KR20220028258A - Filter production method using adjustment method of fiber shape and nanofiber diameter - Google Patents

Abstract

The present invention relates to a filter manufacturing method using a method for adjusting a fiber shape and a naonofiber diameter, and provides a filter manufacturing method which is performed by using a filter manufacturing device including: an electrospinning machine that spins a polymer solution to form fibers; a substrate that collects the fibers formed by the electrospinning machine; a support that supports the substrate; a flow diffuser that is installed inside the support; an ionizer that is installed on the support to provide ions having polarity opposite to that of the fiber; a multimeter that is connected to the substrate to measure currents of the fiber and ionizer; an air compressor that provides compressed air to the support; and a flow controller that controls a flow rate of the compressed air, and which includes: performing electrospinning by selecting a concentration of a specific polymer; adjusting a voltage applied during the electrospinning; and adjusting an amount of ions provided to the fibers collected on the substrate. According to the present invention, it is possible to manufacture a filter with a relatively low differential pressure and high efficiency.

Description

Filter production method using adjustment method of fiber shape and nanofiber diameter

The present invention relates to a filter manufacturing method, and more particularly, to a filter manufacturing method utilizing a fiber shape and nano fiber diameter control method.

In the conventional electrospinning method, there is a limit to the control of the fiber diameter. The reason is that, if the polymer concentration of the polymer solution to be spun during electrospinning does not exceed a certain value, a stable fiber form cannot be obtained. This is because it is not possible to obtain a thin fiber diameter.

It is an object of the present invention to provide a filter manufacturing method capable of obtaining a desired fiber shape and fiber diameter.

In order to achieve the above object, the present invention provides an electrospinning machine for spinning a polymer solution to form fibers, a substrate for collecting fibers formed from the electrospinning machine, a support for supporting the substrate, a flow disperser installed inside the support, a fiber installed on the support An ionizer that provides ions of polarity opposite to the polarity, a multimeter connected to the substrate to measure the current of the fiber and the ionizer, an air compressor that provides compressed air to the support, and a flow controller that controls the flow rate of compressed air performing electrospinning by using a filter manufacturing apparatus, selecting a specific polymer concentration; adjusting the applied voltage during electrospinning; It provides a filter manufacturing method comprising the step of adjusting the amount of ions provided to the fibers collected on the substrate.

In the present invention, the flow spreader is configured in the form of a plate, and may include a plurality of first holes disposed in the central region of the plate, and a plurality of second holes disposed in the outer region of the plate and having a larger diameter than the first hole. .

In the present invention, the polymer concentration may be selected within the range of 1 to 20 wt%.

In the present invention, the applied voltage can be adjusted in the range of 1 to 20 kV.

In the present invention, the amount of ions can be adjusted in the range of 1×10 ⁶ to 9.99×10 ⁸ cc.

In the present invention, the amount of ions can be adjusted by controlling the flow rate of compressed air.

In the present invention, the flow rate of compressed air can be adjusted in the range of 0.01 to 5 m/s.

In the present invention, the amount of ions can be adjusted so that the current value measured by the multimeter is within the range of ±100 nA.

In the present invention, the diameter of the fiber can be adjusted in the range of 10 to 500 nm.

In the present invention, even when the concentration of the polymer solution is 10% by weight or less, it is possible to produce a bead-free fiber.

In addition, the present invention is an electrospinning machine for spinning a polymer solution to form fibers; a substrate for collecting fibers formed from the electrospinning machine; a support for supporting the substrate; flow disperser installed inside the support; an ionizer installed on the support to provide ions of opposite polarity to the fiber polarity; a multimeter connected to the substrate to measure the current of the fiber and the ionizer; an air compressor for providing compressed air to the support; It provides a filter manufacturing apparatus including a flow controller for controlling the flow rate of compressed air.

The selected polymer (PAN, etc.) material is spun using electrospinning through the filter manufacturing apparatus according to the present invention, but at this time, the ion amount of the fiber neutralizing device installed on the side of the collecting unit that collects the spun fibers and the voltage applied during electrospinning By utilizing the control of and the control of the polymer concentration, the experimenter can obtain the desired fiber shape and fiber diameter.

By utilizing the technology of the present invention, it is possible to obtain a desired fiber shape and fiber diameter, as well as regardless of the concentration of the polymer. In addition, the range of the adjustable fiber diameter in the present technology is a slip effect in which the efficiency of the nanofiber filter is maximized, that is, the diameter of the fiber is close to 64 nm, which is the mean free path of air molecules. Since it includes a section showing the effect of maintaining a relatively low-differential pressure and high-efficiency when having , it is possible to manufacture a filter having a relatively low-differential pressure and high-efficiency.

The technology of the present invention has the advantage that the user can freely control the performance of the filter manufactured by adjusting the desired fiber shape, fiber diameter, and fiber spinning time. The technology of the present invention can be applied anywhere in which fibers are handled. In addition, the demand for high-efficiency fibers and filters is further increasing due to the corona virus in time, and since the current corona crisis can also change people's thinking and lifestyle, the technology of the present invention is also used in manufacturing fibers for masks. It is possible to use it, and accordingly, the marketability and expected effect are expected to be very large.

1 is a block diagram of a filter manufacturing apparatus according to the present invention.
Figure 2 is a block diagram of the support and flow disperser according to the present invention.
3 is a graph showing ion amount measurement data according to the air flow rate and the number of ionizers.
4 is a graph (left) and a scanning electron microscope (SEM) photograph showing the amount of beads according to the current value measured by the multimeter.
5 is a SEM photograph of nanofibers according to an applied voltage at a polyacrylonitrile (PAN) concentration of 7% by weight.
6 is a SEM photograph of nanofibers according to an applied voltage at a PAN concentration of 8 wt%.
7 is an SEM photograph of nanofibers according to an applied voltage at a PAN concentration of 9 wt%.

Hereinafter, the present invention will be described in detail.

1, the filter manufacturing apparatus according to the present invention is an electrospinning machine 10, a power source 20, a substrate 30, a support 40, an ionizer 50, a multimeter 60, an air compressor ( 70 ), a filter 80 , a regulator 90 , a flow controller 100 , a flow disperser 110 , and the like.

The electrospinning machine 10 serves to form fibers by spinning a polymer solution. The electric radiator 10 may include a power supply 20, a flow rate controller, and the like, and the power supply 20 may be a high voltage power supply. As the electrospun polymer, polyacrylonitrile (PAN), polyethylene oxide (PEO), polyvinylpyrrolidone (PVP), polymethyl methacrylate (PMMA), polyvinyl alcohol (PVA), etc. can be used, Preferably, polyacrylonitrile (PAN) may be used. As a solvent in the polymer solution, dimethylformamide (DMF), dimethylacetamide (DMAc), or the like can be used.

The substrate 30 serves to collect the fibers formed from the electrospinning machine 10 , that is, it may be a collector. The substrate 30 may be configured in the form of a mesh in which a plurality of holes are formed to allow air and ions to pass therethrough. The substrate 30 may be made of metal or the like. The fibers collected on the substrate 30 are uniformly stacked to form a filter. Compared with non-conductive substrates, in the case of conductive (metal, etc.) substrates, the charge of the fibers can be dissipated, thereby increasing the packing density.

1 and 2 , the support 40 serves to support the substrate 30 so that air and ions can be supplied. That is, the support 40 serves as an ion generation duct. The support 40 may be configured in a cylindrical (cylindrical, etc.) shape, and may be entirely sealed while only the upper portion on which the substrate 30 is disposed is opened. However, a hole for installing the ionizer 50 may be installed in the side surface of the support 40 . A flow path or tube through which air is introduced may be installed at a lower portion of the support 40 .

The ionizer 50 is installed on the support 40 and serves to provide ions having a polarity opposite to that of the fiber polarity. The fibers spun from the electrospinning machine 10 are negatively charged (-) or positively charged (+) by the electrospinning method, and when the fibers are piled up on the substrate 30 to some extent, a repulsive force is generated between the fibers. In order to manufacture a filter having excellent filtration performance, fine fibers are uniformly disposed on the substrate 30, and when a plurality of filters are stacked rather than one filter, the filtration performance is further improved. However, when the filter is manufactured with a device equipped with only the conventional electrospinning function, the fibers are laminated to the existing thickness on the substrate 30, but when the fibers are laminated to a thicker thickness, a repulsive force is generated between charged ions in the fibers, The fibers are not evenly distributed. In addition, as beads are generated in the fibers, a microscopic space is formed in the filter, or the filter performance is deteriorated because it is not densely arranged. Therefore, the charged fibers must be neutralized and laminated so that the fibers can be densely and uniformly arranged.

The ionizer 50 supplies ions having a polarity opposite to the polarity of the charged fibers to neutralize the fibers in which the repulsive force is generated, so that the fibers can be arranged thicker and more uniformly. For example, if the fiber has a positive charge, the ionizer 50 provides a negative charge, and if the fiber has a negative charge, the ionizer 50 provides a positive charge. Since the fiber spun by the electrospinning method has a polarity of negative charge (-) or positive charge (+) depending on the situation, so that ions of opposite polarity can be generated according to the polarity of the fiber, the ionizer 50 is the polarity of the ions It can be provided with means for selecting. In addition, the ionizer 50 may include a power supply capable of increasing or decreasing the amount of ions generated. When the amount of power of the power supply is increased, the amount of ions generated by the ionizer 50 increases, and when the amount of power is decreased, the amount of generated ions from the ionizer 50 decreases.

The ionizer 50 may be located on the side or lower side of the support 40 . The number of installed ionizers 50 will be sufficient as long as the number of ions capable of being neutralized to the extent that fibers are uniformly and not generated while fibers are stacked is sufficient. The number of the ionizer 50 may be one or a plurality, for example, 1 to 20, preferably 2 to 15, more preferably 3 to 10 may be. The ionizer 50 can be installed detachably from the support 40, and is made to be easily replaced or repaired when a failure occurs. On the other hand, when the ionizer 50 is used, it is possible to increase the reproducibility in the manufacture of ultra-fine nanofibers, and it may be advantageous to manufacture nanofibers with few or no beads.

A multimeter (60) is connected to the substrate and serves to measure the current of the fiber and the ionizer (50). In order for the fibers to be spun by the electrospinning machine 10 to be uniform and to improve filtration performance, the fibers must be thickly laminated, and in order to be thickly laminated over a certain thickness, the fibers must be neutralized. When spinning in the electrospinning machine 10, the charged fiber is not properly neutralized, or the ionizer 50 is supplied with too many ions so that the fiber is not charged with the opposite polarity, and the current value is as close to neutral (0) as possible. It can be laminated to the desired thickness. Accordingly, the multimeter 60 for measuring the current of the fiber spun by the electrospinning machine 10 and the ionizer 50 is connected to the substrate 30 to measure the current value in real time. That is, when fibers start to accumulate on the substrate 30 , the multimeter 60 measures the current value, and when the ionizer 50 is operated while looking at the multimeter 60 , the multimeter 60 connected to the substrate 30 ) is close to neutral. The range in which the current value measured by the multimeter 60 converges to neutral may be a current value between -100 nA and 100 nA. If fibers are laminated while maintaining this state, a filter of the desired thickness can be manufactured by the user.

The air compressor 70 serves to supply compressed air to the support 40 . To this end, an air tube may be connected from the air compressor 70 to the support 40 . The compressed air serves to transfer the ions formed from the ionizer 50 to the fiber. As the air compressor 70, a conventional air compressor may be used.

The filter 80 serves to remove foreign substances or contaminants contained in the compressed air supplied to the support 40 . The filter 80 may be installed at any position among the air tubes disposed between the air compressor 70 and the support 40 . Considering that air transfers ions to the fiber, a high efficiency particulate air (HEPA) filter or the like may be used as the filter 80 .

The regulator 90 serves to adjust the pressure of compressed air, and the like. The regulator 90 may be installed between the filter 80 and the support 40 .

The flow controller 100 serves to control the flow rate of compressed air. The flow controller 100 may be installed between the regulator 90 and the support 40 . As the flow controller, an MFC (Mass Flow Controller) may be used.

Referring to Figure 2, the flow spreader (Flow Spreader) 110 is installed inside the support 40 serves to distribute the air flow. The flow disperser 110 may be disposed on the lower side of the support 40 , may be configured in the form of a plate (disc, etc.), and may have the same diameter as the inner diameter of the support 40 . The flow spreader 110 includes a plurality of first holes 112 disposed in the central region of the plate, and a plurality of second holes 114 disposed in the outer region of the plate and having a larger diameter than the first hole 112 . can do. The diameter of the first hole 112 may be, for example, 0.5 to 2.5 mm, preferably 1 to 2 mm. The diameter of the second hole 114 may be, for example, 2.5 to 4.5 mm, preferably 3 to 4 mm. The diameter of the central region in which the plurality of first holes 112 are disposed may be, for example, 10 to 50% of the total diameter of the plate, and preferably 25 to 35%. This hole configuration makes it possible to more effectively and uniformly disperse the air flow to effectively and uniformly transfer ions to the fibers.

The filter manufacturing method according to the present invention includes the steps of using the above-described filter manufacturing apparatus and performing electrospinning by selecting a specific polymer concentration; adjusting the applied voltage during electrospinning; It may include adjusting the amount of ions provided to the fibers collected on the substrate. These steps may be performed sequentially or simultaneously.

First, electrospinning is performed by selecting a specific polymer concentration. The polymer concentration can be selected within the range of 1 to 20% by weight, preferably 3 to 15% by weight, more preferably 6 to 12% by weight. The polymer concentration may refer to the weight of the polymer relative to the volume of the polymer solution, that is, w/v%. In general, when the polymer concentration is low, the fiber diameter becomes thin, and when the polymer concentration is high, the fiber diameter becomes thick.

Next, the applied voltage is adjusted during electrospinning. The applied voltage can be adjusted in the range of 1 to 20 kV, preferably 3 to 15 kV, and more preferably 6 to 12 kV. In general, when the voltage is low, the fiber diameter becomes thick, and when the voltage is high, the fiber diameter becomes thin. In addition, the higher the voltage, the more neutral ions are generated and more beads may be formed.

Next, the amount of ions provided to the fibers collected on the substrate is adjusted. The amount of ions can be adjusted in the range of 1×10 ⁶ to 9.99×10 ⁸ cc (mL), preferably 5×10 ⁶ to 5×10 ⁸ cc, more preferably 1×10 ⁷ to 9×10 ⁷ cc. There is (see Fig. 3). In the case of an anion of an ion, a minus sign may be attached in front of the flow rate value, and in the case of a cation, a plus sign may be attached. The amount of ions can be appropriately adjusted so that fiber neutralization is well achieved.

It is preferable to adjust the amount of ions by controlling the flow rate of compressed air rather than controlling the ionizer 50 itself. In the case of simply using a fan driven through a battery, fine flow rate control is impossible, so there is a limitation in use in the actual process. In addition, when the supply flow rate is increased, the amount of ions is also increased by increasing the amount of air blown. In the present invention, the supply flow rate control is smooth, so that the ionizer 50 itself does not control the amount of ions, but changes the flow rate of air. Through this, it is possible to control the amount of ions and to release the constraints of the process (voltage, distance from the collector, and the amount of ions generated).

The flow rate (flow rate) of the compressed air can be adjusted in the range of 0.01 to 5 m/s, preferably 0.05 to 3 m/s, and more preferably 0.1 to 1 m/s. As shown in FIG. 3, the amount of ions can be varied and appropriately adjusted according to the air flow rate (refer to the upper flow rate in FIG. 3) and the number of ionizers (refer to the upper number in FIG. 3).

In particular, the amount of ions may be adjusted so that the current value measured by the multimeter 60 is within the range of ±100 nA, preferably ±70 nA, and more preferably ±50 nA. The most important part in the specific conditions of the process is the current measurement value of the fiber collector part using the multimeter 60. The closer to neutral, the more stable (bead-free or minimized) fiber can be obtained. In electrospinning, the applied voltage and experimental conditions may vary greatly depending on the influence of temperature and humidity, and the changing experimental conditions can be more easily met through the technique of the present invention.

Referring to FIG. 4 , when the current value measured by the multimeter is too small or too large with respect to 0, the amount of beads is rapidly increased. As can be seen from the SEM photos of FIGS. 4 to 7 , the bead may refer to a portion having a diameter much larger than the average diameter of the fiber in the longitudinal direction of the fiber, such as rice grain shape, bead shape, rod shape, and the like. The amount of beads can be evaluated through a method of calculating the number of beads in an SEM photograph. As the amount of beads decreases, a fiber having a stable fiber shape can be obtained.

Referring to the graph on the left of FIG. 4 , as the current value increased to the + side, the bead amount increased, and as the current value increased to the - side, the bead amount increased more rapidly than the + side. In particular, referring to the right SEM photograph of FIG. 4 , it can be confirmed that the number of beads is very large at -300 nA. When the current value was within ±100 nA, the bead amount was minimized, and when the current value was about +40 nA, the bead almost disappeared. The current value at which the bead amount is minimized or eliminated may vary depending on temperature, humidity, polymer concentration, applied voltage, and the like.

The diameter of the fiber can be adjusted in the range of 10 to 500 nm, preferably 20 to 300 nm, preferably 30 to 200 nm. The diameter of the fiber may vary depending on the polymer concentration and applied voltage, and the like, and the desired diameter of the fiber may be obtained by appropriately setting the polymer concentration and applied voltage.

5 to 7 are SEM photographs of polyacrylonitrile (PAN) and nanofibers according to an applied voltage, as the polymer concentration is lower and the voltage is higher, the fiber diameter is reduced, the higher the polymer concentration and the lower the voltage The fiber diameter increases.

As can be seen from the result photos of FIGS. 5 to 7, and as can be easily seen through the existing literature search, the sections in which the polymer concentration is 7 wt%, 8 wt%, and 9 wt% cannot actually obtain stable fibers, that is, This is the concentration section in which many beads occur. That is, conventionally, fibers were prepared only with a polymer concentration of 10 wt% or more. This is because, as the concentration of the polymer is lower, the force balance between the stretching (stretching) force and the surface tension force by the charged (charged) force of the solution radiated from the nozzle through the applied voltage is broken. However, if the concentration of polymer is increased to obtain stable fibers, thin fibers cannot be obtained.

The present invention technology can solve these existing problems. Specifically, if the apparatus and method of the present invention are applied, even when the concentration of the polymer solution is 10% by weight or less, it is possible to manufacture a fiber having a stable fiber shape with no or minimized beads. That is, according to the present invention, since stable fiber production is possible even at a lower polymer concentration than before, the selection range of the usable polymer concentration is wider than before, and the polymer concentration can be lowered or higher according to the desired fiber diameter.

The filter manufactured according to the present invention has fibers uniformly arranged, does not contain beads between fibers, and has a sufficiently thick thickness, so that it is possible to manufacture and supply a high-quality filter with improved filtration performance compared to conventional filters.

As such, the present invention is provided with an ionizer, a flow disperser, an air compressor, and a flow controller as a device, and methodically, by controlling the amount of ions, applied voltage, and polymer concentration, the fiber shape and fiber diameter can be adjusted as desired. can

By utilizing the present invention, it is not only independent of the concentration of the polymer (ie, the polymer concentration is 10% by weight or less), but also the desired fiber shape and fiber diameter can be obtained. In addition, since the range of the adjustable fiber diameter in the present invention includes a slip effect section in which the efficiency of the nanofiber filter is maximized, it is possible to manufacture a filter having a relatively low-differential pressure and high-efficiency.

The present invention has the advantage of being able to freely adjust the performance of the filter manufactured by the user by adjusting the desired fiber shape, fiber diameter, and fiber spinning time. The present invention can be applied wherever fibers are dealt with. In addition, due to the corona virus, the demand for high-efficiency fibers and filters is also increasing in time, and since the current corona crisis can also change people's thinking and lifestyle, the present invention is also used to manufacture fibers for masks This is possible, and accordingly, the marketability and expected effect are expected to be very large.

10: electrospinning machine, 20: power source, 30: substrate, 40: support, 50: ionizer, 60: multimeter, 70: air compressor, 80: filter, 90: regulator, 100: flow controller, 110: flow disperser, 112: 1st hole, 114: 2nd hole

Claims (11)

An electrospinning machine that forms fibers by spinning a polymer solution, a substrate that collects fibers formed from the electrospinning machine, a support for supporting the substrate, a flow disperser installed inside the support, an ionizer installed on the support to provide ions with polarity opposite to the fiber polarity , using a filter manufacturing device including a multimeter connected to the substrate and measuring the current of the fiber and the ionizer, an air compressor providing compressed air to the support, and a flow controller controlling the flow rate of compressed air,
performing electrospinning by selecting a specific polymer concentration;
adjusting the applied voltage during electrospinning;
A filter manufacturing method comprising the step of adjusting the amount of ions provided to the fibers collected on the substrate. The method of claim 1,
The flow disperser is configured in the form of a plate, and a filter manufacturing method comprising a plurality of first holes disposed in a central region of the plate, and a plurality of second holes disposed in an outer region of the plate and having a larger diameter than the first hole. The method of claim 1,
The polymer concentration is selected within the range of 1 to 20% by weight of the filter manufacturing method. The method of claim 1,
A filter manufacturing method in which the applied voltage is adjusted in the range of 1 to 20 kV. The method of claim 1,
A filter manufacturing method in which the amount of ions is controlled in the range of 1×10 ⁶ to 9.99×10 ⁸ cc. The method of claim 1,
A filter manufacturing method in which the amount of ions is controlled by controlling the flow rate of compressed air. The method of claim 1,
A filter manufacturing method in which the flow rate of compressed air is controlled in the range of 0.01 to 5 m/s. The method of claim 1,
A filter manufacturing method that controls the amount of ions so that the current value measured with a multimeter is within the range of ±100 nA. The method of claim 1,
A filter manufacturing method in which the diameter of the fiber is controlled in the range of 10 to 500 nm. The method of claim 1,
A method for manufacturing a filter capable of manufacturing bead-free fibers even when the concentration of the polymer solution is 10% by weight or less. an electrospinning machine for spinning a polymer solution to form fibers;
a substrate for collecting fibers formed from the electrospinning machine;
a support for supporting the substrate;
flow disperser installed inside the support;
an ionizer installed on the support to provide ions of opposite polarity to the fiber polarity;
a multimeter connected to the substrate to measure the current of the fiber and the ionizer;
an air compressor for providing compressed air to the support;
Filter manufacturing apparatus comprising a flow controller for controlling the flow rate of compressed air.

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