A continuous device for preparing two-dimensional nanofiber web composites

Abstract

This invention relates to a continuous apparatus for preparing two-dimensional nanofiber mesh composite materials, comprising a polymer solution spreading and film-forming mechanism, a segmented continuous freeze-drying mechanism, and a conveyor belt; wherein the polymer solution spreading and film-forming mechanism includes a solution infusion assembly, a droplet infusion assembly, and a substrate receiving assembly; the segmented continuous freeze-drying mechanism includes a self-segmentation assembly, a vacuum freeze-drying assembly, and a gas phase collection assembly. Compared with the prior art, the apparatus of this invention can realize the continuous large-area preparation of polymer liquid films and the controllable construction of two-dimensional mesh structures, solving the problems of excessively thick and uneven liquid films formed by existing coating technologies, and the uncontrollable and discontinuous mesh structures of existing two-dimensional nanofiber mesh materials. It can improve production efficiency and has great application potential in the field of separation and filtration.

Description

Technical Field

[0001] This invention relates to the field of material preparation apparatus, and in particular to a continuous apparatus for preparing two-dimensional nanofiber mesh composite materials. Background Technology

[0002] Fibrous materials are widely used in filtration and separation due to their small diameter, small pore size, and high porosity. However, the micron-sized diameter of fibrous materials makes it difficult to further reduce their pore size, limiting their practical applications. Post-processing fibrous substrates or combining them with materials with even smaller pore sizes can reduce the pore size of fibrous materials while retaining their original electrostatic adsorption properties and high mechanical properties.

[0003] Currently, some technicians have conducted relevant research. Patent CN201910719996.4 discloses "A Row of Hollow Fiber Nonwoven Composite Membrane and Its Preparation Method and Equipment," which involves preparing a substrate membrane using a substrate preparation device, then uniformly coating the outer surfaces of both sides of the substrate with a casting liquid using a coating device, solidifying it in a coagulation bath to form a membrane layer, and finally winding it with a take-up roller to obtain a row of hollow fiber nonwoven composite membrane. This coating device consists of a doctor blade, and the resulting liquid film thickness is too large, leading to uneven pore structure distribution after solidification and increased filtration resistance of the composite membrane. Patent CN201610384408.2 discloses "A Flat Multilayer Composite Membrane and Its Preparation Method," which uses a doctor blade that can be coated on both sides to coat a polyester nonwoven support layer, then immerses it in deionized water to separate the precipitated phase, obtaining a double-layer PEI porous substrate membrane. This method has a long water bath phase separation pore-forming time, the process is uncontrollable, and it cannot be continuously processed. Patent CN201810555559.9 discloses "A method for preparing interfacial thin-layer porous membranes using freeze-drying technology," which involves coating a liquid film onto a glass substrate using spin coating, followed by freeze-drying to obtain a thin-layer porous membrane. This method, which obtains the liquid film by spin coating on a glass substrate, suffers from the problem of uneven film formation due to surface tension, and the preparation method is discontinuous, making it difficult to prepare large-area porous membranes.

[0004] Therefore, there is an urgent need for a continuous fabrication device for small-pore nanofiber webs that can construct continuous ultrathin liquid films and control the phase separation process. Summary of the Invention

[0005] The purpose of this invention is to overcome the defects of the prior art by providing a continuous device for preparing two-dimensional nanofiber web composite materials. This continuous device can precisely control the liquid film thickness and realize the construction of an ultra-thin uniform liquid film on the electrospun substrate. It solves the problem of thick film formation and easy clogging of the original pore structure of the substrate in the traditional scraping coating process, improves production efficiency, and has great application potential in the field of separation and filtration.

[0006] The objective of this invention can be achieved through the following technical solutions:

[0007] The purpose of this invention is to provide a continuous apparatus for preparing two-dimensional nanofiber web composite materials, comprising a polymer solution spreading and film-forming mechanism, a segmented continuous freeze-drying mechanism, and a conveyor belt; the polymer solution spreading and film-forming mechanism includes a solution infusion assembly, a droplet injection assembly, and a receiving substrate assembly; the segmented continuous freeze-drying mechanism includes a self-cutting assembly, a vacuum freeze-drying assembly, and a gas phase collection assembly; the solution infusion assembly and the droplet injection assembly are materially connected; the solution infusion assembly and the droplet injection assembly are disposed above the receiving substrate assembly; the receiving substrate assembly, the self-cutting assembly, and the vacuum freeze-drying assembly are connected via the conveyor belt; the vacuum freeze-drying assembly... The air freeze-drying assembly and the gas phase collection assembly are connected by pipelines; the polymer solution in the solution filling assembly is dripped onto the surface of the fiber membrane substrate laid on the conveyor belt through the droplet injection assembly, and then a continuous polymer liquid film is formed. After the fiber membrane substrate with the polymer liquid film on its surface is pre-frozen and solidified by the receiving substrate assembly, it is cut into segments by the self-cutting assembly to obtain the material to be freeze-dried, and sent to the vacuum freeze-drying assembly for freeze-drying below the eutectic point of the polymer solution. Ice crystals grow to form a mesh structure, and then the ice crystals sublimate. The gas phase solvent and the liquefied gas phase solvent are collected separately by the gas phase collection assembly, and a two-dimensional nanofiber mesh composite material is obtained in the vacuum freeze-drying assembly.

[0008] Furthermore, the solution infusion assembly includes an upper fixed plate, a connecting screw, a lower fixed plate, a polymer solution stirring vessel, a control motor, a push rod, and a push plate; the push rod is built into the polymer solution stirring vessel; the lower end of the push rod is connected to the push plate; the push plate is clamped to the inner wall of the polymer solution stirring vessel, and the push plate serves to seal the internal air pressure; the polymer solution stirring vessel is fixed between the upper fixed plate and the lower fixed plate; the upper fixed plate and the lower fixed plate are connected by the connecting screw; the control motor is connected to the upper fixed plate; the output end of the control motor is connected to the push rod.

[0009] Furthermore, the solution filling assembly also includes a feed inlet and a stirring rod; the feed inlet is located on the propulsion plate; the stirring rod is disposed inside the polymer solution stirring vessel, and a stirring paddle is connected to the end of the stirring rod.

[0010] Furthermore, the liquid droplet infusion assembly includes an injection buffer tank, a micro heater, and an injection needle; the injection needle is connected to the injection buffer tank; the micro heater is located in the injection buffer tank and can heat the polymer solution in the injection buffer tank to reduce the surface tension of the polymer solution, thereby enabling the polymer solution to be rapidly injected into the injection needle.

[0011] Furthermore, the receiving substrate assembly includes a conveying roller, an infrared thickness sensor, a liquid nitrogen spray plate, and a liquid nitrogen tank; the infrared thickness sensor is located at the feeding end and the winding end of the fiber membrane substrate, and is used to detect the thickness and uniformity of the polymer liquid film formed on the substrate; the liquid nitrogen spray plate is located below the feeding end and the winding end of the fiber membrane substrate; the liquid nitrogen spray plate and the liquid nitrogen tank are connected by a pipe.

[0012] Furthermore, the self-cutting assembly includes a stand, a slide rail, a feed roller, and a cutter; the slide rail is mounted on the stand; the feed roller and the cutter are respectively connected to the slide rail, and the feed roller and the cutter can move freely up and down on the slide rail.

[0013] Furthermore, the vacuum freeze-drying assembly includes a cold drying chamber, a pressure roller, a refrigeration plate, a condensing pipe, a heat exchanger, a condenser, and a refrigeration compressor; the pressure roller and the refrigeration plate are disposed inside the cold drying chamber; the condensing pipe is disposed below the refrigeration plate, and the condensing pipe is sequentially connected to the heat exchanger, the condenser, and the refrigeration compressor; the pressure roller is disposed above the refrigeration plate, and the pressure roller is used to fix the fiber membrane substrate with a polymer liquid film attached to its surface.

[0014] Furthermore, the gas phase collection assembly includes a gas phase valve, a gas delivery pipeline, a gas storage tank, a stabilizing bracket, a gas-liquid separation valve, a liquid delivery pipeline, a vacuum valve, and a vacuum pump; the gas phase valve is connected to the gas delivery pipeline and is used to control the gas intake of the gas delivery pipeline; the gas delivery pipeline connects the vacuum freeze-drying assembly to the gas storage tank; the gas storage tank is equipped with the gas-liquid separation valve and the liquid delivery pipeline at its bottom; the gas storage tank is connected to the vacuum pump via a pipeline; the vacuum valve is located at the inlet of the vacuum pump; the stabilizing bracket is fixedly connected to the gas storage tank and is used to support the gas storage tank.

[0015] More preferably, in the solution infusion assembly, the infusion speed of the propulsion plate controlled by the control motor is 1 to 1000 mL / h.

[0016] More preferably, in the liquid droplet infusion assembly, the inner diameter of the injection needle is 0.1–5 mm, and the outer diameter is 0.3–5.3 mm; the dripping speed of the injection needle is 0.1–100 μl / s, and the liquid output volume is 1–50 μl.

[0017] More preferably, in the droplet injection assembly, the heating temperature of the micro heater in the injection buffer tank is 20-60°C, and the surface tension of the polymer solution in the injection buffer tank is 20-50 mN / m.

[0018] More preferably, in the receiving substrate assembly, the thickness detection range of the infrared thickness probe is 0.5 to 100 μm, and the uniformity detection deviation range is 60 to 100%.

[0019] More preferably, in the receiving substrate assembly, the flow rate of liquid nitrogen in the liquid nitrogen spray plate is 1-5 L / min, and the pre-freezing time is 10-30 min.

[0020] More preferably, in the self-cutting assembly, the feed roller speed is 0.5 to 2 m / min, and the cutting length is 50 to 80 cm.

[0021] More preferably, in the vacuum freeze-drying assembly, the pressure roller is made of one or more of stainless steel, iron, copper, iron oxide, and copper oxide; multiple pressure rollers are provided in the freeze-drying chamber, and the distance between adjacent pressure rollers is 60-100cm.

[0022] More preferably, in the vacuum freeze-drying assembly, the material to be freeze-dried is placed in the cold drying chamber for 30 to 60 hours of vacuum freeze-drying, at a temperature ≤ -50°C, and with a vacuum degree of -0.05 to -0.1 MPa.

[0023] More preferably, in the gas phase collection assembly, the capacity of the gas storage tank is 200-500L, and the opening interval of the gas-liquid separation valve is 24-72h.

[0024] More preferably, the cold drying box is provided with different processing layers.

[0025] The working principle of the continuous processing device for preparing two-dimensional nanofiber mesh composite materials is as follows: The polymer solution in the polymer solution stirring tank is injected through the push rod controlled by the control motor. The polymer solution enters the heated injection buffer tank, where the micro heater raises the temperature of the polymer solution, reduces its surface tension, and makes it easier to inject into the injection needle. The droplets generated by the micro-injection from the injection needle undergo superspreading on the surface of the fiber membrane substrate laid on the conveyor belt, dominated by capillary force. The polymer solution with low surface energy spontaneously superspreads on the fiber membrane substrate with high surface energy after pretreatment to form a continuous ultrathin liquid film. Subsequently, the fiber membrane substrate with the polymer liquid film on its surface is pre-frozen and solidified by liquid nitrogen spraying through the liquid nitrogen spray plate, and then cut into a suitable length by the cutter on the feed roller. The feed roller and the cutter can move freely up and down on the slide rail, which is fixed on the slidable upright. By sliding the feed roller and the cutter up and down and cutting the material into several pieces, the material to be freeze-dried is obtained. The polymer liquid film enters the cold drying box with its surface facing up and is fed into different processing layers of the cold drying box, thereby realizing large-scale preparation. The condenser cools the cooling plate in the cold drying box to below the eutectic point of the polymer solution through the refrigeration compressor. Ice crystals grow in the polymer liquid film to form a mesh structure. Then, the ice crystals sublimate in a vacuum ultra-low pressure environment. The gaseous solvent is drawn into the gas storage tank by the vacuum pump through the gas delivery pipe. After freeze-drying, a two-dimensional nanofiber mesh composite material is obtained. During the process of gradually returning to room temperature, the gaseous solvent liquefies and is discharged through the liquid delivery pipe.

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

[0027] 1) In the continuous device for preparing two-dimensional nanofiber web composite materials provided by this technical solution, the polymer solution spreading and film forming mechanism can precisely control the liquid film thickness, realize the construction of an ultra-thin and uniform liquid film on the electrospun substrate, and solve the problem of thick film formation and easy blockage of the original pore structure of the substrate in the traditional scraping coating process.

[0028] 2) The continuous device for preparing two-dimensional nanofiber composite materials provided in this technical solution produces two-dimensional nanofiber composite materials with small diameter and small pore size. The two-dimensional nanofibers are continuous structures that can cover a large area, giving the composite material good filtration performance and great application potential in the field of separation and filtration.

[0029] 3) The continuous equipment for preparing two-dimensional nanofiber mesh composite materials provided by this technical solution integrates liquid film spreading, substrate pre-freezing, automatic slicing and vacuum freeze drying into one unit, realizing the continuous large-area preparation of two-dimensional nanofiber mesh materials, saving time and costs and improving production efficiency. Attached Figure Description

[0030] Figure 1 This is a schematic diagram of a continuous fabrication device for preparing two-dimensional nanofiber mesh composite materials, as shown in the embodiment.

[0031] The numbers in the diagram are as follows:

[0032] 1. Upper fixing plate; 2. Connecting screw; 3. Lower fixing plate; 4. Control motor; 5. Conveyor roller; 6. Infrared thickness sensor; 7. Polymer solution stirring vessel; 8. Push rod; 9. Push plate; 10. Feed inlet; 11. Stirring rod; 12. Liquid injection buffer tank; 13. Miniature heater; 14. Liquid injection needle; 15. Liquid nitrogen spray plate; 16. Liquid nitrogen tank; 17. Stand; 18. Slide rail; 19. Feed roller; 20. Cutter; 21. Cold drying box; 22. Pressure roller; 23. Refrigeration plate; 24. Condensation pipe; 25. Heat exchanger; 26. Condenser; 27. Refrigeration compressor; 28. Gas phase valve; 29. ​​Gas delivery pipe; 30. Gas storage tank; 31. Stabilizing support; 32. Gas-liquid separation valve; 33. Liquid delivery pipe; 34. Vacuum valve; 35. Vacuum pump; 36. Conveyor belt. Detailed Implementation

[0033] 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.

[0034] In some preferred embodiments, in the solution infusion assembly, the infusion rate of the propulsion plate 9, controlled by the control motor 4, is 1 to 1000 mL / h.

[0035] In some preferred embodiments, in the liquid droplet infusion assembly, the inner diameter of the injection needle 14 is 0.1–5 mm, and the outer diameter is 0.3–5.3 mm; the dripping speed of the injection needle 14 is 0.1–100 μl / s, and the liquid output volume is 1–50 μl.

[0036] In some preferred embodiments, in the droplet infusion assembly, the heating temperature of the micro heater 13 in the injection buffer tank 12 is 20-60°C, and the surface tension of the polymer solution in the injection buffer tank 12 is 20-50 mN / m.

[0037] In some preferred embodiments, in the receiving substrate assembly, the thickness detection range of the infrared thickness probe 6 is 0.5 to 100 μm, and the uniformity detection deviation range is 60 to 100%.

[0038] In some preferred embodiments, in the receiving substrate assembly, the flow rate of liquid nitrogen in the liquid nitrogen spray plate 15 is 1-5 L / min, and the pre-freezing time is 10-30 min.

[0039] In some preferred embodiments, in the self-cutting assembly, the speed of the feed roller 19 is 0.5 to 2 m / min, and the cutting length is 50 to 80 cm.

[0040] In some preferred embodiments, the vacuum freeze-drying assembly uses one or more of the following materials: stainless steel, iron, copper, iron oxide, and copper oxide. Multiple pressure rollers 22 are provided inside the cold drying chamber 21, and the distance between adjacent pressure rollers 22 is 60-100 cm.

[0041] In some preferred embodiments, in the vacuum freeze-drying assembly, the material to be freeze-dried is placed in the cold drying chamber 21 for 30 to 60 hours of vacuum freeze-drying, at a temperature ≤ -50°C, and with a vacuum degree of -0.05 to -0.1 MPa.

[0042] In some preferred embodiments, in the gas phase collection assembly, the capacity of the gas storage tank 30 is 200-500L, and the opening interval of the gas-liquid separation valve 32 is 24-72h.

[0043] In some preferred embodiments, different processing layers are provided inside the cold drying box 21.

[0044] Example

[0045] like Figure 1As shown, this embodiment provides a continuous apparatus for preparing two-dimensional nanofiber mesh composite materials, including a polymer solution spreading and film-forming mechanism, a segmented continuous freeze-drying mechanism, and a conveyor belt 36; the polymer solution spreading and film-forming mechanism includes a solution infusion assembly, a droplet infusion assembly, and a receiving substrate assembly; the segmented continuous freeze-drying mechanism includes a self-cutting assembly, a vacuum freeze-drying assembly, and a gas phase collection assembly; the solution infusion assembly and the droplet infusion assembly are connected; the solution infusion assembly and the droplet infusion assembly are positioned above the receiving substrate assembly; the receiving substrate assembly, the self-cutting assembly, and the vacuum freeze-drying assembly are connected via the conveyor belt 36; the vacuum freeze-drying... The components and the gas phase collection component are connected by pipelines; the polymer solution in the solution infusion component is dripped onto the surface of the fiber membrane substrate laid on the conveyor belt 36 through the droplet infusion component, and then a continuous polymer liquid film is formed. After the fiber membrane substrate with the polymer liquid film on its surface is pre-frozen and solidified by the receiving substrate component, it is cut into segments by the self-cutting component to obtain the material to be freeze-dried, and sent to the vacuum freeze-drying component for freeze-drying below the eutectic point of the polymer solution. Ice crystals grow to form a mesh structure, and then the ice crystals sublimate. The gas phase solvent and the liquefied gas phase solvent are collected by the gas phase collection component respectively, and a two-dimensional nanofiber mesh composite material is obtained in the vacuum freeze-drying component.

[0046] The solution filling assembly includes an upper fixed plate 1, a connecting screw 2, a lower fixed plate 3, a polymer solution stirring vessel 7, a control motor 4, a push rod 8, a push plate 9, a feed inlet 10, and a stirring rod 11. The push rod 8 is built into the polymer solution stirring vessel 7. The lower end of the push rod 8 is connected to the push plate 9. The push plate 9 is clamped to the inner wall of the polymer solution stirring vessel 7 and serves to seal the internal air pressure. The polymer solution stirring vessel 7 is fixed between the upper fixed plate 1 and the lower fixed plate 3. The upper fixed plate 1 and the lower fixed plate 3 are connected by the connecting screw 2. The control motor 4 is connected to the upper fixed plate 1. The output end of the control motor 4 is connected to the push rod 8. The feed inlet 10 is opened on the push plate 9. The stirring rod 11 is located inside the polymer solution stirring vessel 7, and a stirring paddle is connected to the end of the stirring rod 11.

[0047] The liquid droplet injection assembly includes an injection buffer tank 12, a micro heater 13, and an injection needle 14. The injection buffer tank 12 is located at the bottom of the polymer solution stirring vessel 7, and the injection needle 14 is materially connected to the injection buffer tank 12. The solution in the polymer solution stirring vessel 7 can enter the injection needle 14 through the injection buffer tank 12. The micro heater 13 is located in the liquid buffer tank 12. The micro heater 13 can heat the polymer solution in the liquid buffer tank 12, reduce the surface tension of the polymer solution, and enable the polymer solution to be rapidly injected into the injection needle 14.

[0048] The receiving substrate assembly includes a conveying roller 5, an infrared thickness probe 6, a liquid nitrogen spray plate 15, and a liquid nitrogen tank 16. The infrared thickness probe 6 is located at the feeding end and the winding end of the fiber membrane substrate. The infrared thickness probe is a probe of an infrared thickness gauge. The probe has a preset thickness and uniformity detection range. When the thickness and uniformity of the liquid film reach the set range of the probe, the probes at both ends light up to indicate that the liquid film spreading process is completed and the liquid nitrogen pre-freezing process is carried out. The liquid nitrogen spray plate 15 is located below the feeding end and the winding end of the fiber membrane substrate. The liquid nitrogen spray plate 15 and the liquid nitrogen tank 16 are connected by a pipe.

[0049] The self-cutting assembly includes a stand 17, a slide rail 18, a feed roller 19, and a cutter 20. The slide rail 18 is mounted on the stand 17, which can slide on the ground. The feed roller 19 and the cutter 20 are connected to the slide rail 18, and can move freely up and down on the slide rail 18. The slide rail 18 is a linear grooved guide rail, and two freely movable sliders are provided in the groove, which are connected to the feed roller 19 and the cutter 20, respectively. The grooved guide rail has a positioning pin opening every 10cm, and the positioning pin can freely pass through the opening. When the slider moves, the positioning pin is pulled out. When the slider moves to the desired position, the positioning pin is inserted into the opening to limit the slider.

[0050] The vacuum freeze-drying assembly includes a cold drying chamber 21, a pressure roller 22, a cooling plate 23, a condensing pipe 24, a heat exchanger 25, a condenser 26, and a refrigeration compressor 27. The pressure roller 22 and the cooling plate 23 are located inside the cold drying chamber 21. The condensing pipe 24 is located below the cooling plate 23 and is connected in sequence to the heat exchanger 25, the condenser 26, and the refrigeration compressor 27. The pressure roller 22 is located above the cooling plate 23 and is used to fix the fiber membrane substrate with a polymer liquid film on its surface.

[0051] The gas phase collection assembly includes a gas phase valve 28, a gas delivery pipeline 29, a gas storage tank 30, a stabilizing bracket 31, a gas-liquid separation valve 32, a liquid delivery pipeline 33, a vacuum valve 34, and a vacuum pump 35. The gas phase valve 28 is connected to the gas delivery pipeline 29 and is used to control the gas intake of the gas delivery pipeline 29. The gas delivery pipeline 29 connects the vacuum freeze-drying assembly to the gas storage tank 30. The bottom of the gas storage tank 30 is equipped with a gas-liquid separation valve 32 and a liquid delivery pipeline 33. The gas storage tank 30 is connected to the vacuum pump 35 through a pipeline. The vacuum valve 34 is located at the gas inlet of the vacuum pump 35. The stabilizing bracket 31 is fixedly connected to the gas storage tank 30 and is used to support the gas storage tank 30.

[0052] The preparation steps of the two-dimensional nanofiber mesh composite material using the continuous processing device described above are as follows:

[0053] S1. Add 500g of N,N-dimethylformamide and 10g of polyacrylonitrile into polymer solution stirring tank 7 through feed port 10, and stir for 8h to obtain polymer solution;

[0054] S2. The polyamide electrospun nanofiber membrane substrate is fed into the conveyor roller 5. The push rod 8 is set on the control motor 4 and the injection speed is 50mL / h. An injection needle 14 with an inner diameter of 2mm and an outer diameter of 3.2mm is used. The dripping speed is 10μl / s and the liquid output volume is 10μl. The temperature of the micro heater 13 is 40℃. The polymer solution obtained in step S1 is dripped. The polymer liquid film is spread and a fiber membrane substrate with a polymer liquid film on the surface is obtained.

[0055] S3. After the polymer liquid film is spread, liquid nitrogen is injected into the liquid nitrogen spray plate 15 at a flow rate of 5L / min. The fiber membrane substrate with polymer liquid film on its surface obtained in step S2 is pre-frozen for 20min to obtain the pre-frozen substrate.

[0056] S4. The pre-frozen substrate obtained in step S3 is conveyed to the cooling plate 23 via the feeding roller 19 and cut into sections using the cutter 20. The pre-frozen substrate obtained in step S3 is fixed under the pressure roller 22. The feeding roller speed is set to 1m / min and the section length is 40cm. The feeding roller 19 and the cutter 20 move downwards via the slide rail 18 to feed the substrate into the second cooling plate. The above operation is repeated to obtain the material to be freeze-dried.

[0057] S5. Start the refrigeration compressor 27, gas phase valve 28, vacuum valve 34, and vacuum pump 35 to perform vacuum freeze-drying on the material to be freeze-dried obtained in step S4 in the cold drying box 21. The condenser 26 cools the refrigeration plate 23 to below the eutectic point of the polymer solution through the refrigeration compressor 27. Ice crystals grow in the polymer liquid film to form a mesh structure. Then, the ice crystals sublimate in a vacuum ultra-low pressure environment. The gas phase solvent is drawn into the gas storage tank 30 by the vacuum pump 35 through the gas delivery pipe 29. The vacuum freeze-drying time is 40 hours, the temperature is -70℃, and the vacuum degree is -0.1MPa. After the vacuum freeze-drying is completed, a two-dimensional nanofiber mesh composite material is obtained. The equipment is turned off, the gas-liquid separation valve 32 is opened, and the liquefied gas phase solvent is discharged through the liquid delivery pipe 33 for environmental protection treatment as it gradually returns to room temperature.

[0058] 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 device for preparing a two-dimensional nanofibril web composite material, characterized by, Includes a polymer solution spreading and film forming mechanism, a segmented continuous freeze-drying mechanism, and a conveyor belt (36). The polymer solution spreading and film forming mechanism includes a solution infusion assembly, a droplet infusion assembly, and a receiving substrate assembly; The segmented continuous freeze-drying mechanism includes a self-segmentation assembly, a vacuum freeze-drying assembly, and a gas phase collection assembly; The solution filling assembly and the droplet filling assembly are materially connected; the solution filling assembly and the droplet filling assembly are located above the receiving substrate assembly; the receiving substrate assembly, the self-cutting assembly and the vacuum freeze-drying assembly are connected by the conveyor belt (36); the vacuum freeze-drying assembly and the gas phase collection assembly are connected by pipelines; The polymer solution in the solution infusion assembly is dripped onto the surface of the fiber membrane substrate laid on the conveyor belt (36) through the droplet infusion assembly, and then a continuous polymer liquid film is formed. After the fiber membrane substrate with the polymer liquid film on its surface is pre-frozen and solidified by the receiving substrate assembly, it is cut into sections by the self-cutting assembly to obtain the material to be freeze-dried. It is then sent to the vacuum freeze-drying assembly for freeze-drying below the eutectic point of the polymer solution. Ice crystals grow to form a mesh structure. After the ice crystals sublimate, the gaseous solvent and the liquefied gaseous solvent are collected by the gas phase collection assembly respectively. A two-dimensional nanofiber mesh composite material is obtained in the vacuum freeze-drying assembly. The solution infusion assembly includes an upper fixed plate (1), a connecting screw (2), a lower fixed plate (3), a polymer solution stirring tank (7), a control motor (4), a push rod (8), and a push plate (9). The polymer solution stirring vessel (7) contains the push rod (8); the lower end of the push rod (8) is connected to the push plate (9); the push plate (9) is engaged with the inner wall of the polymer solution stirring vessel (7); the polymer solution stirring vessel (7) is fixed between the upper fixing plate (1) and the lower fixing plate (3); the upper fixing plate (1) and the lower fixing plate (3) are connected by the connecting screw (2); the control motor (4) is connected to the upper fixing plate (1); the output end of the control motor (4) is connected to the push rod (8); The droplet infusion assembly includes an infusion buffer tank (12), a micro heater (13), and an infusion needle (14). The injection needle (14) is connected to the injection buffer tank (12); the micro heater (13) is located in the injection buffer tank (12).

2. The continuous processing apparatus for preparing two-dimensional nanofiber web composite materials according to claim 1, characterized in that, The solution infusion assembly also includes an inlet (10) and a stirring rod (11). The feed inlet (10) is located on the push plate (9); the stirring rod (11) is located inside the polymer solution stirring tank (7), and a stirring paddle is connected to the end of the stirring rod (11).

3. The continuous processing apparatus for preparing two-dimensional nanofiber web composite materials according to claim 1, characterized in that, In the liquid droplet infusion assembly, the inner diameter of the injection needle (14) is 0.1~5mm and the outer diameter is 0.3~5.3mm; the dripping speed of the injection needle (14) is 0.1~100μl / s and the liquid output volume is 1~50μl.

4. The continuous processing apparatus for preparing two-dimensional nanofiber web composite materials according to claim 1, characterized in that, The receiving substrate assembly includes a conveyor roller (5), an infrared thickness probe (6), a liquid nitrogen spray plate (15), and a liquid nitrogen tank (16). The infrared thickness probe (6) is located at the feed end and the winding end of the fiber membrane substrate and can measure the thickness of the fiber membrane substrate; the liquid nitrogen spray plate (15) is located below the feed end and the winding end of the fiber membrane substrate; the liquid nitrogen spray plate (15) is connected to the liquid nitrogen tank (16).

5. The continuous processing apparatus for preparing two-dimensional nanofiber web composite materials according to claim 1, characterized in that, The self-cutting assembly includes a stand (17), a slide rail (18), a feed roller (19), and a cutter (20). The slide rail (18) is mounted on the upright frame (17); the feed roller (19) and the cutter (20) are respectively connected to the slide rail (18).

6. The continuous processing apparatus for preparing two-dimensional nanofiber web composite materials according to claim 1, characterized in that, The vacuum freeze-drying assembly includes a cold drying box (21), a pressure roller (22), a refrigeration plate (23), a condensation pipe (24), a heat exchanger (25), a condenser (26), and a refrigeration compressor (27). The pressure roller (22) and the refrigeration plate (23) are located inside the cold drying box (21); the condensation pipe (24) is located below the refrigeration plate (23), and the condensation pipe (24) is connected in sequence to the heat exchanger (25), the condenser (26), and the refrigeration compressor (27); the pressure roller (22) is located above the refrigeration plate (23).

7. The continuous processing apparatus for preparing two-dimensional nanofiber web composite materials according to claim 6, characterized in that, In the vacuum freeze-drying assembly, the pressure roller (22) is made of one or more of stainless steel, iron, copper, iron oxide, and copper oxide. Multiple pressure rollers (22) are provided inside the cold drying box (21), and the distance between adjacent pressure rollers (22) is 60~100cm.

8. The continuous processing apparatus for preparing two-dimensional nanofiber web composite materials according to claim 1, characterized in that, The gas phase collection assembly includes a gas phase valve (28), a gas delivery pipeline (29), a gas storage tank (30), a stabilizing support (31), a gas-liquid separation valve (32), a liquid delivery pipeline (33), a vacuum valve (34), and a vacuum pump (35). The gas phase valve (28) is connected to the gas delivery pipeline (29); the gas delivery pipeline (29) connects the vacuum freeze-drying assembly to the gas storage tank (30); the gas storage tank (30) is provided with the gas-liquid separation valve (32) and the liquid delivery pipeline (33) at the bottom; the gas storage tank (30) is connected to the vacuum pump (35); the vacuum valve (34) is located at the air inlet of the vacuum pump (35); the stabilizing bracket (31) is connected to the gas storage tank (30).

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