A continuous supercritical fluid spinning system

Abstract

The application relates to a continuous supercritical fluid spinning system for continuously preparing micro-nano fiber non-woven fabric, which comprises a supercritical fluid spinning liquid preparation device, a micro-nano fiber supercritical spinning device, a secondary drawing and bundle collecting device of micro-nano fiber, the supercritical fluid spinning liquid preparation device is connected with the micro-nano fiber supercritical spinning device, the micro-nano fiber supercritical spinning device is arranged above the secondary drawing and bundle collecting device of micro-nano fiber, the supercritical fluid spinning liquid preparation device is used for continuously preparing uniform and stable supercritical fluid spinning liquid, the micro-nano fiber supercritical spinning device is used for preparing uniform and continuous micro-nano fiber, and the secondary drawing and bundle collecting device of micro-nano fiber is used for secondary drawing and bundle collecting of micro-nano fiber. Compared with the prior art, the continuous supercritical fluid spinning system can continuously prepare non-woven fabric with high strength, good barrier property and excellent air permeability.

Description

Technical Field

[0001] This invention relates to the field of spinning technology, and in particular to a continuous supercritical fluid spinning system. Background Technology

[0002] Flash spinning, also known as instantaneous solvent evaporation web formation, is a dry spinning technology. The fiber-forming polymer is dissolved in a suitable solvent under high temperature (a temperature far exceeding the solvent's boiling point at normal pressure) and high pressure to form a spinning solution. This solution is then injected into a spinning assembly under pressure and ejected from the spinneret. Due to the sudden pressure drop after ejection, the solvent absorbs a large amount of heat, rapidly evaporates, and generates a high-speed airflow, causing the polymer to cool and crystallize quickly, achieving high orientation and producing ultrafine fibers. The resulting nanofibers and microfibers can then be web-laid and fixed to form nonwoven fabrics. Nonwoven fabrics produced using this technology have excellent properties and wide applications, especially in medical and health protection and medical packaging. Flash-spun polyethylene nonwoven fabrics possess many excellent properties, such as excellent waterproof and breathable properties; the sheets have excellent strength, tear resistance, puncture resistance, and burst resistance; the sheets generally do not fuzz or generate dust; and they exhibit excellent performance over a wide temperature range.

[0003] However, the preparation of nonwoven fabrics using the flash evaporation method in China still faces significant challenges. Firstly, the preparation of supercritical fluid spinning solutions requires strict selection of raw materials and precise control of factors such as temperature, pressure, and the order of polymer and solvent addition during the reaction process. These factors directly affect the success of supercritical fluid spinning solution preparation and its resulting properties, ultimately influencing the properties of the final fibers. CN212492936U discloses a sealing device for a reaction vessel, including a drive motor, feed pipe, stirring shaft, stirring blades, pressure relief pipe, and pressure gauge. This device offers good sealing performance, with a secure sealing structure that prevents loosening, ensuring proper stirring of general solvent materials. However, it cannot precisely control the quality of solvent addition and lacks a dedicated re-designed channel, preventing secondary additions during the process and making it unsuitable for preparing spinning solutions with multiple components. CN210621006U discloses a melting reactor reaction device, including an external jacket, an internal stirring device, a compressed air inlet, and two metering tanks, which can achieve staggered and precise addition of materials and solvents; however, the device cannot achieve continuous supply of spinning solution, and its production efficiency needs to be further improved.

[0004] Secondly, flash evaporation devices suffer from problems such as precise temperature and pressure control in the high-pressure and low-pressure chambers, and solvent recovery and reuse. The development of flash evaporation devices is a prerequisite for producing high-performance nonwoven fabrics, and researchers have conducted a series of studies on this topic. CN110129907 discloses a flash spinning device for polyphenylene sulfide, including a housing, a spinneret, a high-pressure reactor, and a conveying mechanism. The housing has a spinning solution inlet, the spinneret is located inside the housing, the bottom of the high-pressure reactor is connected to the spinneret through the spinning solution inlet, and the conveying mechanism is located at the bottom of the housing. The device also includes a regulating valve and an interceptor, which are sequentially positioned above the spinneret. This invention successfully produced polyphenylene sulfide nonwoven fabrics, but the device suffers from inaccurate pressure control and lacks solvent recovery, resulting in resource waste. Furthermore, the solvent entering the atmosphere will pollute the air and affect human health. Therefore, there is an urgent need to develop a supercritical spinning device that can precisely control temperature and pressure, classify and recover solvents, and produce uniform and continuous micro and nanofibers.

[0005] Finally, the properties of nonwoven fabrics prepared from micro / nanofibers by roll forming (tear resistance, air permeability, filtration efficiency, etc.) still lag significantly behind those from the United States and Japan. The electrostatic fiber opening process in the flash evaporation method poses electrostatic safety hazards. Researchers have developed a method using high-pressure air to open the fibers, but this method currently suffers from problems such as fiber adhesion, difficulty in further refining the fibers, uneven fiber opening, poor fiber stability, and slow fiber web formation.

[0006] In summary, there is an urgent need to develop a continuous supercritical fluid spinning equipment to solve the problems mentioned above in the preparation of supercritical fluid spinning solution, spinning, fiber opening and collection processes, so as to achieve continuous production of nonwoven fabrics with high strength, good barrier properties and excellent air permeability. Summary of the Invention

[0007] The purpose of this invention is to overcome the defects of the prior art by providing a continuous supercritical fluid spinning system to achieve continuous production of nonwoven fabrics with high strength, good barrier properties, and excellent air permeability.

[0008] The objective of this invention can be achieved through the following technical solutions:

[0009] The purpose of this invention is to provide a continuous supercritical fluid spinning system for the continuous preparation of micro / nanofiber nonwoven fabrics. The continuous supercritical fluid spinning system includes a supercritical fluid spinning solution preparation device, a micro / nanofiber supercritical spinning device, and a secondary drafting and bundling collection device for micro / nanofibers. The supercritical fluid spinning solution preparation device is connected to the micro / nanofiber supercritical spinning device. The micro / nanofiber supercritical spinning device is positioned above the micro / nanofiber secondary drafting and bundling collection device. The supercritical fluid spinning solution preparation device is used to continuously prepare a uniform and stable supercritical fluid spinning solution. The micro / nanofiber supercritical spinning device is used to prepare uniform and continuous micro / nanofibers. The micro / nanofiber secondary drafting and bundling collection device is used for secondary drafting and bundling collection of micro / nanofibers.

[0010] Furthermore, the supercritical fluid spinning solution preparation device includes two reactors connected by multiple pipes; each reactor is equipped with an outer cooling and heating mechanism, an internal temperature and pressure sensor, a polymer feed port, and a pressure relief valve; the supercritical fluid spinning solution preparation device also includes a ring-shaped rotary shaft penetrating inside the reactor, the ring-shaped rotary shaft containing two asymmetrical double helical blades; the two reactors share a metering pump, which is located on the first pipe connecting the two reactors, and this pipe is also equipped with valves a and b; the second pipe connecting the two reactors is connected to a pressurizing mechanism and a vacuuming mechanism, and this pipe is also equipped with valves c and d, valve e and valve f.

[0011] Furthermore, the supercritical fluid spinning solution preparation device and the micro / nano fiber supercritical spinning device are connected by a third pipe that connects the two reactors. This pipe is also equipped with valve g and valve h.

[0012] Furthermore, the supercritical spinning device for micro and nanofibers includes a spinning chamber, a high-pressure chamber and a low-pressure chamber disposed within the spinning chamber, a solvent outlet disposed on the side of the spinning chamber, and a solvent recovery mechanism connected to the solvent outlet.

[0013] Furthermore, the secondary stretching and bundling device for the micro / nanofibers includes a spinning plate disposed in the spinning chamber, a fiber opening mechanism disposed below the spinning plate, a conveying mechanism disposed below the fiber opening mechanism, a negative pressure plate located in the conveying mechanism, a heating box, a hot pressure roller, a guide roller, and a winding device disposed on one side of the conveying mechanism.

[0014] Furthermore, both reactors are set to a volume of 2000ml, and both can be used to prepare solutions under high temperature and high pressure, especially suitable for the preparation of supercritical fluid spinning solutions.

[0015] Furthermore, when one of the reactors is working, valves b, d, and h are closed. Once the spinning solution is prepared in the reactor, valves a and c are closed, and valves b and d are opened as needed to achieve continuous preparation and supply of the spinning solution.

[0016] Furthermore, the material is fed from the polymer feed port, which is equipped with a sealing cap to prevent gas leakage and ensure constant pressure inside the reactor.

[0017] Furthermore, the annular rotary blade three-dimensional rotating shaft includes two asymmetrical spirals of different sizes, which can flip the material in the reactor from bottom to top back and forth, and its rotation speed can be set in the range of 0-1500 rpm / min.

[0018] Furthermore, the annular rotary blade three-dimensional rotating shaft includes two asymmetrical spirals of different sizes, which can flip the material in the reactor from bottom to top back and forth, and its rotation speed can be set in the range of 0-1500 rpm / min.

[0019] Furthermore, the cooling and heating mechanisms are activated, the maximum temperature tolerance of the reactor is 300℃, the recommended temperature control range is 180-220℃, and the heating method can be oil bath heating or electric heating.

[0020] Furthermore, when using a vacuum pumping mechanism to create a vacuum, valves c and f are open, while valve d is closed, in order to remove air and moisture from the reactor. The device can be either a vacuum pump or a compressor.

[0021] Furthermore, the temperature and pressure sensors are designed for real-time monitoring of the conditions inside the reactor, and their external control panel can display the temperature and pressure inside the reactor in real time.

[0022] Furthermore, when the solvent is metered into one of the reaction vessels by a metering pump, valve a is open and valve b is closed. Regardless of the state in which the solvent exists, the device can achieve precise metering of the solvent.

[0023] Furthermore, a pressurization mechanism is used in the operation of the reactor. Valves e and c are open, while valves d and f are closed. The maximum withstand pressure is 30 MPa, and the recommended actual operating pressure is 6-15 MPa. The pressurization mechanism uses a gas cylinder for pressurization, and the gas supplied can be one of nitrogen, argon, or helium.

[0024] Furthermore, the pressure relief valve is designed to prevent excessive pressure inside the reactor. It can control and regulate the pressure inside the reactor in real time and has a protective and warning function.

[0025] Furthermore, the high-pressure chamber is equipped with a sensor a, a fluid inlet a, and a safety valve a at the top, a fluid outlet a at the bottom, and a heating and insulation mechanism a outside the high-pressure chamber. The sensor a is used to monitor the temperature and pressure inside the high-pressure chamber, and the safety valve a is used to protect the high-pressure chamber. When the pressure exceeds the pressure set by the safety valve a, it can automatically open to reduce pressure and prevent excessive pressure from causing rupture or even explosion.

[0026] Furthermore, the high-pressure chamber can withstand a maximum pressure of 30 MPa and a maximum temperature of 500°C, and is equipped with explosion-proof components.

[0027] Furthermore, the maximum heating temperature of the heating and heat preservation mechanism a is 300℃, the general operating temperature is below 260℃, and the heating is paused after reaching the specified temperature, and the temperature in the high-pressure chamber remains unchanged for 10 to 40 minutes; the fluid inlet a is connected to a high-temperature and high-pressure resistant pipeline, and a flow regulating valve a is provided on the pipeline; the fluid outlet a is connected to a high-temperature and high-pressure resistant pipeline, and a flow regulating valve b is provided on the pipeline.

[0028] Furthermore, the low-pressure chamber and the high-pressure chamber have the same structure and configuration. The low-pressure chamber is equipped with a sensor b, a fluid inlet b, and a safety valve b at the top and a fluid outlet b at the bottom. The low-pressure chamber is equipped with a heating and insulation mechanism b outside. The high-pressure chamber and the low-pressure chamber are connected by a pipe. The low-pressure chamber is connected to the spinning plate by a pipe and a flow regulating valve c is provided on the pipe.

[0029] Furthermore, the flow regulating valves a, b, and c are connected to the control panel, and the flow regulating valves and flow rate are controlled by operating the control panel; the sensors a and b are connected to the display screen, which displays the temperature and pressure in real time.

[0030] Furthermore, the volume of the high-pressure chamber is 50-200 ml, and the volume of the high-pressure chamber is larger than the volume of the low-pressure chamber, with a difference of 10-40 ml between the volumes of the high-pressure chamber and the low-pressure chamber.

[0031] Furthermore, the spinning plate is provided with spinnerets; the spinnerets are cylindrical or conical in shape, and the number of spinnerets is 5 to 20.

[0032] Furthermore, the solvent recovery mechanism includes a condenser, a suction assembly, and a refrigeration assembly.

[0033] Furthermore, the solvent recovery mechanism includes a condenser a, a condenser b, a suction assembly a, a refrigeration assembly a, and a refrigeration assembly b; based on the different boiling points of the solvents, the solvents can be liquefied separately for recovery and reuse.

[0034] Furthermore, the solvent outlet is connected to the lower port of condenser a via a pipe, the upper port of condenser a is connected to the lower port of condenser b via a pipe, and the upper port of condenser b is connected to the suction assembly a via a pipe; the refrigeration assembly a is connected to condenser b via a pipe, and the refrigeration assembly b is connected to condenser a via a pipe; the solvent recovery mechanism designed in this way can recover different solvents separately, which helps to reuse the solvents.

[0035] Furthermore, the number of condensers and refrigeration components is not limited to two. When more than two types of solvents are used, the number of condensers and refrigeration components can be increased, and the connection method is the same.

[0036] Furthermore, the suction component a refers to generating negative pressure at the solvent outlet to improve solvent recovery efficiency; the temperature range of the cooling component a and the cooling component b is -40 to 50°C.

[0037] Furthermore, the fiber opening mechanism includes a heating component, a trumpet-shaped baffle a, an air outlet component, a trumpet-shaped baffle b, and a cylindrical baffle arranged sequentially from top to bottom. The purpose is to uniformly disperse the fiber bundle under the action of high-pressure airflow and further stretch the fiber.

[0038] Furthermore, the heating component is cylindrical in shape, and its heating temperature range is 50–200°C. The purpose of this heating component is to remove any incompletely evaporated solvent and prevent the fibers from sticking together. The heating method selected for the heating component is one of infrared heating, electromagnetic heating, or resistance heating.

[0039] Furthermore, the air outlet component is cylindrical in shape, with a gap inside. A compressed air outlet is installed at the gap opening of the air outlet component, and a compressed air inlet is connected to an air compression component through a pipe. A regulating valve is installed on the pipe to regulate the gas flow rate.

[0040] Furthermore, the internal gap of the air outlet assembly is annular in shape, with a gap diameter of 1–4 mm; the lower end diameter of the compressed air outlet is 2–8 mm.

[0041] Furthermore, the diameter of the spinning plate is 1:(3-8) of the inner diameter of the heating component, and the ratio of the upper inner diameter to the lower inner diameter of the trumpet-shaped baffle a is (2-5):1.

[0042] Furthermore, the conveying mechanism includes a collection net motor and a control component. The material of the collection net is selected from silicone, polyvinyl chloride, polyurethane, thermoplastic polyurethane elastomer rubber, etc. The collection net has uniformly distributed holes with a hole size of 0.5 to 3 mm and a hole shape selected from one or more combinations of circles, triangles, squares, and rhombuses.

[0043] Furthermore, the negative pressure plate is rectangular in shape with a height of 1 to 2.5 cm. Circular holes with a diameter of 2 to 5 mm are evenly distributed at the upper end of the negative pressure plate. An air intake is opened at the lower end of the negative pressure plate and is connected to the suction assembly b through a pipe.

[0044] Furthermore, the width of the collecting net is (1~1.2):1 with the diameter of the cylindrical baffle, and the distance between the lower end of the cylindrical baffle and the collecting net is 20~80cm.

[0045] Furthermore, the winding device is equipped with a collecting roller.

[0046] Furthermore, the heating length range of the heating box is 1 to 6 m, and the maximum heating temperature of the heating box is 300°C; the maximum heating temperature of the hot pressing roller is 150°C, the speed is 5 to 15 m / min, and the distance between the hot pressing rollers is 0.05 to 1.5 mm.

[0047] Furthermore, the distance between the right end of the heating box and the hot pressing roller is 10-50cm, the distance between the hot pressing roller and the guide roller is 30-80cm, and the distance between the guide roller and the collecting roller is 10-40cm.

[0048] The specific mechanism of this invention is as follows:

[0049] First, the polymer raw material is added to the reactor through the polymer feed port. The feed port is then closed, and the vacuum mechanism is activated. The corresponding valves are opened to remove air and moisture, especially oxygen, from the reactor to prevent further physicochemical reactions under high pressure. A ring-shaped rotary impeller is opened for slow stirring, and preheating is achieved through a cooling and heating system, providing a foundation for the subsequent addition of solvent to dissolve the polymer. A metering pump precisely adds the solvent to the reactor to ensure accurate preparation of the spinning solution. Simultaneously, the gas tank valve is opened to pressurize the reactor to the required pressure, bringing the polymer-solvent mixture to a supercritical state. The ring-shaped rotary impeller is then accelerated, utilizing its two-bladed double helix of varying sizes and its asymmetrical stirring action to increase the range of motion and contact surface area of ​​the mixture, ensuring thorough contact between the solvent and polymer and resulting in a homogeneous mixture. During this process, temperature and pressure sensors are monitored, and corresponding switches are adjusted to maintain constant temperature and pressure, ensuring fluid stability and preparing a uniform and stable supercritical fluid spinning solution. Finally, the corresponding valves are opened, and the high pressure within the reactor forces the supercritical fluid spinning solution out of the discharge port.

[0050] Then, the supercritical fluid spinning solution enters the high-pressure chamber. Sensors monitor the temperature and pressure of the high-pressure chamber, which can be observed on a display screen. The safety valve is set to the same specified pressure value as the high-pressure chamber. When the pressure in the high-pressure chamber exceeds the pressure set by the safety valve, the safety valve automatically releases pressure, ensuring a constant pressure in the high-pressure chamber and preventing the danger of rupture due to excessive pressure. When the pressure in the high-pressure chamber is the same as that in the reactor, the flow regulating valve at the top of the low-pressure chamber is opened, allowing the supercritical fluid spinning solution to enter the low-pressure chamber, resulting in slight phase separation. The safety valve and sensors in the low-pressure chamber function the same as those in the high-pressure chamber. Once the pressure in the low-pressure chamber reaches the target pressure, the flow regulating valve at the lower end of the low-pressure chamber is opened, and the spinning solution is sprayed out from the spinning plate. The solvent evaporates suddenly, and the polymer cools and solidifies rapidly to form fiber bundles. The fiber bundles pass through the heating assembly to further remove residual solvent from the fiber bundles and prevent the fibers in the fiber bundles from sticking together. Subsequently, the fiber bundles pass through the high-pressure airflow area, where the fibers are evenly separated under the action of the high-pressure airflow. Due to the speed difference between the fibers, the fibers undergo secondary stretching, further refining the fibers. After passing through the high-pressure airflow zone, the negative pressure causes the high-speed fibers to be adsorbed, preventing them from scattering and ensuring they are evenly deposited on the collecting net to form a fluffy fiber network. This network is then conveyed to the spinning room and introduced into a heating chamber to soften the fibers. Hot rollers then press the softened network to form a nonwoven fabric, creating bonding points between the fibers and improving its mechanical strength. The nonwoven fabric then passes through guide rollers and is finally collected by a winding device equipped with multiple collection rollers for continuous collection, improving production efficiency. A suction assembly guides the solvent gas from the solvent outlet into the condenser. Depending on the solvent's boiling point, a refrigeration assembly provides different cooling temperatures to the condenser, allowing the solvent to be liquefied sequentially in different condensers. This enables the classified recovery and reuse of the solvent.

[0051] Compared with the prior art, the present invention has the following beneficial effects:

[0052] 1) The continuous supercritical fluid spinning system provided by the present invention saves equipment space by setting up two reaction vessels, sharing a set of pressure device and solvent addition device, and together with the subsequent spinning process, the efficiency of supercritical fluid spinning solution preparation can be improved by valve switching control, thus realizing continuous production.

[0053] 2) The continuous supercritical fluid spinning system provided by the present invention uses a three-dimensional rotating shaft with ring blades, which greatly increases the activity space of the polymer and solvent. During the tumbling process, it obtains more surface area, increases the contact probability, and helps to fully mix the solvent and polymer under high pressure, so that the prepared supercritical fluid spinning solution is more uniform and more stable in properties.

[0054] 3) The continuous supercritical fluid spinning system provided by this invention introduces a metering pump, which can accurately measure the solvent when adding solvent, regardless of the form of the solvent under pressure, and prepare a supercritical fluid spinning solution with more stable properties.

[0055] 4) The continuous supercritical fluid spinning system provided by the present invention uses a flow regulating valve to precisely control the pressure in the high-pressure chamber, low-pressure chamber and at the spinning plate, thereby avoiding unstable liquid supply caused by pressure fluctuations. With the use of a safety valve, it avoids danger caused by excessive pressure, thus achieving a safe and stable supply of spinning solution.

[0056] 5) The continuous supercritical fluid spinning system provided by the present invention utilizes a refrigeration component to provide different cooling temperatures to the condenser, and utilizes the different boiling points of the solvents to liquefy the solvents separately. This not only recovers the solvents but also separates the different solvents, which helps to reuse the solvents and saves resources.

[0057] 6) The continuous supercritical fluid spinning system provided by the present invention, by setting the heating component below the spinning plate, allows the fiber bundle to pass through the heating component, which is beneficial for further removal of solvent; and the design of the air fiber opening and stretching device allows the fiber bundle to be opened and stretched evenly, thereby improving the fiber distribution uniformity and diameter fineness.

[0058] 7) The continuous supercritical fluid spinning system provided by this invention, with its negative pressure device design, avoids the high-speed moving fibers from scattering everywhere, and the fibers can be more evenly adsorbed on the collection net, which can significantly improve the performance of nonwoven fabrics.

[0059] 8) The continuous supercritical fluid spinning system provided by the present invention uses a heating box to heat the nonwoven fabric and uses hot press rollers to roll it, so that bonding points are formed between the fibers of the nonwoven fabric, thereby improving the mechanical strength of the nonwoven fabric; and uses a multi-roller winding device to collect the nonwoven fabric, which can realize the continuous collection of nonwoven fabric and improve production efficiency. Attached Figure Description

[0060] Figure 1 This is a schematic diagram of the continuous supercritical fluid spinning system in this invention.

[0061] Figure 2 This is a schematic diagram of the supercritical fluid spinning solution preparation device in this invention.

[0062] Figure 3 This is a schematic diagram of the supercritical spinning device for micro and nanofibers in this invention.

[0063] Figure 4 This is a top view of the spinning plate of the supercritical spinning device for micro / nano fibers in this invention.

[0064] Figure 5 This is a schematic diagram of the spinneret orifice of the supercritical spinning device for micro / nano fibers in this invention.

[0065] Figure 6 This is a schematic diagram of the secondary stretching and bundling collection device for micro / nano fibers in this invention.

[0066] Figure 7 This is a top view of the negative pressure plate of the secondary stretching and bundling collection device for micro and nanofibers in this invention.

[0067] The numbers in the diagram are as follows:

[0068] 1-Reaction vessel, 2-Double spiral stirring rod, 3-Metering pump, 4-Refrigeration and heating mechanism, 5-Temperature and pressure sensor, 6-Pressure mechanism, 7-Polymer feed port, 8-Pressure relief valve, 9-Vacuuming mechanism, 10-Valve a, 11-Valve b, 12-Valve c, 13-Valve d, 14-Valve e, 15-Valve f, 16-Valve g, 17-Valve h, 18-Control panel, 19-Display screen, 20-Spinning chamber, 21-Flow regulating valve a, 22-Sensor a, 23-Fluid inlet a, 24-Fluid outlet a, 25-Flow regulating valve b, 26-Sensor b, 27-Fluid inlet b, 28-Fluid outlet b, 29-Safety valve a, 30-High pressure chamber, 31-Heating and insulation mechanism a, 32-Safety valve b, 33 -Low-pressure chamber, 34-Heating and insulation mechanism b, 35-Flow regulating valve c, 36-Spinning plate, 37-Solvent outlet, 38-Condenser a, 39-Condenser b, 40-Suction assembly a, 41-Refrigeration assembly a, 42-Refrigeration assembly b, 43-Regulating valve, 44-Air compression assembly, 45-Heating assembly, 46-Compressed air inlet, 47-Compressed air outlet, 48-Collection net, 49-Suction assembly b, 50-Fiber bundle, 51-Flare baffle a, 52-Air outlet assembly, 53-Flare baffle b, 54-Cylindrical baffle, 55-Loose fiber network, 56-Inlet, 57-Negative pressure plate, 58-Heating box, 59-Hot press roller, 60-Guide roller, 61-Winding equipment, 62-Collection roller, 361-Spinneret. Detailed Implementation

[0069] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. Component models, material names, connection structures, control methods, and other features not explicitly described in this technical solution are considered common technical features disclosed in the prior art.

[0070] A continuous supercritical fluid spinning system is disclosed for the continuous preparation of micro / nanofiber nonwoven fabrics. The system includes a supercritical fluid spinning solution preparation device, a micro / nanofiber supercritical spinning device, and a secondary drafting and bundling collection device for the micro / nanofibers. The supercritical fluid spinning solution preparation device is connected to the micro / nanofiber supercritical spinning device. The micro / nanofiber supercritical spinning device is positioned above the secondary drafting and bundling collection device. The supercritical fluid spinning solution preparation device is used to continuously prepare a uniform and stable supercritical fluid spinning solution. The micro / nanofiber supercritical spinning device is used to prepare uniform and continuous micro / nanofibers. The secondary drafting and bundling collection device is used for bundling and collecting the micro / nanofibers during the secondary drafting process.

[0071] In some specific embodiments, the supercritical fluid spinning solution preparation device includes two reactors 1 connected by multiple pipes; each reactor 1 is equipped with an outer cooling and heating mechanism 4, an internal temperature and pressure sensor 5, a polymer feed port 7, and a pressure relief valve 8; the supercritical fluid spinning solution preparation device also includes a ring-shaped rotary shaft 2 penetrating inside the reactor 1, the ring-shaped rotary shaft 2 comprising two asymmetrical double helical blades; the two reactors 1 share a metering pump 3, which is located on the first pipe connecting the two reactors 1, and this pipe is also equipped with valves a10 and b11; the second pipe connecting the two reactors is connected to a pressurizing mechanism 6 and a vacuuming mechanism 9, and this pipe is also equipped with valves c12, d13, e14, and f15.

[0072] In some specific embodiments, the supercritical spinning device for micro and nanofibers includes a spinning chamber 20; a high-pressure chamber 30 and a low-pressure chamber 33 disposed within the spinning chamber 20; a solvent outlet 37 disposed on the side of the spinning chamber 20; and a solvent recovery mechanism connected to the solvent outlet 37.

[0073] In some specific embodiments, the secondary stretching and bundling collection device for micro and nanofibers includes a spinning plate 36 disposed in the spinning chamber 20; a fiber opening mechanism disposed below the spinning plate 36; a conveying mechanism disposed below the fiber opening mechanism; a negative pressure plate 57 located in the conveying mechanism; and a heating box 58, a hot pressure roller 59, a guide roller 60, and a winding device 61 disposed on one side of the conveying mechanism.

[0074] Example

[0075] See Figures 1 to 7This embodiment provides a continuous supercritical fluid spinning system, including:

[0076] The supercritical fluid spinning solution preparation device consists of two reactors 1 connected by multiple pipes, equipped with an outer cooling and heating mechanism 4, an internal temperature and pressure sensor 5, a polymer feed port 7, and a pressure relief valve 8. The supercritical fluid spinning solution preparation device also includes a three-dimensional rotating shaft 2 with a ring blade through the interior of the two reactors 1, containing two unequal-sized double helical blades. The two reactors 1 share a metering pump 3, which also includes valves a10 and b11. A pressurizing mechanism 6 and a vacuuming mechanism 9 are connected to the outside of the two reactors 1.

[0077] Supercritical spinning device for micro and nanofibers: spinning chamber 20, high pressure chamber 30 and low pressure chamber 33 disposed in spinning chamber 20, solvent outlet 37 disposed on the side of spinning chamber 20, and solvent recovery mechanism connected to solvent outlet 37.

[0078] The secondary stretching and bundling collection device for micro and nanofibers includes: a spinning chamber 20, a spinning plate 36 disposed in the spinning chamber 20, a fiber opening mechanism disposed below the spinning plate 36, a conveying mechanism disposed below the fiber opening mechanism, a negative pressure plate 57 disposed in the conveying mechanism, a heating box 58 disposed on one side of the conveying mechanism, a hot pressure roller 59, a guide roller 60, and a winding device 61.

[0079] The supercritical fluid spinning solution preparation device and the micro / nano fiber supercritical spinning device are connected by a third pipe that connects the two reactors. This pipe is also equipped with valves g16 and h17.

[0080] Please see Figure 2 As shown, the volume of both reactors 1 is set to 2000ml, and both can be used to prepare solutions under high temperature and high pressure, especially suitable for the preparation of supercritical fluid spinning solutions.

[0081] Please see Figure 2 As shown, when one of the reactors 1 (denoted as reactor a and the other reactor b) is working, valves b11, d13, and h17 are closed. After reactor 1 has finished preparing the spinning solution, valves a10 and c12 are closed. Valve b11 and d13 are opened as needed to achieve continuous preparation and supply of the spinning solution.

[0082] Please see Figure 2 As shown, the material is fed from the polymer feed port 7, which is equipped with a sealing cap to prevent gas leakage and ensure constant pressure inside the reactor 1.

[0083] Please see Figure 2As shown, the ring-shaped rotary shaft 2 includes two asymmetrical spirals of different sizes, which can flip the material in the reactor 1 back and forth from bottom to top. Its rotation speed can be set in the range of 0-1500 rpm / min.

[0084] Please see Figure 2 As shown, the cooling and heating mechanism 4 is open, the maximum temperature tolerance of the reactor 1 is 300℃, the temperature control range is 180-220℃, and the heating method can be oil bath heating or electric heating.

[0085] Please see Figure 2 As shown, when vacuuming is performed using vacuuming mechanism 9, valves C12 and F15 are open, and valve D13 is closed, in order to remove air and moisture from the reactor 1. Vacuuming mechanism 9 can be either a vacuum pump or a compressor.

[0086] Please see Figure 2 As shown, temperature and pressure sensor 5 is designed for real-time monitoring of the conditions inside the reactor. Its external control panel can display the temperature and pressure inside reactor 1 in real time.

[0087] Temperature and pressure sensors 5 are commonly used or purchased components, and those skilled in the art are capable of selecting the appropriate specifications, models, and parameters according to actual needs.

[0088] Please see Figure 2 As shown, when the solvent is metered into the reactor a by the metering pump 3, valve a10 is open and valve b11 is closed. Regardless of the state of the solvent, the metering pump 3 can accurately measure the solvent.

[0089] Please see Figure 2 As shown, the pressurizing mechanism 6 is used in the operation of the reactor a. Valves e14 and c12 are open, and valves d13 and f15 are closed. Its maximum withstand pressure is 30MPa, and the actual operating pressure is 6-15MPa. The pressurizing mechanism 6 uses a gas cylinder pressurization method, and the gas supplied can be one of nitrogen, argon, or helium.

[0090] Please see Figure 2 As shown, the pressure relief valve 8 is designed to prevent excessive pressure inside the reactor. It can control and adjust the pressure inside the reactor 1 in real time and has a protective and warning function.

[0091] Please see Figure 3As shown, the high-pressure chamber 30 is equipped with a sensor a22, a fluid inlet a23, and a safety valve a29 at its top, and a fluid outlet a24 at its bottom. A heating and insulation mechanism a31 is provided outside the high-pressure chamber 30. The sensor a22 is used to monitor the temperature and pressure inside the high-pressure chamber 30, and the safety valve a29 is used to protect the high-pressure chamber 30. When the pressure exceeds the pressure set by the safety valve a29, it can automatically open to reduce the pressure and prevent excessive pressure from causing rupture or even explosion.

[0092] Sensor A22 is a temperature and pressure sensor, which is a commonly used or purchased component. Those skilled in the art are capable of selecting the appropriate specifications, models, and parameters according to actual needs.

[0093] Please see Figure 3 As shown, the high-pressure chamber 30 can withstand a maximum pressure of 30 MPa and a maximum temperature of 500°C. The high-pressure chamber 30 is also equipped with explosion-proof components (not shown in the figure).

[0094] Please see Figure 3 As shown, the maximum heating temperature of the heating and heat preservation mechanism a31 is 300℃, the general operating temperature is below 260℃, and heating is paused after reaching the specified temperature, and the temperature in the high-pressure chamber 30 can be kept unchanged for 10 to 40 minutes; the fluid inlet a23 is connected to a high-temperature and high-pressure resistant pipe, and a flow regulating valve a21 is provided on the pipe; the fluid outlet a24 is connected to a high-temperature and high-pressure resistant pipe, and a flow regulating valve b25 is provided on the pipe.

[0095] Please see Figure 3 As shown, the low-pressure chamber 33 has the same structure and configuration as the high-pressure chamber 30. The low-pressure chamber 33 is equipped with a sensor b26, a fluid inlet b27 and a safety valve b32 at the top, and a fluid outlet b28 at the bottom. The low-pressure chamber 33 is equipped with a heating and insulation mechanism b34 on its exterior.

[0096] Sensor B26 is a temperature and pressure sensor, which is a commonly used or purchased component. Those skilled in the art are capable of selecting the appropriate specifications, models, and parameters according to actual needs.

[0097] Please see Figure 3 As shown, the high-pressure chamber 30 and the low-pressure chamber 33 are connected by a pipe. The low-pressure chamber 33 is connected to the spinning plate 36 by a pipe, and a flow regulating valve c35 is provided on the pipe.

[0098] Please see Figure 3As shown, the flow regulating valves a21, b25, and c35 are connected to the control panel 18, and the flow regulating valves and flow rate are controlled by operating the control panel 18; the sensors a22 and b26 are connected to the display screen 19, which displays the temperature and pressure in real time.

[0099] Please see Figure 3 As shown, the volume of the high-pressure chamber 30 is 50-200ml, and the volume of the high-pressure chamber 30 is larger than the volume of the low-pressure chamber 33. The volume difference between the high-pressure chamber 30 and the low-pressure chamber 33 is 10-40ml.

[0100] Please see Figure 4 and Figure 5 As shown, the spinning plate 36 has spinnerets 361 distributed on it. The spinnerets 361 are cylindrical and conical in shape, and the number of spinnerets 361 is 5 to 20.

[0101] Please see Figure 3 As shown, the solvent recovery mechanism includes a condenser a38, a condenser b39, a suction assembly a40, a refrigeration assembly a41, and a refrigeration assembly b42; based on the different boiling points of the solvents, the solvents can be liquefied separately for recovery and reuse.

[0102] Please see Figure 3 As shown, the solvent outlet 37 is connected to the lower port of condenser a38 via a pipe, the upper port of condenser a38 is connected to the lower port of condenser b39 via a pipe, and the upper port of condenser b39 is connected to the suction assembly a40 via a pipe; the refrigeration assembly a41 is connected to condenser b39 via a pipe, and the refrigeration assembly b42 is connected to condenser a38 via a pipe; the solvent recovery mechanism designed in this way can recover different solvents separately, which helps to reuse the solvent.

[0103] Please see Figure 3 As shown, the number of condensers and refrigeration components is not limited to two. When more than two types of solvents are used, the number of condensers and refrigeration components can be increased, and the connection method is the same.

[0104] Please see Figure 3 As shown, the suction component a40 refers to generating negative pressure at the solvent outlet 37 to improve solvent recovery efficiency; the temperature range of the cooling component a41 and the cooling component b42 is -40 to 50°C.

[0105] Please see Figure 6 As shown, the fiber opening mechanism includes a heating component 45, a horn-shaped baffle a51, an air outlet component 52, a horn-shaped baffle b53, and a cylindrical baffle 54. The purpose is to evenly disperse the fiber bundle 50 under the action of high-pressure airflow and further stretch the fiber.

[0106] Please see Figure 6 As shown, the heating component 45 is cylindrical in shape, and the heating temperature range of the heating component 45 is 50 to 200°C. The purpose is to remove the solvent that has not been completely evaporated and to avoid the adhesion between fiber bundles. The heating method of the heating component 45 is one of infrared heating, electromagnetic heating, and resistance heating.

[0107] Please see Figure 6 As shown, the air outlet component 52 is cylindrical in shape and has a gap inside. A compressed air outlet 47 is installed at the gap of the air outlet component 52. The compressed air inlet 46 is connected to the air compression component 44 through a pipe, and a regulating valve 43 is installed on the pipe to regulate the gas flow rate.

[0108] Please see Figure 6 As shown, the internal gap of the air outlet component 52 is annular in shape, with a gap diameter of 1 to 4 mm; the lower end diameter of the compressed air outlet 47 is 2 to 8 mm.

[0109] Please see Figure 6 As shown, the diameter of the spinning plate 36 and the inner diameter of the heating component 45 are 1:(3~8), and the ratio of the upper inner diameter to the lower inner diameter of the trumpet-shaped baffle a51 is (2~5):1.

[0110] Please see Figure 6 As shown, the conveying mechanism includes a collection net 48, a motor, and a control component (not shown in the figure). The material of the collection net 48 is selected from one of the following: silicone material, polyvinyl chloride material, polyurethane material, thermoplastic polyurethane elastomer rubber material, etc.

[0111] The control component includes a controller, which is a microcontroller or a processor based on x86, ARM, or RISC-V architectures. The control component controls a motor that drives the collecting net to move, thereby conveying the fluffy fiber network 55 outside the spinning chamber 20.

[0112] Please see Figure 6 As shown, the collecting net 48 has evenly distributed holes with a size of 0.5 to 3 mm. The shape of the holes is selected from one or more combinations of circles, triangles, squares, and rhombuses.

[0113] Please see Figure 6 As shown, the negative pressure plate 57 is a cuboid with a height of 1 to 2.5 cm. Circular holes are evenly distributed at the upper end of the negative pressure plate 57, with a diameter of 2 to 5 mm. An air intake 56 is opened at the lower end of the negative pressure plate 57, which is connected to the suction assembly b49 through a pipe.

[0114] Please see Figure 6As shown, the width of the collecting net 48 and the diameter of the cylindrical baffle 54 are (1~1.2):1, and the distance between the lower end of the cylindrical baffle 54 and the collecting net 48 is 20~80cm.

[0115] Please see Figure 6 As shown, the winding device 61 is equipped with a collecting roller 62.

[0116] Please see Figure 6 As shown, the heating length range of the heating box 62 is 1 to 6 m, and the maximum heating temperature of the heating box is 300°C; the maximum heating temperature of the hot pressing roller is 150°C, the speed is 5 to 15 m / min, and the distance between the hot pressing rollers is 0.05 to 1.5 mm.

[0117] Please see Figure 6 As shown, the distance between the right end of the heating box 58 and the hot pressing roller 59 is 10-50cm, the distance between the hot pressing roller 59 and the guide roller 60 is 30-80cm, and the distance between the guide roller 60 and the collecting roller 62 is 10-40cm.

[0118] Please see Figure 6 As shown, the specific process for continuously preparing micro / nanofiber nonwoven fabrics using a continuous supercritical fluid spinning system according to this embodiment includes the following steps:

[0119] First, a supercritical fluid spinning solution is prepared using reactor a, with all valves initially closed. Open the feed port 7 of the reactor and add high-density polyethylene. Close the feed port 7 and then slowly open the ring-shaped rotary shaft 2, setting the speed to 300 rad / min and stirring slowly. At the same time, turn on the cooling and heating mechanism 4, set the temperature to 100℃, and use an oil bath for heating, while applying a certain pressure to the raw materials to provide a basis for rapid and complete dissolution. During this period, adjust the temperature and pressure in real time according to the temperature and pressure sensor 5 displayed by the external control center. Open valves C12 and F15, and turn on the vacuum mechanism 9. After vacuuming is completed, close valves C12 and F15, and add 1,2-dichloromethane and cyclopentane in sequence. Open valve A10 and use the metering pump 3 to control the amount of solvent added. After injection, close valve A10. Open valves C12 and E14, and turn on the pressurization mechanism 6 to supplement the pressure of the reactor. Use nitrogen to pressurize and maintain the pressure at 12 MPa. Adjust the stirring speed to 600 rad / min and heat the temperature to 240℃ for 2 hours. Simultaneously, the spinning solution in reactor b can be prepared. After the spinning solution in reactor a is used up, the spinning solution in reactor b can be used directly, thereby achieving continuous production.

[0120] Then, open the suction assembly a40, cooling assembly a41, and cooling assembly b42 to make the temperature of condenser a38 approximately 20°C and the temperature of condenser b39 approximately 5°C; simultaneously, open the heating assembly 45, set the temperature to 60°C, and turn on the air compression assembly 44, controlling the regulating valve 2 to make the compressed air flow rate approximately 8000 m / min; at the same time, open valve g16 and flow regulating valve a21 to introduce the prepared supercritical fluid spinning solution into the high-pressure chamber 30. When the pressure in the high-pressure chamber 30 is 12 MPa, quickly open the flow regulating valve b25. When the pressure in the low-pressure chamber 33 is 8 MPa, open the flow regulating valve c35 to start spinning. When the spinning solution is ejected from the spinneret 361, the solvent rapidly expands into a gas. Simultaneously, the solvent recovery mechanism separates and recovers 1,2-dichloromethane and cyclopentane for reuse. The extremely fine fiber bundle 50 passes through the heating assembly and then through a high-pressure airflow zone. Under the action of the high-pressure airflow, the fibers are evenly separated. Due to the speed difference between the fibers, the fibers undergo secondary stretching, further refining them. After passing through the high-pressure airflow zone, the negative pressure adsorbs the high-speed moving fibers, preventing them from scattering and causing them to be evenly deposited on the collection net to form a fluffy fiber network 55. The fluffy fiber network 55 is then transported outside the spinning chamber 20 by a conveying mechanism and introduced into the heating box 58 to soften the fibers in the fluffy fiber network 55. The softened fluffy fiber network 55 is then rolled by a hot press roller 59 to form a nonwoven fabric. The nonwoven fabric then passes through a guide roller 60 and is finally collected by a winding device 61. The high-pressure chamber 30 has a volume of 100ml, the low-pressure chamber 33 has a volume of 80ml, and the temperature of the high-pressure chamber 30 and the low-pressure chamber 33 is 220℃; the spinning plate 36 has 15 spinnerets.

[0121] The above description of the embodiments is provided to enable those skilled in the art to understand and use the invention. It will be apparent to those skilled in the art that various modifications can be made to these embodiments, and the general principles described herein can be applied to other embodiments without inventive effort. Therefore, the present invention is not limited to the above embodiments, and any improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the invention should be within the protection scope of the present invention.

Claims

1. A continuous supercritical fluid spinning system for the continuous preparation of micro / nanofiber nonwoven fabrics, characterized in that, The continuous supercritical fluid spinning system includes a supercritical fluid spinning solution preparation device, a micro / nanofiber supercritical spinning device, and a micro / nanofiber secondary stretching and bundling collection device. The supercritical fluid spinning solution preparation device is connected to the micro / nano fiber supercritical spinning device. The supercritical spinning device for micro and nanofibers is located above the secondary stretching and bundling collection device for micro and nanofibers. The supercritical fluid spinning solution preparation device is used to continuously prepare uniform and stable supercritical fluid spinning solutions. The supercritical spinning device for micro and nanofibers is used to prepare uniform and continuous micro and nanofibers. The secondary drawing and bundling device for micro and nanofibers is used for bundling and collecting micro and nanofibers in a secondary drawing machine. The supercritical spinning device for micro and nanofibers includes a spinning chamber (20), a high-pressure chamber (30) and a low-pressure chamber (33) disposed in the spinning chamber (20), a solvent outlet (37) disposed on the side of the spinning chamber (20), and a solvent recovery mechanism connected to the solvent outlet (37). The high-pressure chamber (30) is equipped with a sensor a (22), a fluid inlet a (23) and a safety valve a (29) at the top, a fluid outlet a (24) at the bottom, and a heating and insulation mechanism a (31) outside the high-pressure chamber (30). The fluid inlet a (23) is connected to a high-temperature and high-pressure resistant pipeline, and a flow regulating valve a (21) is provided on the pipeline. The fluid outlet a (24) is connected to a high-temperature and high-pressure resistant pipeline, and a flow regulating valve b (25) is installed on the pipeline. The low-pressure chamber (33) has the same structure and configuration as the high-pressure chamber (30). The top of the low-pressure chamber (33) is provided with a sensor b (26), a fluid inlet b (27) and a safety valve b (32). The bottom of the low-pressure chamber (33) is provided with a fluid outlet b (28). The exterior of the low-pressure chamber (33) is provided with a heating and insulation mechanism b (34). The high-pressure chamber (30) and the low-pressure chamber (33) are connected by a pipe. The low-pressure chamber (33) is connected to the spinning plate (36) by a pipe, and a flow regulating valve c (35) is provided on the pipe. The flow regulating valves a (21), b (25), and c (35) are connected to the control panel (18); The sensors a (22) and b (26) are connected to the display screen (19); The secondary stretching and bundling device for the micro-nano fibers includes a spinning plate (36) in the spinning chamber (20), a fiber opening mechanism below the spinning plate (36), a conveying mechanism below the fiber opening mechanism, a negative pressure plate (57) in the conveying mechanism, a heating box (58), a hot press roller (59), a guide roller (60), and a winding device (61) on one side of the conveying mechanism. The fiber opening mechanism includes a heating component (45), a horn-shaped baffle a (51), an air outlet component (52), a horn-shaped baffle b (53), and a cylindrical baffle (54) arranged sequentially from top to bottom. The heating component (45) is cylindrical in shape, and the heating temperature range of the heating component (45) is 50~200℃; the heating method of the heating component (45) is one of infrared heating, electromagnetic heating, and resistance heating. The air outlet assembly (52) is cylindrical in shape and has a gap inside. A compressed air outlet (47) is installed at the gap of the air outlet assembly (52). The compressed air inlet (46) is connected to the air compression assembly (44) through a pipe, and a regulating valve (43) is installed on the pipe to regulate the gas flow rate. The internal gap of the air outlet assembly (52) is annular in shape and has a gap diameter of 1~4mm; the lower end diameter of the compressed air outlet (47) is 2~8mm; By using a flow regulating valve to precisely control the pressure in the high-pressure chamber, low-pressure chamber, and spinning plate, unstable liquid supply caused by pressure fluctuations is avoided. In conjunction with the use of a safety valve, excessive pressure is prevented from causing danger, thereby achieving a safe and stable supply of spinning solution. By placing the heating element below the spinning plate, the fiber bundle passes through the heating element, which facilitates further solvent removal.

2. The continuous supercritical fluid spinning system according to claim 1, characterized in that, The supercritical fluid spinning solution preparation device includes two reactors (1), which are connected by multiple pipes. The reactor (1) is equipped with an outer cooling and heating mechanism (4), an internal temperature and pressure sensor (5), a polymer feed port (7), and a pressure relief valve (8). The supercritical fluid spinning solution preparation device also includes a ring-shaped three-dimensional rotating shaft (2) that runs through the inside of the reactor (1), and the ring-shaped three-dimensional rotating shaft (2) contains two double helical blades of unequal size; The two reactors (1) share a metering pump (3), which is located on the first pipe connecting the two reactors (1); The second pipe connecting the double reactor (1) is connected to the pressurizing mechanism (6) and the vacuuming mechanism (9).

3. The continuous supercritical fluid spinning system according to claim 2, characterized in that, The supercritical fluid spinning solution preparation device and the micro / nano fiber supercritical spinning device are connected by a third pipe connecting the double reactor (1).

4. The continuous supercritical fluid spinning system according to claim 1, characterized in that, The solvent recovery mechanism includes condenser a (38), condenser b (39), suction assembly a (40), refrigeration assembly a (41) and refrigeration assembly b (42). The solvent outlet (37) is connected to the lower port of condenser a (38) through a pipe, the upper port of condenser a (38) is connected to the lower port of condenser b (39) through a pipe, and the upper port of condenser b (39) is connected to suction assembly a (40) through a pipe; the refrigeration assembly a (41) is connected to condenser b (39) through a pipe, and the refrigeration assembly b (42) is connected to condenser a (38) through a pipe.

5. The continuous supercritical fluid spinning system according to claim 1, characterized in that, The conveying mechanism includes a collection net (48), a motor, and a control component; The lower end of the negative pressure plate (57) has an air inlet (56), which is connected to the suction assembly b (49) through a pipe.

6. The continuous supercritical fluid spinning system according to claim 1, characterized in that, The spinning plate (36) has spinneret holes (361) distributed on it. The spinneret (361) is in the shape of a cylindrical cone, and the number of spinnerets (361) is 5 to 20.

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