CN103451754A - Differential melt electro-blowing spinning device and technology for preparing nanofibers in batches - Google Patents

Abstract

The invention discloses a melt differential electrospray spinning device and process for preparing nanofibers in batches, and belongs to the field of electrospinning. It mainly includes extruder, filter screen, melt metering pump, spinning box, air heating device, air compressor, upper electrode plate, lower electrode plate, high-voltage electrostatic generator, guide air knife, hot rolling device, receiving device , Laying belt and exhaust system, the outlet of the extruder is connected to the filter screen, and the melt metering pump is connected between the filter screen and the inlet of the spinning box through a flange, and the air flow is divided into two strands through the splitter device and connected to the spinning box After the melt passes through the spinning box, a thin layer of uniform flow melt layer is obtained at the lower end of the wave deflector. Under the action of high-voltage static electricity, the melt layer self-organizes to form multiple Taylor cones. Taylor cones are in high-speed airflow and Continue stretching and splitting under high-voltage static electricity, and solidify at the receiving end of the laying belt to form ultrafine fibers. The invention overcomes the difficulties of high polymer viscosity, low output, and complicated devices, and can realize the industrial production of melt differential electrospinning.

Description

A melt differential electrospray spinning device and process for preparing nanofibers in batches

technical field

The invention relates to a melt differential electrospray spinning device and process for preparing nanofibers in batches, and belongs to the field of electrospinning.

Background technique

The melt-blown spinning process is a process in which a high-speed hot air flow is used to draw a thin stream of polymer melt extruded from the spinneret hole of the spinning box, thereby forming ultra-fine fibers and collecting them on the condensation screen or roller; The melt differential electrospinning process is to apply a high-voltage electrostatic field between the differential nozzle and the receiving device, so that the polarized polymer melt overcomes the surface tension under the action of the electric field force, forms a jet on the end face of the differential nozzle, and flows on the receiving plate. The process of obtaining microfiber. The differential nozzle means that the nozzle evenly subdivides the melt, and the melt is firstly distributed through the flow channel, and then evenly divided into multiple strands by the nozzle, and the diameter of each filament reaches micron or nanometer. The electro-blowing spinning method combines the two processes of melt-blown spinning and electrospinning at the same time, and applies high-speed airflow stretching force and high-voltage electrostatic stretching force to the charged or polarized polymer melt. , to overcome the surface tension of the melt to form a high-speed jet, after high-power refinement, cooling and solidification, the process of forming a superfine fiber random deposition film or felt on the laying belt or receiving electrode.

Generally, fibers with an average diameter of 2-5 μm can be prepared by the melt-blown spinning process. The fibers are generally short fibers with a length of less than 100 mm, and the surface is rough. However, this process has considerable spinning efficiency, and the output of a spinneret can reach 3-5 μm. 10g/min; while the melt differential electrospinning process can produce fibers with an average diameter of 200nm-10μm. The fibers are continuous long fibers with controllable diameter and smooth surface, although the spinning efficiency of this process is 5-5% of that of ordinary capillary spinning. 20 times, but still an order of magnitude lower than the meltblown process. Therefore, through the innovative design of the device and process optimization, the meltblown process and the electrospinning process are combined to realize electrospray spinning, which is conducive to the development of submicron fiber preparation technology with ultra-high spinning efficiency, thus breaking through the conventional method of thicker fibers or higher efficiency. low problem.

In response to this problem, Eduard Zhmayev of Cornell University and others studied the process of single fiber thinning assisted by airflow, and found that the increase of high-speed airflow made the fiber thinner by 20 times, and applied for and obtained the US patent authorization accordingly (patent Publication number: US2013/0040140A1). Since there is no batch design scheme, the invention lacks practicability, and Benjamin Chu et al. of New York University applied for a patent on the spinning device and process combined with melt blown and electrostatic (patent publication number: US7887311B2), but the patent only revolves around The technical scheme of the nozzle device assembled with multiple capillaries and the nozzle melt cleaning device lacks a specific embodiment of melt electrospinning.

Some foreign companies have made breakthroughs in obtaining sub-micron fibers by melt-blown spinning. Hills has done in-depth research on nano-melt-blown fibers and has reached the stage of industrialization. Some other companies such as Nonwoven Technologies (NTI) have also developed the process and technology of nano-melt-blown fibers that can be produced, and have obtained patents. However, the melt blown technology of these companies is based on their extremely harsh preparation process and mold materials, and to a certain extent, the spinning efficiency is sacrificed. By assembling more spinning boxes to achieve a certain spinning efficiency, it greatly increases Equipment cost and maintenance cost.

Therefore, the present invention will realize the ingenious combination of ordinary melt blown process and melt differential electrospinning process through device design and process setting, and form a melt differential electrospray spinning method, which will become a low-cost and high-efficiency nanofiber preparation method. New options for industrialized devices and processes.

Contents of the invention

The invention proposes a melt differential electrospray spinning device and process for preparing nanofibers in batches. After the polymer melt passes through the hanger-shaped splitter plate, a thin-layer uniform flow melt is obtained. After the melt enters the slit of the splint holding the wave-shaped deflector, it is subjected to high-voltage electrostatic action at the lower end, and freely self-organizes to form multiple Taylor cones. , the Taylor cone continues to stretch and split under high-speed airflow and high-voltage static electricity, and forms a superfine fiber non-woven fabric at the receiving end of the web.

The technical solution adopted to achieve the above purpose is: a melt differential electrospray spinning device for preparing nanofibers in batches, which mainly includes an extruder, a filter screen, a melt metering pump, a spinning box, an air heating device, an air Press machine, upper electrode plate, lower electrode plate, high-voltage electrostatic generator, guide air knife, hot rolling device, receiving device, laying belt and exhaust system, extruder outlet connected to filter screen, filter screen and spinning box inlet The melt metering pump is connected through the flange, the outlet of the air compressor is connected to the airflow heating device, and then divided into two airflows through the splitter device and connected to the spinning box, the upper electrode plate is placed under the spinning box, and the distance from the upper electrode The lower electrode plate is placed at a certain distance from the plate, the mesh belt passes between the upper electrode plate and the lower electrode plate and sticks to the lower electrode plate, and the guide air knife is installed between the spinning box and the upper electrode plate, and the exhaust device is close to the directly below the lower electrode plate.

The present invention is a melt differential electrospray spinning device for preparing nanofibers in batches, wherein the spinning box is mainly composed of a hanger-type diverter plate, a transition plate, a waveform guide plate and a guide plate splint, and the hanger-type diverter plate, transition plate The plates and deflector splints are connected by screws, and after combination, a special-shaped cross-section air channel is formed.

The present invention is a melt differential electrospray spinning device for preparing nanofibers in batches, wherein the corrugated deflector is sandwiched between the deflector splints, and the section of the wave-shaped deflector is a wave curve, and its waveform can be a sine wave or a rectangle wave, realize the segmentation and diversion of the melt, and avoid the complexity of micro-hole processing with a large aspect ratio. The left and right ends of the wave deflector are welded with wedge-shaped blocks. The flow plate splint adjusts the gap between the splints, thereby compressing the wave deflector. At the same time, the adjustment spring connected to the wedge block provides pre-tightening force to ensure the sealing of the wedge block and the wedge surface of the deflector splint. Install the spring pressure plate of the adjustment spring The adjustment screw is connected with the splint of the deflector to ensure that the adjustment of the splint of the deflector is not affected.

The invention is a melt differential electrospray spinning device for preparing nanofibers in batches. The generation of high-voltage static electricity adopts a double-electrode design, that is, the upper electrode plate is placed between the spinning box and the laying belt, and the upper electrode plate and the wave guide Open a 30-100mm long linear through hole at the position facing the flow plate, and connect the high-voltage output end of the high-voltage electrostatic generator; the lower electrode plate is placed 0.2-5cm directly below the laying belt, and the lower electrode plate is evenly drilled 10- The 200-mesh fine holes are evenly distributed, which is convenient for the airflow of the ventilation system to pass through smoothly. The spinning box is grounded, the upper electrode plate is 2-8cm away from the lower end of the spinning box, the voltage of the upper electrode plate is 10-60kv, the lower electrode plate is 5-45cm away from the upper electrode plate, and the voltage is 20-160kv.

The invention is a melt differential electrospray spinning device for preparing nanofibers in batches. Guiding air knives are installed on the left and right sides above the upper electrode plate to guide the airflow to pass through the upper electrode plate smoothly, and at the same time produce a drafting and thinning effect on the fibers. The air velocity of the air knife can be adjusted within 10-100m/s, and the air temperature can be adjusted from -5 to 160°C.

The spinning process steps of a melt differential electrospray spinning device for preparing nanofibers in batches according to the present invention are as follows: first, preheat the extruder, spinning box, hot rolling device, etc. to the set temperature; The wire speed starts to extrude until the melt extrusion pressure is stable; the upper electrode plate and the lower electrode plate are powered on successively; after the uniform jet flow of the polymer melt appears, the air compressor air supply, air heating device and exhaust are turned on according to the preset parameters System; after the spinning process is stable, the mesh belt starts to run, and the non-woven fabric is wound up by the winding roller through the hot rolling device.

The invention discloses a melt differential electrospray spinning device and process for preparing nanofibers in batches. Since the structure of the traditional electrospinning capillary is changed, the electrospinning is changed from a single filament output method to utilizing rows of corrugated sheets. Guided into self-organized multiple Taylor cones arranged in a straight line, and then using high-speed airflow and high-voltage electric field, the batch preparation of polymer nanofibers with an average diameter of 200-800nm is realized, making the preparation efficiency close to industrial production. Spraying technology provides a material basis and technical support for the preparation of ultrafine fibers in my country and their applications in high-efficiency filtration, lithium battery diaphragms, and medical materials. It can overcome the difficulties of polymer high viscosity, low output, complicated device, etc., and realize the industrialized production of melt differential electrospinning.

Description of drawings

Figure 1 is a schematic diagram of the overall assembly of a melt differential electrospray spinning device for preparing nanofibers in batches according to the present invention.

Fig. 2 is a schematic cross-sectional view of a spinning box of a melt differential electrospray spinning device for batch production of nanofibers shown in Fig. 1 .

Fig. 3 is a schematic cross-sectional view of the hanger-type splitter plate in the spinning box shown in Fig. 2 .

Fig. 4 is a schematic isometric view of the baffle plate in the spinning beam shown in Fig. 2 .

Fig. 5 is a front view of the deflector splint in the spinning beam shown in Fig. 2 .

Fig. 6 is a schematic isometric view of the wave deflector shown in Fig. 4 and Fig. 5 .

Fig. 7 is a schematic cross-sectional view of the guide air knife shown in Fig. 1 .

In the figure: 1-extruder; 2-filter; 3-melt metering pump; 4-spinning box; 5-air heating device; 6-air compressor; 7-upper electrode plate; 8-lower electrode Plate; 9-high-voltage electrostatic generator; 10-guide air knife; 11-hot rolling device; 12-winding roller; 13-laying belt; 14-ventilation system; 17-wave deflector; 18-deflector splint; 19-air flow channel; 20-screw; 21-adjusting spring; 22-adjusting screw; 23-spring bearing plate; 24-wedge block; 25-set screw .

Detailed ways

The present invention is a melt differential electrospray spinning device for preparing nanofibers in batches, as shown in the schematic diagrams shown in Figures 1 to 7, the spinning device mainly includes an extruder 1, a filter screen 2, a melt metering pump 3, a spinning Box 4, airflow heating device 5, air compressor 6, upper electrode plate 7, lower electrode plate 8, high-voltage electrostatic generator 9, guide air knife 10, hot rolling device 11, winding roller 12, mesh belt 13 and Exhaust system 14, the outlet of extruder 1 is connected to the filter screen 2, the melt metering pump 3 is connected through the flange between the filter screen 2 and the inlet of the spinning box 4, the outlet of the air compressor 6 is connected to the airflow heating device 5, and then through the split flow The device is divided into two pipelines, connected to the spinning box 4, the upper electrode plate 7 is placed under the spinning box 4, the lower electrode plate 8 is placed at a certain distance below the upper electrode plate 7, and the mesh belt 13 passes through the upper electrode plate 7. Between the electrode plate 7 and the lower electrode plate 8 and close to the lower electrode plate 8, a guide air knife 10 is installed between the spinning box 4 and the upper electrode plate 7, and the exhaust system 14 is close to the bottom of the lower electrode plate 8, wherein The spinning box 4 is mainly composed of a hanger type diverter plate 15, a transition plate 16, a wave deflector plate 17 and a deflector splint 18, and the hanger type diverter plate 15, the transition plate 16 and the deflector splint 18 are all connected by screws 20 After the combination, the curved flow channel 19 is formed, the wave deflector 17 is clamped in the middle of the deflector splint 18, the left and right ends of the wave deflector 17 are welded with wedge blocks 24, and the adjustment spring 21 connected with the wedge block 24 provides The pre-tightening force ensures the sealing between the wedge block 24 and the wedge-shaped surface of the deflector splint. The spring-loaded spring bearing plate 23 is connected to the deflector splint 18 through the adjustment screw 22 to ensure that the adjustment of the deflector splint is not affected. Hanger type The splitter plate 15 has a symmetrical structure and is assembled by set screws 25 .

The process steps of a melt differential electrospray spinning process for preparing nanofibers in batches according to the present invention are as follows: extruder 1, spinning box 4, hot rolling device 11, etc. are preheated to the set temperature; start according to the preset spinning speed Extrude until the melt extrusion pressure is stable; the upper electrode plate 7 and the lower electrode plate 8 are energized successively through the high-voltage terminal of the high-voltage electrostatic generator 9; after the uniform jet flow of the polymer melt at the lower end of the wave deflector 17 appears, follow the preset Parameters Turn on the airflow supply of the air compressor 6, the airflow heating device 5 and the exhaust system 14; after the spinning process is stable, the web laying operation is started, and the non-woven fabric is wound up by the hot rolling device 11 with the winding roller 12.

An embodiment is shown in Fig. 1, 2, 5, and extruder 1 adopts screw rod diameter to be 65mm, and filter screen 2 is 240 orders, and spinning box body 4 widths are 1m, and corrugated deflector 17 is a sine wave deflector, plate The thickness is 1mm, the width from the peak to the trough is 3.5mm, the gap between the deflector splints is adjusted to 2mm by adjusting the spring 21 and the adjusting screw 22, the air flow of the air compressor 6 is 500m ³ /h, and the spinning material is pp6820 (melt flow rate 2000g /10min), the temperature of the melt metering pump 3 is set to 185°C, the temperature of the spinning box flow path is 230°C, the set temperature of the splint 18 and the deflector 17 is 260°C, the air velocity is 150m-200m/s, and the airflow is heated The temperature of the device 5 is set at 280°C, the distance between the upper electrode plate 7 and the spinning box is 50mm, the voltage is 30Kv, the distance between the upper electrode plate 7 and the lower electrode plate 8 is 400mm, the voltage of the lower electrode plate 8 is 65Kv, and the airflow speed of the guide air knife 10 is 80m/ s, the temperature is 80°C, the melt flow rate is 0.4Kg/min, and filaments below 1 micron can be obtained in batches.

Claims (6)

1. a batch prepares the melt differential EFI device for spinning of nanofiber, it is characterized in that: mainly comprise extruder, filter screen, melt metering pump, spinning manifold, airflow heating device, air compressor machine, electric pole plate, lower electrode plate, HV generator, the guiding air knife, hot-rolling arrangement, receiving system, lapping band and exhausting system, outlet of extruder connects filter screen, connect melt metering pump by flange between filter screen and spinning manifold entrance, the air compressor machine outlet connects airflow heating device, air-flow is divided into two strands by part flow arrangement and is switched to spinning manifold, spinning manifold positioned beneath electric pole plate, settle lower electrode plate apart from electric pole plate a distance, the lapping band passes between electric pole plate and lower electrode plate and is pasting lower electrode plate, the guiding air knife is installed between spinning manifold and electric pole plate, extractor fan is close under lower electrode plate, spinning manifold mainly is comprised of clothes hanger type flow distribution plate, rebound, waveform deflector and deflector clamping plate, clothes hanger type flow distribution plate, rebound and deflector clamping plate all are connected by screw, and after clothes hanger type flow distribution plate, rebound and the combination of deflector clamping plate, form the profiled-cross-section flow channel, the waveform deflector is clipped in the middle of the deflector clamping plate, corrugated deflector cross section curve in wave shape, two ends, the left and right welding wedge of waveform deflector, the waveform deflector has elasticity, adjust the clamping plate gap by clamping the deflector clamping plate, wedge is connected with regulating spring, electric pole plate and waveform deflector over against position open rectangular linear through hole, lower electrode plate is located under being placed in the lapping band, spinning manifold ground connection, electric pole plate all is connected the HV generator high-voltage output end with lower electrode plate.

2. a kind of batch according to claim 1 prepares the melt differential EFI device for spinning of nanofiber, and it is characterized in that: waveform is sine wave or square wave.

3. a kind of batch according to claim 1 prepares the melt differential EFI device for spinning of nanofiber, it is characterized in that: evenly bore 10-200 purpose hole on lower electrode plate.

4. a kind of batch according to claim 1 prepares the melt differential EFI device for spinning of nanofiber, and it is characterized in that: lower electrode plate is apart from electric pole plate 5-45cm.

5. a kind of batch according to claim 1 prepares the melt differential EFI device for spinning of nanofiber, it is characterized in that: the guiding air knife is installed in the left and right sides, electric pole plate top.

6. adopt a kind of batch claimed in claim 1 to prepare the spinning technique of the melt differential EFI device for spinning of nanofiber, it is characterized in that: first extruder, spinning manifold, hot-rolling arrangement etc. are preheating to design temperature; Start material extrusion until the melt extrusion pressure stability according to default spinning speed; Electric pole plate and lower electrode plate successively power up; After occurring, the uniform jet of polymer melt opens the supply of air compressor machine air-flow, airflow heating device and exhausting system according to parameter preset; After spinning process is stable, start the lapping tape running, nonwoven fabric utilizes the rolling of rolling roller by hot-rolling arrangement.

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