwaves of different power or heating stages, ensuring the stable effectiveness of the power gradient and temperature difference gradient (high at the beginning and low at the end), and guaranteeing the accuracy of the stepped heating. That is, the baffle 7 can reflect or shield microwaves, effectively blocking microwave leakage or interference between adjacent processing chambers 6, ensuring that each segment of microwave energy is accurately applied to the target area, and improving the controllability of heating.

[0076] In addition, the independent processing chamber 6 forms a relatively enclosed radiation space through the baffle 7, which reduces the diffusion of microwave energy to the outside and allows the energy to be more concentrated on the particles on the conveying mechanism 2, especially enhancing the penetration of the particle stacking area and improving heating efficiency and uniformity.

[0077] In some embodiments provided by the present invention, the polymer particle ripening system further includes a temperature detection device 8 and a control system.

[0078] The temperature detection device 8 is located inside the pretreatment chamber 1 and is used to detect the temperature of the polymer particles. For example, the temperature detection device 8 can be an infrared thermometer.

[0079] The control system is connected to the temperature detection device 8 and the microwave generator 3. The control system controls the power of the microwave generator 3 based on the temperature value.

[0080] In this embodiment, devices such as infrared thermometers can capture particle temperature values ​​in real time. The control system dynamically adjusts the power of the microwave generator 3 based on the measured temperature value. For example, the power is increased when the temperature is too low and decreased when the temperature is too high, so as to avoid temperature deviations caused by particle quantity fluctuations and environmental changes, and to ensure that the final curing temperature is accurate and controllable.

[0081] In addition, the system can automatically compensate for minor differences in particle size and initial temperature, ensuring that all particles are cured to a consistent degree without manual intervention. This is especially suitable for temperature-sensitive materials such as soft TPU grades, further reducing the risk of performance fluctuations.

[0082] Furthermore, each processing chamber 6 is equipped with a corresponding temperature detection device 8, and the temperature detection device 8 is connected to the control system.

[0083] In this embodiment, the temperature detection device 8 of each processing chamber 6 provides real-time feedback on the temperature value of the polymer particles in that segment. Based on the measured temperature of each segment, the control system adjusts the power of the microwave generator 3 of the corresponding processing chamber 6 individually, so that each heating process accurately matches the preset requirements and ensures the stability of the stepped heating.

[0084] In addition, the heat absorption state of the particles in different processing chambers 6 may vary due to differences in stacking density, conveying speed, etc. Segmented monitoring can quickly detect abnormal conditions such as high or low temperature in a certain segment, and the power of the corresponding microwave generator 3 can be adjusted in real time through the control system to correct the deviation, prevent local deviation from affecting the overall curing effect, and further improve the curing uniformity.

[0085] In some embodiments provided by the present invention, the silo 4 is provided with an air inlet 403 and an air outlet 404 on its wall.

[0086] The air inlet 403 is used to allow heated airflow to enter the hopper 4. The air outlet 404 is used to discharge the gas inside the hopper 4.

[0087] In this embodiment, the air inlet 403 introduces heated airflow, which can promptly replenish the heat loss of the silo 4 caused by heat dissipation, etc., and ensure that the temperature inside the silo is kept stable at the curing temperature, so as to avoid the particles cooling down and affecting the subsequent curing reaction.

[0088] Optionally, the air inlet 403 is located on the side wall of the silo 4 and near the bottom of the silo 4, and the air outlet 404 is located near the top of the silo 4 or is located on the top of the silo 4.

[0089] Optionally, the air inlet 403 is connected to a heating device 10, which includes an electric heater or a heat exchanger for heating the air. Further, a preheating heat exchanger can be installed upstream of the heating device 10, and the air outlet 404 of the silo 4 is connected to the preheating heat exchanger so that the airflow discharged through the air outlet 404 preheats the air.

[0090] In this embodiment, the electric heater or heat exchanger connected to the air inlet 403 can stably output heated airflow at a set temperature, accurately replenish the heat loss of the silo 4, ensure that the silo is always kept at the curing temperature, and adapt to the heat preservation requirements of different particles.

[0091] In some embodiments provided by the present invention, the conveying mechanism 2 is configured as a conveyor belt, the first feed inlet 101 is located above the conveyor belt, and a guide plate 11 is provided at the first discharge outlet 102. One end of the guide plate 11 extends to the discharge end of the conveyor belt and receives the polymer particles conveyed by the conveyor belt, and the other end of the guide plate 11 extends to the first discharge outlet 102.

[0092] In this embodiment, the conveyor belt can smoothly transport polymer particles from the first feed inlet 101 to the discharge end, ensuring that the particles move along a set path in the pretreatment chamber 1 and receive microwave heating from each treatment chamber 6 evenly, adapting to the rhythm of continuous industrial production.

[0093] In addition, the guide plate 11 at the first discharge port 102 is connected to the discharge end of the conveyor belt at one end and leads to the first discharge port 102 at the other end. It can smoothly guide the particles conveyed by the conveyor belt to the hopper 4, avoid the particles from accumulating, scattering or remaining at the discharge port, reduce material loss, and at the same time ensure the continuity of particles entering the hopper 4.

[0094] In some embodiments provided by the present invention, the top of the hopper 4 is provided with a second inlet 401, which is connected to the first outlet 102. The bottom of the hopper 4 is configured as a conical structure, and the bottom end of the conical structure forms the second outlet 402.

[0095] In this embodiment, the second feed inlet 401 at the top is directly connected to the first discharge outlet 102 of the pretreatment chamber 1, allowing the particles heated by microwave to enter the silo 4 quickly and without leakage, thus achieving a seamless connection between pretreatment and heat preservation and curing.

[0096] In addition, the bottom conical structure can use gravity to guide the particles to gather at the second discharge port 402 at the bottom, avoiding particles from remaining and accumulating in the corners of the silo, ensuring smooth discharge and reducing material loss.

[0097] In some embodiments of the present invention, the stirring mechanism 5 includes stirring blades and a rotating device. The stirring blades are rotatably disposed within the hopper 4, and the rotating device is disposed at the top of the hopper 4 and is drively connected to the blades. The rotating device is used to drive the blades to rotate. For example, the rotating device is an electric motor or a hydraulic motor.

[0098] In this embodiment, the rotating device drives the stirring blades to rotate inside the hopper 4, which continuously agitates the polymer particles inside the hopper, ensuring that all particles can be fully matured in a stable and heat-insulated environment, reducing performance differences.

[0099] Furthermore, the rotating device is located at the top of the hopper 4, without occupying the bottom discharge space, and does not conflict with the discharge design of the conical bottom. The stirring blades can extend to the lower part of the hopper 4, covering the main particle accumulation area, ensuring maximum turning range and further guaranteeing consistent maturation.

[0100] In some embodiments provided by the present invention, the polymer particle maturation system further includes a screening device 9, the outlet of which is connected to the first feed inlet 101.

[0101] In this embodiment, the screening device 9 can pre-filter impurities, clumps, or particles exceeding the size limit in the polymer particles, allowing only qualified particles to enter the pretreatment chamber 1, thus avoiding unqualified materials from affecting the uniformity of microwave heating and ensuring the subsequent curing effect and the final performance of the particles from the source.

[0102] Furthermore, the outlet of the screening device 9 is directly connected to the first feed inlet 101, eliminating the need for additional transfer links and achieving seamless integration of screening and maturation without affecting production efficiency. Simultaneously, the screen specifications can be flexibly changed according to the particle size requirements of the maturation process, adapting to the pretreatment needs of different materials and enhancing the system's versatility.

[0103] The present invention also provides a specific embodiment in which the above system is used to cure and dry 70A soft TPU. Four curing temperatures are set as examples. The moisture content, melt index fluctuation value (multiple time points sampling), and agglomeration are compared with the traditional curing and drying method. The comparison data are shown in Table 1.

[0104] Table 1

[0105] The data in Table 1 shows that the embodiments of the present invention can solve the clumping problem while achieving the same drying effect, and the material properties at each point in the silo 4 are uniform and stable.

[0106] This invention also provides a method for ripening polymer particles.

[0107] Specifically, the polymer particle ripening method is used to ripen polymer particles containing polar groups. For example, the polymer particle ripening method can be implemented based on the polymer particle ripening system described above.

[0108] The method for ripening polymer particles includes steps S100-S200.

[0109] In step S100, the polymer particles are subjected to microwave pretreatment to heat them to the ripening temperature using microwaves.

[0110] Specifically, microwaves can be emitted to polymer particles using microwave generator 3. The microwave energy can directly act on the polar groups inside the polymer particles, and the high-speed vibration of polar molecules generates heat to raise the temperature of the polymer particles.

[0111] Step S200: The polymer particles that have reached the curing temperature are introduced into the silo 4, hot air is introduced into the silo 4 to maintain the curing temperature of the polymer particles, and the polymer particles are stirred.

[0112] Specifically, the microwave-treated polymer particles can be introduced into the hopper 4, and a heated airflow can be introduced into the hopper 4 to maintain the curing temperature inside the hopper 4. At the same time, the polymer particles are stirred by the stirring mechanism 5 installed in the hopper 4.

[0113] In this embodiment, microwave heating is employed. Microwave energy directly acts on the polar groups inside the polymer particles, such as the NCO groups in TPU. Heat is generated by the high-speed vibration of polar molecules, eliminating the need for heat conduction or convection, thus achieving simultaneous heating inside and outside the particles. The microwave generator 3 is oriented towards the conveying mechanism 2. During the conveying process, the particles move, preventing uneven heating and ensuring that each polymer particle receives microwave energy uniformly, ultimately reaching a consistent ripening temperature.

[0114] Furthermore, by utilizing the uniformity of microwave heating, the reaction rate of NCO groups can be kept consistent, and the degree of ripening can be highly uniform, thus avoiding performance fluctuations caused by uneven ripening from the root. This is especially suitable for polymer materials that require high ripening consistency.

[0115] Furthermore, microwave heating rapidly raises the particles to the curing temperature, and its heating rate is much higher than that of hot air heating, thus shortening the heating time. The hopper 4 receives the heated particles and, while maintaining the curing temperature, continuously stirs them through the stirring mechanism 5. This ensures that the particles complete the subsequent curing reaction in a constant temperature environment and further guarantees uniform heating.

[0116] In addition, as long as the microwave power and conveying speed are set to match, the particles can be precisely heated to the ripening temperature. The heated particles do not need to be heated or dried in the hopper 4 with air that is higher than the ripening temperature. There is no premise of local overheating, which can fundamentally prevent the particles from melting and sticking together in the hopper.

[0117] Microwaves rapidly heat polymer particles to their ripening temperature, rather than completing the entire ripening reaction. Microwave heating is fast (polar molecules generate heat directly with no heat transfer loss), requiring only a shorter transport path to achieve precise particle heating. This avoids the need to lengthen the transport mechanism 2 to extend the ripening time, thus controlling the floor space of the pretreatment chamber 1 from the outset.

[0118] In summary, the polymer particle curing system provided in this application is particularly suitable for curing soft-grade TPU with a Shore hardness of 60A-95A.

[0119] In some embodiments provided by the present invention, the polymer particles are subjected to at least two microwave pretreatments to gradually heat the polymer particles.

[0120] In this embodiment, gradual heating is achieved through at least two microwave treatments. Each microwave treatment can be set with different power or different duration, allowing the particles to gradually and steadily heat up to the target ripening temperature. This "segmented temperature control and gradient heating" strategy can effectively avoid thermal stress concentration and material performance degradation.

[0121] In some embodiments provided by the present invention, the power of each microwave preprocessing step is gradually reduced.

[0122] In this embodiment, the polymer particles are at a low temperature in the initial stage of conveying and can withstand high power heating; as the temperature rises, the power is reduced in subsequent stages to avoid the particles from continuing to be strongly heated at high temperatures, effectively preventing melting, adhesion, or agglomeration.

[0123] Furthermore, the initial high-power stage rapidly heats the particles to near the target temperature, while the subsequent low-power stage maintains or finely adjusts the temperature, allowing the particles to smoothly enter the curing stage and facilitating the uniform reaction of NCO and other functional groups. The particles themselves possess thermal inertia; even with reduced microwave power, the temperature will still rise slightly. Lowering the power in the later stage counteracts this delayed heating effect, preventing overall temperature overshoot and resulting in more uniform curing.

[0124] In some embodiments provided by the present invention, the initial microwave pretreatment increases the temperature of the polymer particles by a greater value than the subsequent microwave pretreatments.

[0125] In this embodiment, the polymer particles (such as TPU) are at room temperature or a low temperature before pretreatment. The molecular chain movement is weak and the thermal stability is good. They can withstand the rapid heating brought by high-power microwaves. The large heating at this stage can efficiently shorten the overall curing time and improve production efficiency.

[0126] The first microwave pretreatment increases the temperature of the particles more significantly, allowing them to quickly escape the low-temperature zone and shorten the overall heating time. Subsequent microwave pretreatments increase the temperature of the particles less significantly, allowing for focused and precise temperature control to avoid overheating, thus creating a combination of efficient heating and precise temperature achievement.

[0127] For example, soft TPU and other polyol-rich particles have good stability at low temperatures and can withstand significant temperature increases; they are more sensitive to overheating when approaching the curing temperature, and a small temperature difference at the end can gently approach the target temperature, ensuring both the efficiency of the initial heating and preventing local melting or excessive reaction in the later stage, thus ensuring consistent curing.

[0128] In some embodiments provided by the present invention, the duration of the final microwave preprocessing is longer than the duration of the remaining microwave preprocessing.

[0129] In this embodiment, since the particles are already close to the target curing temperature after the initial heating, a low-power, long-duration process is used at the end to avoid temperature overshoot due to thermal inertia. The prolonged low-intensity microwave treatment helps eliminate minute temperature differences between or within particles, improving overall thermal uniformity. For example, for soft TPU grades, the residual NCO groups react slowly; extending the final treatment time can activate some of the reaction earlier, reducing the burden on the subsequent hopper 4 and improving curing efficiency.

[0130] Although embodiments of the invention have been described in conjunction with the accompanying drawings, those skilled in the art can make various modifications and variations without departing from the spirit and scope of the invention, and all such modifications and variations fall within the scope defined by the appended claims.

Claims

1. A polymer particle ripening system, characterized in that, Used for ripening polymer particles containing polar groups, including: The pretreatment chamber (1) is provided with a first feed inlet (101) and a first discharge outlet (102); A conveying mechanism (2) is provided in the pretreatment chamber (1) and is used to convey the polymer particles between the first feed inlet (101) and the first discharge outlet (102); A microwave generator (3) is located inside the pretreatment chamber (1) and on one side of the conveying mechanism (2). The microwave generator (3) faces the conveying mechanism (2) and is used to emit microwaves to the conveying mechanism (2) to heat the polymer particles to the ripening temperature. The hopper (4) is connected to the first discharge port (102) to receive the polymer particles, and the hopper (4) is used to maintain the ripening temperature. A stirring mechanism (5) is located inside the silo (4) and is used to stir the polymer particles.

2. The polymer particle ripening system according to claim 1, characterized in that, The pretreatment chamber (1) is provided with at least two processing chambers (6). Along the conveying direction of the conveying mechanism (2), at least two processing chambers (6) are arranged sequentially on one side of the conveying mechanism (2), and each processing chamber (6) is provided with the microwave generator (3) and an opening facing the conveying mechanism (2). Along the conveying direction, each of the microwave generating devices (3) is used to emit microwaves to the polymer particles in sequence so that the polymer particles gradually heat up.

3. The polymer particle ripening system according to claim 2, characterized in that, Along the conveying direction, the power of the microwave generator (3) in each of the processing chambers (6) decreases sequentially; And / or, at least one pair of adjacent microwave generators (3) have different powers.

4. The polymer particle ripening system according to claim 2, characterized in that, Along the conveying direction, the span of the processing chamber (6) closest to the first discharge port (102) in the conveying direction is greater than the span of the other processing chambers (6) in the conveying direction; And / or, at least one pair of adjacent processing chambers (6) have different spans in the conveying direction.

5. The polymer particle ripening system according to claim 2, characterized in that, Along the conveying direction, the microwave generator (3) near the first feed inlet (101) causes the polymer particles to increase in temperature by a greater value than the other microwave generators (3) cause the polymer particles to increase in temperature. And / or, at least one pair of adjacent microwave generating devices (3) cause the polymer particles to increase at different temperatures.

6. The polymer particle ripening system according to claim 1, characterized in that, The polymer particle ripening system also includes: A temperature detection device (8) is installed in the pretreatment chamber (1) and is used to detect the temperature value of the polymer particles; The control system is connected to the temperature detection device (8) and the microwave generator (3), and the control system controls the power of the microwave generator (3) based on the temperature value.

7. The polymer particle ripening system according to claim 1, characterized in that, The silo (4) has the following features on its walls: Air inlet (403) is used to allow heated airflow to enter the silo (4); The air outlet (404) is used to discharge the gas in the silo (4).

8. The polymer particle ripening system according to claim 1, characterized in that, The polymer particle maturation system also includes a screening device (9), the outlet of which is connected to the first feed inlet (101).

9. A method for ripening polymer particles, characterized in that, Used for ripening polymer particles containing polar groups, including: The polymer particles are subjected to microwave pretreatment to heat them to a ripening temperature using microwaves. The polymer particles that have reached the ripening temperature are introduced into the silo (4), hot air is introduced into the silo (4) to keep the polymer particles at the ripening temperature, and the polymer particles are stirred.

10. The method for ripening polymer particles according to claim 9, characterized in that, The polymer particles are subjected to at least two microwave pretreatments to gradually heat them, wherein: The power of each microwave preprocessing step gradually decreases; And / or, the initial microwave pretreatment increases the temperature of the polymer particles by a greater value than the subsequent microwave pretreatments. And / or, the duration of the last microwave preprocessing is longer than the duration of the remaining microwave preprocessing.

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