Pure physical spheroidizing device for polymer powder

Abstract

The invention provides a pure physical spheroidizing device for polymer powder, and belongs to the field of polymer microsphere preparation. The pure physical spheroidizing device comprises a feeding system, a spheroidizing system, a circulating cooling system and a microsphere grading and collecting system, the feeding system comprises a feeding-preheating synchronization unit, a high-speed jet flow powder spraying unit and a solid-gas sheath flow guide unit which are connected in sequence; the spheroidizing system comprises a slender spheroidizing furnace and a cooling hopper connected with the tail end of the spheroidizing furnace; a shower head type dispersion mechanism communicated with an outlet of the solid-gas sheath flow guide unit is suspended at the top end of the spheroidizing furnace; according to the temperature decreasing setting, the spheroidizing furnace is divided into at least three sections in the axial direction. According to the device disclosed by the invention, the feeding system at the front end of the spheroidizing furnace realizes efficient transportation and synchronous heating of powder through a gas-solid synergistic effect and a hot air preheating coupling mechanism, and the uniformity, the stability and the flowability of polymer microspheres are effectively improved by combining shower head type dispersed feeding, segmented temperature control and rapid cooling setting of the spheroidizing system.

Description

Technical Field

[0001] The invention belongs to the technical field of polymer microsphere preparation, and in particular relates to a purely physical spheroidization device for polymer powders. Background Art

[0002] Polymer microspheres are tiny spherical particles made of polymer materials. With their unique spherical structure and excellent functional properties, they have become an indispensable core material in high-end technology products, especially in the fields of biomedicine, 3D printing, chemical catalysis, etc., showing great application potential. For example, in the field of medical aesthetics, the spherical shape and smooth surface of microspheres can reduce the friction between cosmetics and skin, making application more even and smoother. At the same time, polymer microspheres can also fill depressions, thereby restoring the smoothness and glossiness of the skin. In the pharmaceutical field, microspheres are often used as drug carriers to encapsulate and protect drugs, and slowly release drugs at the site of administration in the body, extending the half-life while reducing its toxic side effects. In the field of 3D printing, microspheres with regular geometric shapes can significantly improve the fluidity of powders, ensure the uniformity of powder spreading during the 3D printing process, and reduce interlayer gaps and printing defects. In the field of chemical catalysis, microspheres with regular surfaces can form a uniform active site distribution interface, reduce local concentration differences of reactants, and improve the efficiency of catalytic reactions.

[0003] Currently, the main methods for preparing polymer microspheres are solvent method and mechanical method. Among them, the solvent method is to dissolve the polymer or monomer in an organic solvent, and then remove the solvent by appropriate methods to form a polymer powder. However, this method involves the use of organic solvents, and the microspheres prepared cannot meet biosafety requirements. At the same time, it is impossible to prepare composite powders and the particle size is difficult to meet 3D printing requirements. The mechanical method is to subject the polymer material to high-speed, high-frequency impact or grinding to continuously refine the particles, and obtain polymer powder after crushing and screening. Although this method does not involve solvents, the prepared polymer powder has an irregular shape. Summary of the Invention

[0004] In view of this, the object of the present invention is to provide a purely physical spheroidization device for polymer powders, aiming to solve the problem of irregular powders prepared by mechanical methods in the background art.

[0005] To achieve the above-mentioned purpose, the present invention has developed a purely physical spheroidization device for polymer powders, which includes a feeding system, a spheroidization system, a circulating cooling system and a microsphere classification and collection system; the feeding system, the spheroidization system and the microsphere classification and collection system are connected in sequence;

[0006] The feeding system is used to preheat the polymer powder and feed it to the spheroidization system, which includes a feeding-preheating synchronization unit, a high-speed jet powder spraying unit and a solid-gas sheath flow guide unit connected in sequence;

[0007] The spheroidization system uses high-temperature spheroidization shaping technology to melt irregular polymer powder in a flowing state and then cool it to obtain polymer microspheres. The spheroidization system includes a spheroidization furnace and a cooling hopper connected to the end of the spheroidization furnace. A shower-type dispersion mechanism connected to the outlet of the solid-gas sheath flow guide unit is suspended at the top of the spheroidization furnace. The spheroidization furnace is divided into at least three sections along the axial direction according to the temperature reduction setting.

[0008] The circulating cooling system uses cryogenic fluid as a medium to regulate and cool the temperature inside the spheroidizing system.

[0009] The microsphere classification and collection system is used to classify and collect polymer microspheres through multi-stage particle capture;

[0010] The microsphere classification and collection system includes a collection bin connected to the outlet of the cooling hopper and a cyclone separation mechanism connected to the discharge end of the collection bin;

[0011] The collection chamber is internally provided with at least two layers of screens with different apertures for collecting the polymer microspheres in a graded manner.

[0012] Furthermore, the spheroidization furnace is provided with an adaptive temperature control unit, which includes a thermocouple array. The thermocouple array is used as a temperature sensor to monitor the temperature of each section in the spheroidization furnace in real time and provide feedback. The heating power is dynamically adjusted according to the melting point of the powder and the fluidization requirements, thereby achieving precise control of the temperature field uniformity and the spheroidization process.

[0013] A temperature sensor is provided in the cooling bucket.

[0014] Furthermore, the feeding-preheating synchronization unit includes a horizontal solid-gas mixing drum, a vertical powder feeding mechanism connected to the solid-gas mixing drum, a hot air drainage mechanism for conveying hot air to the solid-gas mixing drum, and a feeding pipe for conveying the solid-gas mixture to the high-speed jet powder spraying unit;

[0015] A thermocouple sensor is provided at the junction of the solid-gas mixing cylinder and the hot air drainage mechanism for monitoring the temperature of the hot air flow; and an electric heating wire is installed on the solid-gas mixing cylinder.

[0016] Furthermore, the high-speed jet powder spraying unit includes a jet power device connected to the end of the feed pipe, a porous nozzle and a feed pipe connected to the outlet of the jet power device, and the end of the feed pipe extends to the inlet of the solid-gas sheath flow guide unit.

[0017] Furthermore, the solid-gas sheath flow guide unit is connected to the inlet end of the spheroidization system, and the solid-gas sheath flow guide unit includes a guide box with an upper cylinder and a lower cone structure, and a feed nozzle connected to the end of the feed pipe is suspended in the middle of the top of the guide box;

[0018] At least two groups of evenly distributed air guide heads are arranged around the periphery of the feed nozzle, and the air guide heads are connected to an external blower to concentrate the polymer powder sprayed from the feed nozzle to the middle;

[0019] At least two groups of flow stabilizing mesh plates are arranged in the flow guide box, and the apertures of the flow stabilizing mesh plates of each group decrease in sequence from top to bottom.

[0020] Furthermore, the ratio of the inner diameter of the spheroidizing furnace to the inner diameter of the cooling hopper outlet is 5 to 15:1; and the length of the spheroidizing furnace is not less than 3 meters;

[0021] The shower-style dispersion mechanism includes a high-temperature resistant stainless steel nozzle and a microporous dispersion plate. The microporous array disperses the powder stream into a cluster of fine particles, increasing the contact area with the hot air flow and adjusting the air flow pressure to optimize the initial distribution of the powder in the furnace, avoid agglomeration, and improve the fluidization effect.

[0022] Furthermore, the spheroidizing furnace is also provided with a visual real-time monitoring device, which is embeddedly installed on the outer wall of the end of the spheroidizing furnace; the visual real-time monitoring device includes a high-temperature resistant optical window and a high-speed camera system.

[0023] Furthermore, the circulating cooling system includes cooling pipes surrounding the outer walls of the spheroidizing furnace and the cooling hopper, a cooling tank for storing cooling fluid, a liquid inlet mechanism for transporting the cooling fluid to different areas of the cooling pipes, and a drain pipe for discharging the cooling fluid after absorbing heat.

[0024] Furthermore, the length-to-diameter ratio of the collection chamber is designed to be 2 to 4:1;

[0025] The collection bin includes a bin cylinder with at least two layers of screens with different apertures, and a negative pressure suction mechanism that transports the graded and collected polymer microspheres to the cyclone separation mechanism; the screens at each layer are designed to have apertures that decrease along the airflow direction.

[0026] Compared with the prior art, the present invention has the following beneficial effects:

[0027] 1. The feeding system at the front end of the spheroidizing furnace of the present invention is configured as a composite structure of a feeding-preheating synchronization unit, a high-speed jet powder spraying unit, and a solid-gas sheath flow guide unit. Through the gas-solid synergy and the hot air preheating coupling mechanism, efficient powder transportation and synchronous heating are achieved. Combined with the shower-like dispersed feeding, segmented temperature control, and rapid cooling settings of the spheroidizing system, the sphericity, uniformity, and fluidity of the polymer microspheres are effectively improved. Specifically, the sphericity is higher than 0.9, the angle of repose is less than 30°, and the particle size is consistent.

[0028] 2. The device of the present invention is equipped with a circulating cooling system. Based on the principle of heat transfer and thermal balance of low-temperature fluid, the cooling fluid is used as the medium to achieve precise temperature control and rapid cooling inside the entire spheroidization system, which is conducive to the precise control of the spheroidization process.

[0029] 3. The spheroidizing furnace used in the present invention is suitable for thermoplastic polymer materials with a melting point below 350°C and can be used for large-scale production with a production capacity of 1 to 10 kg / h / unit.

[0030] 4. The device of the present invention is not only applicable to single polymer materials, but can also compound functional materials with polymers to form uniform, regular, and highly spherical composite polymer microsphere powders.

[0031] 5. The device of the present invention can be used for spheroidization of polymer powders in the fields of biomedicine, 3D printing, chemical catalysis, etc. It has a wide range of applications and excellent product effects.

[0032] 6. The physical and chemical properties of the powder do not change significantly before and after spheroidization in the device of the present invention, and it has excellent biocompatibility. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 It is a structural schematic diagram of the spheroidizing device of the present invention;

[0034] Figure 2 Schematic diagram of the external three-dimensional structure, internal structure, and top view structure of the flow stabilizing mesh plate of the solid-gas sheath flow guide unit of the present invention;

[0035] Figure 3 Schematic diagram of the internal structure of the solid-gas mixing cylinder in the present invention;

[0036] Figure 4 This is a schematic diagram of the internal structure of the spheroidizing furnace of the present invention;

[0037] Figure 5 This is a schematic diagram of the internal structure of the spheroidizing furnace of the present invention from a top view;

[0038] Figure 6 Schematic diagram of the external three-dimensional structure of the shower-type dispersion mechanism and the microporous dispersion disk in the spheroidizing furnace of the present invention when viewed from above;

[0039] Figure 7 Schematic diagram of the external three-dimensional structure of the visual real-time monitoring device of the present invention;

[0040] Figure 8 This is a schematic diagram of the internal structure of the collection bin of the present invention from a top view.

[0041] Illustration:

[0042] 110 - feeding-preheating synchronization unit, 111 - hot air drainage mechanism, 112 - powder feeding mechanism, 113 - solid-gas mixing cylinder, 114 - feeding pipe, 115 - electric heating wire, 116 - thermocouple sensor;

[0043] 120- high-speed jet powder spraying unit, 121- jet power equipment, 122- multi-hole nozzle, 123- feed pipe;

[0044] 130- solid-gas sheath flow guide unit, 131- feed nozzle, 132- flow guide box, 133- gas guide head, 134- flow stabilizing screen;

[0045] 210-Spheroidizing furnace, 211-Shower-type dispersion mechanism, 2111-High-temperature-resistant stainless steel nozzle, 2112-Microporous dispersion disk, 212-Heating element, 213-Thermocouple array, 220-Visual real-time monitoring device, 221-Optical window, 222-High-speed camera system, 230-Cooling bucket, 231-Temperature sensor;

[0046] 310-cooling tank, 320-liquid inlet mechanism, 330-liquid discharge pipe, 340-cooling pipe;

[0047] 410 - collection bin, 411 - bin tube, 412 - screen, 413 - negative pressure suction mechanism, 420 - cyclone separation mechanism. DETAILED DESCRIPTION

[0048] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific implementation cases described herein are only used to explain the present invention and are not intended to limit the present invention.

[0049] Example 1

[0050] like Figures 1 to 8 As shown, a purely physical spheroidization device for polymer powders includes a feeding system, a spheroidization system, a circulating cooling system, and a microsphere classification and collection system.

[0051] The feeding system is used to preheat the polymer powder and feed it into the spheroidization system at high speed and uniformly. The feeding system is based on the principles of particle fluid mechanics and heat conduction, and realizes efficient powder transportation and synchronous heating through the gas-solid synergy and hot air preheating coupling mechanism; the feeding system includes a feeding-preheating synchronization unit 110, a high-speed jet powder spraying unit 120 and a solid-gas sheath flow guide unit 130 connected in sequence.

[0052] The feed-preheat synchronization unit 110 ensures that the polymer powder material is simultaneously preheated to the set temperature during the feeding process, while also improving heating uniformity through the use of hot air flow. It comprises a horizontal solid-gas mixing drum 113, a vertical powder feeding mechanism 112 connected to the solid-gas mixing drum 113, a hot air drainage mechanism 111 that delivers hot air to the solid-gas mixing drum 113, and a feed pipe 114 that conveys the solid-gas mixture to the high-speed jet powder spraying unit 120. The feed-preheat synchronization unit 110 achieves feed-preheat coupling. The heat source for preheating is the hot air flow transported by the hot air drainage mechanism 111. The hot air drainage mechanism 111 adopts a heater, a fan, a pipe, a valve, etc., which transports the air flow of a preset temperature to the solid-gas mixing cylinder 113. Due to the heat loss of the hot air drainage mechanism 111 during the transportation process, the preheating temperature deviates from the actual requirement. For this reason, a thermocouple sensor 116 is set at the connection between the solid-gas mixing cylinder 113 and the hot air drainage mechanism 111 to monitor the temperature of the hot air flow; an electric heating wire 115 is installed on the solid-gas mixing cylinder 113 to make up for the heat loss and heat the hot air flow to the actual required preheating temperature. The powder feeding mechanism 112 can be adjusted according to actual needs. If a single polymer powder is used, it can be directly fed through a pump or a conveying device; if it is a composite of an inorganic functional filler and a polymer material, the powder feeding mechanism 112 includes an extrusion mechanism and a freezing mechanism. Specifically, the polymer particles and the functional filler are first compounded using the melt extrusion technology of the extrusion mechanism, and uniformly dispersed polymer particles are obtained through high-temperature melting and shearing. The polymer particles are then processed through the low-temperature crushing method of the freezing mechanism, that is, the material is brittled and then crushed using liquid nitrogen freezing to obtain small-sized and irregular polymer powder.

[0053] The high-speed jet powder spraying unit 120 includes a fluidic device 121 connected to the end of the feed tube 114, a porous nozzle 122 connected to the outlet of the fluidic device 121, and a feed pipe 123. The end of the feed pipe 123 extends to the inlet of the solid-gas sheath flow guide unit 130. The fluidic device 121 uses a high-pressure centrifugal blower or ejector, and utilizes the porous nozzle 122 to generate a uniform high-speed jet, which propels the polymer powder material within the feed pipe 123 for stable transportation. The high-speed jet powder spraying unit 120 is equipped with a flow control valve and a pressure sensor (not labeled) to precisely control the airflow speed and pressure, ensuring efficient and consistent transportation.

[0054] The solid-gas sheath flow guide unit 130 is connected to the inlet end of the spheroidization system. The solid-gas sheath flow guide unit 130 includes a guide box 132 with an upper tube and lower cone structure. A feed nozzle 131 connected to the end of the feeding pipe 123 is suspended in the middle of the top of the guide box 132. At least two groups of evenly distributed air guide heads 133 are arranged around the outer periphery of the feed nozzle 131. The air guide heads 133 are connected to an external fan to concentrate the polymer powder sprayed into the feed nozzle 131 to the middle part; at least two groups of flow stabilizing mesh plates 134 are arranged in the guide box 132, and the aperture of the flow stabilizing mesh plates 134 decreases from top to bottom; the conical design of the lower part of the guide box 132 is combined with the auxiliary airflow of the air guide head 133 to form a sheath flow effect, which wraps and stabilizes the powder flow beam and prevents the powder from sticking to the wall.

[0055] Based on the principle of minimum energy for incompatible systems, the spheroidization system utilizes high-temperature spheroidization shaping technology under flow conditions to transform irregular powders into spherical shapes with minimal surface free energy while in a molten state, thereby producing polymer microspheres. The spheroidization system comprises an elongated spheroidization furnace 210 and a cooling hopper 230 connected to the end of the spheroidization furnace 210. The spheroidization furnace 210 is constructed of high-temperature resistant ceramic composite materials, and a shower-like dispersion mechanism 211 is suspended from its top, connected to the outlet of the solid-gas sheath flow guide unit 130. A heating element 212 is installed within the spheroidization furnace 210 to heat the interior. The spheroidization furnace 210 is divided into at least three sections along the axial direction according to different temperatures. A thermocouple array 213 is installed within the spheroidization furnace 210 to provide real-time temperature monitoring and feedback for each section. A temperature sensor 231 is also installed within the cooling hopper 230 to monitor the internal temperature. The cooling hopper 230 sets the heating temperature in sections based on the powder flow direction, with the temperature gradually decreasing from top to bottom. The final section is a heat-insulating section, where radiant heating maintains the stability of the molten powder and gradually transforms it into a spherical shape during the fluidization process. The molten powder completes its cooling in the cooling hopper 230. The present invention also includes an automatic control system that adjusts the output of the heating element 212 based on real-time temperature feedback from the thermocouple array 212 and actual needs, thereby controlling the temperature within the spheroidization furnace 210. The ratio of the inner diameter of the spheroidization furnace 210 to the inner diameter of the cooling hopper 230 outlet is 5 to 15:1, preferably 10:1. The length of the spheroidization furnace 210 is no less than 3 meters. The limited size of the spheroidization furnace 210 ensures the residence time of the powder during the fluidization process and the efficiency of thermal coupling, allowing the molten powder to fully transform into a spherical shape and improving the spheroidization effect.

[0056] The shower-type dispersion mechanism 211 includes a high-temperature resistant stainless steel nozzle 2111 and a microporous dispersion disk 2112. The microporous array of the microporous dispersion disk is used to disperse the powder flow into a group of fine particles, thereby increasing the contact area with the hot air. At the same time, by adjusting the airflow pressure of the high-temperature resistant stainless steel nozzle, the initial distribution state of the powder in the furnace is optimized, the powder agglomeration phenomenon is reduced, and the fluidization effect is improved.

[0057] The spheroidizing furnace 210 is also equipped with a visual real-time monitoring device 220, which is embedded in the outer wall at the end of the spheroidizing furnace 210. The visual real-time monitoring device 220 includes a high-temperature resistant optical window 221 and a high-speed camera system 222. The optical window 221 is embedded in the side wall of the furnace. In conjunction with an external light source and the high-speed camera system 222, it records the morphological evolution of the powder in the molten state in real time, facilitating spheroidization process optimization and quality assessment.

[0058] The circulating cooling system, based on the principles of heat transfer and thermal equilibrium using a low-temperature fluid, utilizes a circulating cooling medium (cooling fluid) to achieve precise temperature control and rapid cooling throughout the entire spheroidization system. The system injects cooling fluid into different sections of the spheroidization furnace 210 and the cooling hopper 230 in stages, dynamically balancing cooling output to ensure a uniform temperature field. A thermocouple array 212 and temperature sensor 231 record the temperature distribution of the spheroidization furnace 210 and the cooling hopper 230 in real time to control the output of the circulating cooling system. The circulating cooling system includes cooling pipes 340 surrounding the outer walls of the spheroidization furnace 210 and the cooling hopper 230; a cooling tank 310 for storing the cooling fluid; an inlet mechanism 320 for delivering the cooling fluid to the different sections of the cooling pipes 340; and a discharge pipe 330 for discharging the heat-absorbing cooling fluid. After absorbing heat from the spheroidization furnace 210 and the cooling hopper 230, the heat-absorbing liquid is discharged to an external radiator for heat recovery and reuse. The liquid inlet mechanism 320 includes common equipment such as pipes, pumps, and valves, and is used to control the start and stop, as well as the flow rate, of the circulating cooling system's delivery of cooling fluid to different areas of the spheroidizing furnace 210 and the cooling hopper 230. In practice, the circulating cooling system can be activated during spheroidizing to maintain the interior of the spheroidizing furnace 210 at a suitable operating temperature. Activating the circulating cooling system during the cooling process allows for rapid cooling in the cooling hopper 230 area after spheroidizing. The liquid volume, flow rate, and temperature can be adjusted according to operational needs. Liquids have better thermal conductivity than air, and the circulating cooling system can more efficiently transfer heat away from the heat source, achieving rapid cooling, higher heat dissipation efficiency, lower noise, and uniform temperature distribution.

[0059] The microsphere classification and collection system, based on the principles of gas-solid separation and particle classification, employs multi-stage particle collection technology to achieve efficient classification and collection of spheroidized microspheres. The microsphere classification and collection system comprises a collection chamber 410 connected to the outlet of the cooling hopper 230 and a cyclone separation mechanism 420 connected to the discharge end of the collection chamber 410. The collection chamber 410 is designed with an aspect ratio of 2 to 4:1, preferably 3:1, to optimize airflow distribution and particle settling efficiency, ensuring a smooth and efficient classification and collection process for the spheroidized microspheres. The collection chamber 410 comprises a silo 411 containing at least two layers of screens 412 of varying apertures. The apertures of the screens 412 are adjusted based on the desired product. The polymer microspheres are initially classified and collected using the screens 412, which are then transported to the cyclone separation mechanism 420 via a negative pressure suction mechanism 413. The apertures of each layer of screens 412 decrease in diameter along the airflow direction, and the aperture size is adjusted based on the desired microsphere production. In a specific implementation, the cyclone separation mechanism 420 includes a centrifugal cyclone and a collector at the bottom. Small particle microspheres that meet the size requirements are separated into the collector through high-speed rotating airflow, and an air lock discharge valve is used to achieve continuous operation and stable particle output. Large particle microspheres are captured and processed separately.

[0060] Example 2

[0061] This embodiment uses the device of Example 1 to prepare polymer microspheres for use in the medical aesthetics field, with a particle size range of 10 μm to 50 μm.

[0062] The steps of this embodiment are as follows:

[0063] S1. The preheating temperature of the feed-preheating synchronization unit 110 is set to 100° C. The hot air guide mechanism 111 conveys the hot air flow to the solid-gas mixing drum 113. The thermocouple sensor 116 and the electric heating wire 115 control the air flow temperature entering the solid-gas mixing drum 113 to 100° C.; irregularly shaped left-handed polylactic acid particles (molecular weight range is 120,000, viscosity range is 0.6 dL / g, purity is 99%, and particle size is 40 μm to 80 μm) are introduced into the solid-gas mixing drum 113 through the powder feeding mechanism 112, and coupled with the 100° C. hot air flow to form a solid-gas mixture; the high-speed jet powder spraying unit 120 stably transports the solid-gas mixture to the solid-gas sheath flow guide unit 130. Under the action of the auxiliary air flow of the air guide head 133 and the two sets of flow stabilizing screens 134, the left-handed polylactic acid particles form a sheath flow effect in the guide box 132, and are discharged from the middle into the spheroidization system in a centralized manner;

[0064] S2. The shower-type dispersion mechanism 211 disperses the preheated L-polylactic acid particles into fine particle groups and enters the spheroidizing furnace 210 (7 meters in length, with a ratio of its inner diameter to the inner diameter of the outlet of the receiving hopper 230 of 10:1). The spheroidizing furnace 210 is divided into three different temperature zones (190°C, 170°C, and 140°C) from top to bottom according to temperature. The temperature of the cooling hopper 230 zone is controlled to 70°C through a circulating cooling system (using cold water at 0°C to 10°C as the cooling fluid). The L-polylactic acid particles melt in the spheroidizing furnace 210 and fall into the cooling hopper 230 for cooling, thereby forming L-polylactic acid microspheres.

[0065] S3. After being discharged from the cooling hopper 230, the L-polylactic acid microspheres enter the collection bin 410 (with a length-to-diameter ratio of 3:1) of the microsphere grading and collection system. Two groups of screens 412 are arranged in the collection bin 410, with apertures of 50 μm and 10 μm from top to bottom, respectively. The top 50 μm screen 412 captures unqualified L-polylactic acid microspheres for recycling and reprocessing, and microspheres with undersized sizes are discharged and collected from the 10 μm screen 412; the L-polylactic acid microspheres intercepted by the 10 μm screen 412 are transported to the cyclone separation mechanism 420 by the negative pressure suction mechanism 413, and the centrifugal cyclone in the cyclone separation mechanism 420 performs secondary classification, and the small particle microspheres that meet the size requirements are separated into the collector at the bottom by the high-speed rotating airflow, thereby obtaining L-polylactic acid microspheres that can be used in the medical beauty field.

[0066] The appearance of the microspheres was tested, and the performance results of the microspheres after being processed by the cyclone separation mechanism 420 are shown in Table 1 below.

[0067] Example 3

[0068] This embodiment uses the device of embodiment 1 to prepare polymer microspheres for use in the medical field, and the particle size range of the microspheres is 1 micron to 10 microns.

[0069] The steps of this embodiment are as follows:

[0070] S1. The preheating temperature of the feed-preheating synchronization unit 110 is set to 120°C, and the hot air guide mechanism 111 conveys the hot air flow to the solid-gas mixing cylinder 113. The thermocouple sensor 116 and the electric heating wire 115 control the air flow temperature entering the solid-gas mixing cylinder 113 to 120°C; irregularly shaped polylactic acid particles (molecular weight range of 120,000, viscosity range of 0.6 dL / g, purity of 99%, particle size of 30μm to 50μm) are introduced into the solid-gas mixing cylinder 113 through the powder feeding mechanism 112, and coupled with the 120°C hot air flow to form a solid-gas mixture; the high-speed jet powder spraying unit 120 stably transports the solid-gas mixture to the solid-gas sheath flow guide unit 130, and under the action of the auxiliary air flow of the air guide head 133 and the two sets of flow stabilizing screens 134, the polylactic acid particles form a sheath flow effect in the guide box 132, and are discharged from the middle into the spheroidization system in a centralized manner;

[0071] S2. The shower-type dispersion mechanism 211 disperses the preheated polylactic acid particles into fine particle groups and feeds them into the spheroidizing furnace 210 (7 meters in length, with a ratio of 10:1 between its inner diameter and the inner diameter of the outlet of the receiving hopper 230). The spheroidizing furnace 210 is divided into three different temperature zones (200°C, 180°C, and 160°C) from top to bottom. The temperature of the cooling hopper 230 zone is controlled at 80°C by a circulating cooling system (using 0°C to 10°C cold water as the cooling fluid). The polylactic acid particles melt in the spheroidizing furnace 210 and fall into the cooling hopper 230 for cooling, thereby forming polylactic acid microspheres.

[0072] S3. After being discharged from the cooling hopper 230, the polylactic acid microspheres enter the collection chamber 410 of the microsphere classification and collection system. Two sets of screens 412 are set in the collection chamber 410, with apertures of 10 μm and 1 μm from top to bottom. The top 10 μm screen 412 captures unqualified polylactic acid microspheres for recycling and reprocessing, and microspheres with too small sizes are discharged and collected from the 1 μm screen 412; the polylactic acid microspheres intercepted by the 1 μm screen 412 are transported to the cyclone separation mechanism 420 by the negative pressure suction mechanism 413. The centrifugal cyclone in the cyclone separation mechanism 420 performs secondary classification, and the small particle microspheres that meet the size requirements are separated into the collector at the bottom by the high-speed rotating airflow, thereby obtaining polylactic acid microspheres that can be used in the medical field.

[0073] The appearance of the microspheres was inspected, and the drug loading rate was tested using UV-visible spectrophotometry. Specifically, the anti-tumor drug doxorubicin was loaded onto the polylactic acid microspheres of this embodiment and then dissolved in a suitable solvent (such as dilute hydrochloric acid) to completely release the drug. The absorbance of the sample solution was measured using a UV-visible spectrophotometer, and the concentration and mass of the drug were calculated based on the standard curve. The drug loading rate (%) was calculated as 100*drug mass / polymer microsphere mass.

[0074] The performance results of the microspheres after being processed by the cyclone separation mechanism 420 are shown in Table 1 below.

[0075] Example 4

[0076] This embodiment uses the device of embodiment 1 to prepare polymer microspheres for use in the field of 3D printing, and the particle size range of the polymer microspheres is 20 microns to 80 microns.

[0077] The steps of this embodiment are as follows:

[0078] S1. The preheating temperature of the feed-preheating synchronization unit 110 is set to 80°C, and the hot air guide mechanism 111 conveys the hot air flow to the solid-gas mixing cylinder 113. The thermocouple sensor 116 and the electric heating wire 115 control the air flow temperature entering the solid-gas mixing cylinder 113 to 80°C; irregularly shaped polylactic acid particles (molecular weight range of 120,000, viscosity range of 0.6 dL / g, purity of 99%, particle size of 100μm to 150μm) are introduced into the solid-gas mixing cylinder 113 through the powder feeding mechanism 112, and coupled with the 80°C hot air flow to form a solid-gas mixture; the high-speed jet powder spraying unit 120 stably transports the solid-gas mixture to the solid-gas sheath flow guide unit 130, and under the action of the auxiliary air flow of the air guide head 133 and the two sets of flow stabilizing screens 134, the polylactic acid particles form a sheath flow effect in the guide box 132, and are discharged from the middle into the spheroidization system in a centralized manner;

[0079] S2. The shower-type dispersion mechanism 211 disperses the preheated polylactic acid particles into fine particle groups and feeds them into the spheroidizing furnace 210 (7 meters in length, with a ratio of 10:1 between its inner diameter and the inner diameter of the outlet of the receiving hopper 230). The spheroidizing furnace 210 is divided into three different temperature zones (180°C, 170°C, and 160°C) from top to bottom. The temperature of the cooling hopper 230 zone is controlled to 70°C by a circulating cooling system (using 0°C to 10°C cold water as the cooling fluid). The polylactic acid particles melt in the spheroidizing furnace 210 and fall into the cooling hopper 230 for cooling, thereby forming polylactic acid microspheres.

[0080] S3. After being discharged from the cooling hopper 230, the polylactic acid microspheres enter the collection chamber 410 of the microsphere classification and collection system. Two groups of screens 412 are set in the collection chamber 410, with apertures of 80 μm and 20 μm from top to bottom, respectively. The top 80 μm screen 412 captures unqualified polylactic acid microspheres for recycling and reprocessing, and microspheres with too small sizes are discharged and collected from the 20 μm screen 412; the polylactic acid microspheres intercepted by the 20 μm screen 412 are transported to the cyclone separation mechanism 420 by the negative pressure suction mechanism 413. The centrifugal cyclone in the cyclone separation mechanism 420 performs secondary classification, and the small particle microspheres that meet the size requirements are separated into the collector at the bottom by the high-speed rotating airflow, thereby obtaining polylactic acid microspheres that can be used in the medical field.

[0081] The appearance of the microspheres was tested, and the performance results of the microspheres after being processed by the cyclone separation mechanism 420 are shown in Table 1 below.

[0082] The polylactic acid microspheres prepared in this embodiment are used as raw materials for 3D printing to prepare a scaffold, which has a personalized appearance and an internal microporous structure, and has a high density.

[0083] Example 5

[0084] This embodiment uses the apparatus of embodiment 1 to prepare microspheres from a composite material of inorganic filler (silicon dioxide) and polymer powder (polylactic acid), the particle size of which ranges from 20 microns to 50 microns.

[0085] The steps of this embodiment are as follows:

[0086] S1. First, the inorganic filler (silicon dioxide) and the polymer powder (polylactic acid) are compounded by melt extrusion technology, and uniform dispersion is achieved through high-temperature melting and shearing. The polymer particles are then processed by low-temperature crushing method, and the material is embrittled by freezing with liquid nitrogen and then crushed to obtain a small and irregular composite powder (particle size of 80μm to 100μm);

[0087] S2. Set the preheating temperature of the feed-preheating synchronization unit 110 to 110°C, and the hot air guide mechanism 111 conveys the hot air flow to the solid-gas mixing cylinder 113. The thermocouple sensor 116 and the electric heating wire 115 control the temperature of the air flow entering the solid-gas mixing cylinder 113 to 110°C; the composite powder enters the solid-gas mixing cylinder 113 through the powder feeding mechanism 112, and is coupled with the 110°C hot air flow to form a solid-gas mixture; the high-speed jet powder spraying unit 120 stably transports the solid-gas mixture to the solid-gas sheath flow guide unit 130. Under the action of the auxiliary air flow of the air guide head 133 and the two sets of flow stabilizing screens 134, the composite particles form a sheath flow effect in the guide box 132, and are discharged from the middle into the spheroidization system in a centralized manner;

[0088] S3. The shower-type dispersion mechanism 211 disperses the preheated composite particles into fine particle groups and feeds them into the spheroidizing furnace 210 (7 meters in length, with a ratio of 10:1 between its inner diameter and the inner diameter of the outlet of the receiving hopper 230). The spheroidizing furnace 210 is divided into three different temperature zones (210°C, 190°C, and 180°C) from top to bottom. The temperature of the cooling hopper 230 zone is controlled at 90°C by a circulating cooling system (using cold water at 0°C to 10°C as the cooling fluid). The composite particles melt in the spheroidizing furnace 210 and fall into the cooling hopper 230 for cooling, thereby forming composite microspheres.

[0089] S4. After being discharged from the cooling hopper 230, the composite microspheres enter the collection bin 410 of the microsphere grading and collection system. Three groups of screens 412 are arranged in the collection bin 410, with apertures of 50 μm and 20 μm from top to bottom. The top 50 μm screen 412 intercepts and captures unqualified composite microspheres for recycling and reprocessing, and microspheres with too small sizes are discharged and collected from the 20 μm screen 412; the composite microspheres intercepted by the 20 μm screen 412 are transported to the cyclone separation mechanism 420 by the negative pressure suction mechanism 413, and the centrifugal cyclone in the cyclone separation mechanism 420 performs secondary classification, and separates small particle microspheres that meet the size requirements into the collector at the bottom through high-speed rotating airflow, thereby obtaining composite microspheres that can be used in the fields of medicine or medical aesthetics.

[0090] The appearance of the microspheres was tested, and the performance results of the microspheres after being processed by the cyclone separation mechanism 420 are shown in Table 1 below.

[0091] Comparative Example 1

[0092] On the basis of the device of Example 1, this comparative example deletes the preheating structure in the solid-gas mixing cylinder 113 of the feeding system. Specifically, the airflow input by the hot air drainage mechanism 111 is changed to normal temperature air, and the electric heating wire 115 is deleted from the solid-gas mixing cylinder 113. Other structures and components are consistent with those of Example 1.

[0093] The spheroidization processes of Examples 2 to 5 were respectively carried out using the apparatus of this comparative example, and the performance of the products is shown in Table 1.

[0094] Among them, Comparative Example 1-1 adopts the same process as Example 2, the only difference is S1, and the other steps are consistent with Example 2. S1 of Comparative Example 1-1 is specifically: irregularly shaped left-handed polylactic acid particles (molecular weight range is 120,000, viscosity range is 0.6dL / g, purity is 99%, and particle size is 40μm~80μm) are introduced into the solid-gas mixing barrel 113 through the powder feeding mechanism 112, and coupled with the air to form a solid-gas mixture; the high-speed jet powder spraying unit 120 stably transports the solid-gas mixture to the solid-gas sheath flow guide unit 130, and under the action of the auxiliary airflow of the air guide head 133 and the two sets of flow stabilizing screens 134, the left-handed polylactic acid particles form a sheath flow effect in the guide box 132, and are discharged from the middle into the spheroidization system in a centralized manner. The final product performance is shown in Table 1.

[0095] Among them, Comparative Example 1-2 adopts the same process as Example 3, the only difference is S1, and the other steps are consistent with Example 3. S1 of Comparative Example 1-2 is specifically as follows: irregularly shaped polylactic acid particles (molecular weight range is 120,000, viscosity range is 0.6dL / g, purity is 99%, particle size is 30μm~50μm) enter the solid-gas mixing barrel 113 through the powder feeding mechanism 112, and couple with air to form a solid-gas mixture; the high-speed jet powder spraying unit 120 stably transports the solid-gas mixture to the solid-gas sheath flow guide unit 130, and under the action of the auxiliary airflow of the air guide head 133 and the two sets of flow stabilizing screens 134, the polylactic acid particles form a sheath flow effect in the guide box 132, and are discharged from the middle into the spheroidization system in a centralized manner. The final product performance is shown in Table 1.

[0096] Among them, Comparative Examples 1-3 adopt the same process as Example 4, with the only difference being S1, and the other steps are consistent with Example 4. S1 of Comparative Example 1-1 is specifically as follows: irregularly shaped polylactic acid particles (molecular weight range of 120,000, viscosity range of 0.6 dL / g, purity of 99%, particle size of 100 μm to 150 μm) are introduced into the solid-gas mixing barrel 113 through the powder feeding mechanism 112, and coupled with the air to form a solid-gas mixture; the high-speed jet powder spraying unit 120 stably transports the solid-gas mixture to the solid-gas sheath flow guide unit 130, and under the action of the auxiliary airflow of the air guide head 133 and the two sets of flow stabilizing screens 134, the polylactic acid particles form a sheath flow effect in the guide box 132, and are discharged from the middle into the spheroidization system in a centralized manner. The final product properties are shown in Table 1.

[0097] Comparative Examples 1-4 employ the same process as Example 5, differing only in S2. All other steps are consistent with Example 5. Specifically, S2 in Comparative Examples 1-4 involves the following steps: The composite powder enters the solid-gas mixing drum 113 through the powder feed mechanism 112, where it is coupled with air to form a solid-gas mixture. The high-speed jet powder spraying unit 120 stably transports the solid-gas mixture to the solid-gas sheath flow guide unit 130. Under the influence of the auxiliary airflow from the air guide head 133 and two sets of flow-stabilizing screens 134, the composite particles form a sheath flow effect within the guide box 132, and are discharged centrally from the center into the spheroidization system. The final product properties are shown in Table 1.

[0098] Comparative Example 2

[0099] Based on the device of Example 1, the solid-gas sheath flow guide unit 130 in the feeding system is deleted in this comparative example, and the other structures and components are consistent with those of Example 1.

[0100] The spheroidization processes of Examples 2 to 5 were carried out using the apparatus of this comparative example. Comparative Examples 2-1 to 2-4 employed the same processes as Examples 2 to 5, differing only in that the solid-gas sheath flow guide unit 130 was omitted. The properties of the final products are shown in Table 1.

[0101] Comparative Example 3

[0102] On the basis of the device of Example 1, the shower-type dispersion mechanism 211 in the spheroidization system of this comparative example is replaced with a conventional feeding mechanism, such as a high-temperature resistant stainless steel nozzle. Other structures and components are consistent with those of Example 1.

[0103] The spheroidization processes of Examples 2 through 5 were carried out using the apparatus of this comparative example. Comparative Examples 3-1 and 3-4 employed the same processes as Examples 2 through 5, differing only in that the showerhead-style dispersion mechanism 211 was replaced with a high-temperature-resistant stainless steel nozzle. The properties of the final product are shown in Table 1.

[0104] Table 1

[0105] Detection object Sphericity Particle size range / μm Angle of repose / ° Drug loading rate% Example 2 0.92 15-30 29 / Example 3 0.93 1-10 29 55 Example 4 0.94 30-50 30 / Example 5 0.94 30-40 28 / Comparative Example 1-1 0.82 15-40 33 / Comparative Example 1-2 0.84 1-10 35 47 Comparative Examples 1-3 0.85 30-50 32 / Comparative Examples 1-4 0.82 30-40 34 / Comparative Example 2-1 0.78 15-40 36 / Comparative Example 2-2 0.78 1-10 37 39 Comparative Examples 2-3 0.82 30-50 35 / Comparative Examples 2-4 0.79 30-40 35 / Comparative Example 3-1 0.78 15-40 36 / Comparative Example 3-2 0.78 1-10 37 39 Comparative Example 3-3 0.8 30-50 36 / Comparative Examples 3-4 0.78 30-40 36 /

[0106] As can be seen from the data in Table 1, the organic microspheres or organic-inorganic composite microspheres prepared in Examples 2 to 5 have controllable particle sizes and more uniform distribution, sphericity ≥ 0.9, and angle of repose ≤ 30°. The physical and chemical properties of the powders do not change significantly before and after spheroidization. They can be used in the fields of medical aesthetics, medical treatment, and 3D printing, and the drug loading rate is ≥ 50% in biomedical applications.

[0107] By comparing Examples 2 to 5 in Table 1 with Comparative Examples 1-1 to 1-4, it can be seen that after the air flow input by the hot air deflection mechanism 111 is changed to room temperature air, the particle size range of the microspheres produced is more dispersed, the sphericity decreases, the angle of repose increases, and the drug loading rate decreases.

[0108] By comparing Examples 2 to 5 in Table 1 with Comparative Examples 2-1 to 2-4, it can be seen that after the solid-gas sheath flow guide unit 130 is deleted, the sphericity of the microspheres obtained is greatly reduced, the angle of repose is significantly increased, and the drug loading rate is reduced.

[0109] By comparing Examples 2 to 5 in Table 1 with Comparative Examples 3-1 to 3-4, it can be seen that after the shower-type dispersion mechanism 211 is replaced with a conventional feeding mechanism, the sphericity of the microspheres produced is greatly reduced, the angle of repose is significantly increased, and the drug loading rate is reduced.

[0110] The above-described embodiments merely illustrate several implementations of the present invention, and while their descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that a person skilled in the art would be able to make numerous variations and improvements without departing from the spirit of the present invention, all of which fall within the scope of protection of the present invention. Therefore, the scope of protection of the present invention shall be determined by the appended claims.

Claims

1. A purely physical spheroidization device for polymer powders, characterized in that: The pure physical spheroidization device includes a feeding system, a spheroidization system, a circulating cooling system and a microsphere classification and collection system; the feeding system, the spheroidization system and the microsphere classification and collection system are connected in sequence; The feeding system is used to preheat the polymer powder and feed it to the spheroidization system, which includes a feeding-preheating synchronization unit, a high-speed jet powder spraying unit and a solid-gas sheath flow guide unit connected in sequence; The spheroidization system uses high-temperature spheroidization shaping technology to melt irregular polymer powder in a flowing state and then cool it to obtain polymer microspheres. The spheroidization system includes an elongated spheroidization furnace and a cooling hopper connected to the end of the spheroidization furnace. A shower-type dispersion mechanism connected to the outlet of the solid-gas sheath flow guide unit is suspended at the top of the spheroidization furnace. The spheroidization furnace is equipped with heating elements set in descending temperature, and the spheroidization furnace is divided into at least three sections along the axial direction. The circulating cooling system uses cryogenic fluid as a medium to regulate and cool the temperature inside the spheroidizing system.

2. A purely physical spheroidization device for polymer powders according to claim 1, characterized in that: The microsphere classification and collection system is used to classify and collect polymer microspheres through multi-stage particle capture; The microsphere classification and collection system includes a collection bin connected to the outlet of the cooling hopper and a cyclone separation mechanism connected to the discharge end of the collection bin; The collection chamber is internally provided with at least two layers of screens with different apertures for preliminary classification and collection of the polymer microspheres.

3. The purely physical spheroidization device for polymer powders according to claim 1, characterized in that: The spheroidizing furnace is provided with an adaptive temperature control unit, which includes a thermocouple array for real-time monitoring and feedback of the temperature of each section; A temperature sensor is provided in the cooling bucket.

4. The purely physical spheroidization device for polymer powders according to claim 1, characterized in that: The feeding-preheating synchronization unit includes a horizontal solid-gas mixing drum, a vertical powder feeding mechanism connected to the solid-gas mixing drum, a hot air drainage mechanism for conveying hot air to the solid-gas mixing drum, and a feeding pipe for conveying the solid-gas mixture to the high-speed jet powder spraying unit; A thermocouple sensor is provided at the junction of the solid-gas mixing cylinder and the hot air drainage mechanism for monitoring the temperature of the hot air flow; and an electric heating wire is installed on the solid-gas mixing cylinder.

5. A purely physical spheroidization device for polymer powders according to claim 4, characterized in that: The high-speed jet powder spraying unit includes a jet power device connected to the end of the feed pipe, a porous nozzle and a feed pipe connected to the outlet of the jet power device, and the end of the feed pipe extends to the inlet of the solid-gas sheath flow guide unit.

6. The purely physical spheroidization device for polymer powders according to claim 5, characterized in that: The solid-gas sheath flow guide unit is connected to the inlet end of the spheroidization system, and the solid-gas sheath flow guide unit includes a guide box with an upper cylinder and a lower cone structure, and a feed nozzle connected to the end of the feed pipe is suspended in the middle of the top of the guide box; At least two groups of evenly distributed air guide heads are arranged around the periphery of the feed nozzle, and the air guide heads are connected to an external blower to concentrate the polymer powder sprayed from the feed nozzle to the middle; At least two groups of flow stabilizing mesh plates are arranged in the flow guide box, and the apertures of the flow stabilizing mesh plates of each group decrease in sequence from top to bottom.

7. The purely physical spheroidization device for polymer powders according to claim 1, characterized in that: The ratio of the inner diameter of the spheroidizing furnace to the inner diameter of the cooling hopper outlet is 5 to 15:1; and the length of the spheroidizing furnace is not less than 3 meters; The shower-type dispersion mechanism includes a high-temperature resistant stainless steel nozzle and a microporous dispersion disk.

8. The purely physical spheroidization device for polymer powders according to claim 1, characterized in that: The spheroidizing furnace is also provided with a visual real-time monitoring device, which is embeddedly installed on the outer wall of the end of the spheroidizing furnace; the visual real-time monitoring device includes a high-temperature resistant optical window and a high-speed camera system.

9. The purely physical spheroidization device for polymer powders according to claim 1, characterized in that: The circulating cooling system includes cooling pipes surrounding the outer walls of the spheroidizing furnace and the cooling hopper, a cooling tank for storing cooling fluid, a liquid inlet mechanism for transporting the cooling fluid to different areas of the cooling pipes, and a drain pipe for discharging the cooling fluid after absorbing heat.

10. The purely physical spheroidization device for polymer powders according to claim 2, characterized in that: The length-to-diameter ratio of the collection bin is designed to be 2 to 4:1; The collection bin includes a bin cylinder with at least two layers of screens with different apertures, and a negative pressure suction mechanism that transports the graded and collected polymer microspheres to the cyclone separation mechanism; the screens at each layer are designed to have apertures that decrease along the airflow direction.

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