KR101072183B1 - Method for Preparing Nanoweb Filter and Nanoweb Filter Prepared by the same - Google Patents

Abstract

In the present invention, in manufacturing a nano-web filter by the electrospinning method, the filament discharged from the spinning nozzle is passed through a heating unit installed at the bottom of the spinning nozzle to maintain a constant temperature in the spinning zone in a predetermined range, and then to spin It relates to a method for producing a nano-web filter characterized in that the fibers discharged from the zone is integrated on the collector while drawing with air of a predetermined temperature and pressure. According to the manufacturing method of the nano-web filter of the present invention, it is possible to manufacture a high-efficiency and high-function nano web filter at a low cost.

Nano web, filter, electrospinning, heating unit, air guide, substrate, polypropylene

Description

Method for preparing nanoweb filter and nanoweb filter manufactured by the same {Method for Preparing Nanoweb Filter and Nanoweb Filter Prepared by the same}

The present invention relates to a method for manufacturing a nanoweb filter and a nanoweb filter manufactured by the present invention. More particularly, in manufacturing a nanoweb filter by electrospinning, the filament discharged from the spinning nozzle has a constant temperature in a spinning zone. The present invention relates to a method for producing a high-performance / high-efficiency nanoweb filter, and a nanoweb filter produced by the same, characterized in that it is integrated with a collector while being stretched by air of a predetermined temperature and pressure.

With the rapid development of the modern industry, attention has been focused on environmental pollution, and the development of filters to block various harmful substances is also actively progressing. Filters are widely used for purification of industrial products, water treatment facilities for wastewater, and adsorption and removal devices for harmful exhaust gases from incineration plants.

ULPA (Ultra Low Penetration Air) or HEPA (High Efficiency Particulate Air) filters are attracting attention as the next generation materials in the global filter market as high efficiency filters, but are mainly made of glass fibers. These glass fiber materials have to rely on imports, and glass fiber breaks down over time, increasing the defect rate of high-precision products such as semiconductors and displays, and possibly inhaling glass fragments. Causing problems.

Nanofibers are ultra-fine fibers and have a very high surface area to volume ratio and high porosity compared to conventional fibers. Therefore, when implementing nanofiber filters using nanofibers, highly efficient ultra-fine fibers can efficiently remove harmful particles and gases. It is expected to be implemented as a functional filter. However, the implementation of the filter using nanofibers is enormous, and it is difficult to control a variety of conditions for production, so that the filter using nanofibers is not produced and distributed at low cost. Therefore, the development of a method that can produce a filter using a high performance nanofiber at a low cost is required.

The present invention is to overcome the limitations of the prior art as described above, one object of the present invention is to provide a method for producing a nano-web filter that can mass-produce a high-efficiency super functional nanoweb filter using nanofibers at low cost It is.

Another object of the present invention is to provide a highly efficient super-functional nanoweb filter that can effectively block various harmful substances using nanofiber web and has excellent manufacturing processability.

Other objects, advantages and novel features of the invention will become more apparent from the following detailed description and preferred embodiments in conjunction with the accompanying drawings.

One embodiment of the present invention to achieve the above object is

Forming a nanofibrous layer by electrospinning a polymer solution or melt on the surface of a network substrate to form a nanofiber layer, the method comprising: before discharging from a spinning nozzle and integrating on a collector;

In the case of electrospinning the melt through the heating unit installed at the end of the spinning nozzle, while the filament discharged from the spinning nozzle is integrated into the collector, the temperature (T _H ) of the spinning zone is kept constant within the range of the following equation (1) Doing; And

[Equation 1]

T _m -15 ° C ≤ T _H ≤T _m +15 ° C

Wherein T _H is the temperature of the spinning zone,

T _m is the melting temperature of the spinning polymer.

And fabricating the nanoweb filter on the collector while drawing the filaments discharged from the spinning zone using air of a predetermined temperature supplied by an air guide installed at the end of the heating unit. It is about a method.

Another embodiment of the present invention for achieving the above object relates to a high efficiency superfunctional nanoweb filter produced by the method of the present invention.

In the method of the present invention, by using polypropylene, polyamide, polyethylene, cellulose, and polyester substrates instead of glass fibers, the conventional ULPA and Hepa using glass fibers while reducing production costs and overcoming environmental pollution problems. Filters that can deliver superior filtration performance beyond HEPA filters can be mass produced at low cost. In addition, it is possible to provide an ultra-thin film filter having a large collecting capacity because the nanofiber layer can be manufactured from thinner nanofibers by adjusting the conditions of the spinning zone and spinning while stretching by air.

Hereinafter, the present invention will be described in more detail with reference to the accompanying drawings. The same elements in the drawings will be described with the same reference numerals as much as possible even though they are shown on different drawings. In the following description of the present invention, a detailed description of known general functions or configurations will be omitted.

In one aspect the present invention relates to a method of making a nanoweb filter. In the present invention, in the manufacture of a filter by forming a nanofiber layer by spinning a polymer solution or a melt on the surface of the reticulated substrate by electrospinning, it passes through a heating unit installed at the bottom of the spinneret before discharged from the spinneret and accumulated on the collector While the filament discharged from the spinning nozzle is integrated into the collector, the temperature (T _H ) of the spinning zone is kept constant within the range of Equation 1 to fiberize:

[Equation 1]

T _m -15 ° C ≤ T _H ≤T _m +15 ° C

Wherein T _H is the temperature of the spinning zone,

T _m is the melting temperature of the spinning polymer.

The filaments radiating from the spinning zone are then integrated onto the collector while stretching using air at a predetermined temperature supplied by an air guide installed at the end of the heating unit.

 In the present invention, "directly below the radiation nozzle" does not necessarily mean physically downward, but includes all directions toward the collector, such as directly, directly, horizontally or diagonally, of the spinning nozzle.

1 is a schematic cross-sectional view of an electrospinning apparatus that may be used in practicing the method of the present invention. Referring to FIG. 1, the electrospinning device includes a polymer supply unit 100 supplying a polymer melt, a radiation nozzle 310 through which a polymer spinning liquid transferred from the polymer supply unit is discharged, and a high voltage generator applying a high voltage to the spinning nozzle. 400, a collector 500 for collecting fibers discharged from the spinning nozzle, and further, the apparatus is installed directly below the spinning nozzle 310 to maintain a constant temperature in the spinning zone and discharge the fibers. It includes a heating unit 330 for inducing and an air guide 340 attached to the end of the heating unit tubular and guides the fiber exiting the spinning zone while drawing in the direction of the collector by air.

In the present invention, a predetermined substrate 600 is placed on the collector 500, and the nanofibers spun in a nanoweb state on the substrate 600 are collected and composited. In the present invention, the substrate 600 may be used as long as it is a non-woven fabric such as melt blown nonwoven fabric, spunbond nonwoven fabric, needle punching and spunlace nonwoven fabric, and a substrate capable of integrating a nanofiber layer such as woven fabric, knitted fabric, and paper. In view of cost, a polypropylene substrate is preferred.

In the conventional electrospinning, since only an electric field is formed between the spinning nozzle and the collector, nanofibers are radiated to form a nanofiber web, it is difficult to control the thickness and pore size of the manufactured web. However, in the present invention, the guide unit 330 is made of ceramic, tempered glass, electrically insulating inorganic material, etc., which does not conduct current between the radiating nozzle and the collector, and at the end of the heating unit, high temperature is applied to the nanofibers radiated from the radiating nozzle. The air guide 340 for ejecting the air is mounted. Therefore, the nanofibers are formed in the guide unit 330 and the formed nanofibers are drawn by an air flow generated at the end of the heating unit 330 so that the thinner fibers can be collected in the collector without injuring the fibers. . In the present invention, it is possible to control the properties of the nanofibers by adjusting the temperature of the heating unit, the flow rate of air in the air guide, the temperature of the air and the like.

The heating unit 330 is a chamber of a rectangular shape, and is heated in an electrical manner to help maintain the temperature of the spinning zone constant or by heating with hot air to help form the nanofibers. The heating unit 330 may be made of a material such as ceramic, tempered glass, electrically insulating inorganic material as an electrical insulating material.

The air guide 340 is a conical shape in which air of a predetermined temperature is injected to both sides of the spinning nozzle 310, the inner diameter of the pipe for transporting air may be in the range of about 0.5 to about 4 cm. The width of the heating unit 330 is not particularly limited and may be adjusted according to the spinning conditions, but generally 1 to 15 cm, the height of the heating unit is preferably in the range of 5 to 20 cm.

The flow rate of the air injected into the fiber spun from the air guide is 1 ~ 10,000m / min, preferably 1 ~ 3000m / min, the air pressure is 1 ~ 150psi, the temperature of the air is 350 ℃ at room temperature, preferably It is 150 ℃ at room temperature, and the interval between the spinneret 310 lower end and the collector 500 is 1 ~ 25cm, preferably 5 ~ 20cm.

The method of the present invention can be used for both solution electrospinning or melt electrospinning, but can provide significant effects over conventional solution electrospinning when used for melt electrospinning.

In the present invention, when integrating the nanofibers on the collector can be variously carried out in any desired direction depending on the position of the collector, such as top-down, bottom-up, transverse direction, bottom-up is more preferable for mass production. In the case of manufacturing the nanoweb filter from the bottom up, the spinneret outlet is formed in the upper direction, and the collector is located on the top of the spinneret. As shown in FIG. 2, in the case of electrospinning in the lateral direction, a phenomenon in which the drop of the radiation source solution contaminates the substrate can be prevented.

The polymer supply part 100 is a part in which a polymer material, which is a fiber raw material, is supplied and dissolved in a solution or phase-changed into a melt, and a metering pump for quantitatively supplying the polymer storage part 130 and the solution to the spin pack 300. 150).

Spinning liquids include, but are not limited to, polymer solutions, polymer melts, polymers prior to becoming ceramic, and mixtures thereof. Some representative polymers include all polymer materials soluble in solvents such as fluoropolymers, polyolefins, polyimides, polylactides, polyesters, polycaprolactones, polyvinylidene fluorides, polyacrylonitriles, polysulfones, polyimides, polyethylene oxides May be used, or may be used singly or in a mixture of two or more. In the present invention, other additives may be added to the polymer solution or the molten polymer to improve physical properties.

The radiation pack 300 may include a plurality of radiation nozzles 310 (see FIG. 2). The number of spinnerets 310 or the number of spinnerets 300 constituting the spinneret 300 may be set in consideration of the size, thickness, and production speed of the nanofiber web to be manufactured. In consideration of the electric field interference prevention, the contact between the discharge stream, the available space of the radiation nozzle, the spacing between the radiation nozzles installed in the spinning pack 300 is preferably 2 ~ 500mm, more preferably 3 ~ 300mm It is composed.

As described above, in the case of using multiple spinning nozzles connected with a plurality of spinning nozzles, a heating unit and an air guide may be installed for each spinning nozzle to independently perform the fiberization step and the integration step for each spinning nozzle.

In the present invention, the high voltage generator 400 is installed to be immersed in the spinning solution to charge the solution when voltage is applied. Preferably, the voltage applied to the high voltage generator is in the range of 10 ~ 100kV is suitable for nanometer-class radiation.

In the present invention, the temperature of the radiation zone controlled by the heating unit 330 and the temperature of the air in the air guide can be adjusted using a separate temperature controller (not shown). The thermostat may be installed independently of the heating unit and the air guide, or may be configured to control the temperature of the air in the heating unit and the air guide when the heating unit is heated by the hot air heating method. Such a thermostat may include a sensor for sensing the temperature of the air and a control board for controlling the temperature of the air according to the sensed temperature. The temperature sensor may use any sensor used in the technical field to which the present invention belongs, such as a voltage meter, an amphere meter, a thermometer, and the like.

The fibers discharged from the spin pack 300 are collected on the charged collector 500. The collector 500 is grounded, or is applied with a voltage of opposite polarity (or ground) to the polarity of the voltage applied to the spin pack 300 side, for example, the spin pack 300 by a conveyor belt method through a conveying means such as a roller. It is preferable to comprise so that it may supply continuously below.

As a material of the collector 500, a metal plate having excellent conductivity is preferably used. In addition, various kinds of conductive materials may be employed. The distance between the end of the spinning nozzle 310 and the collector 500 is preferably set to 1 to 25 cm with respect to the collector 500 so that an appropriate electric field for stretching the filament is formed.

Referring to the manufacturing process of the nano-web filter by the method of the present invention in more detail as follows. First, when the polymer is quantitatively supplied from the polymer supply part 100 to the spinning pack 300, the polymer spinning solution is charged through the high voltage generator configured in the spinning pack 300. The polymer spinning liquid of the polymer supply part 100 is discharged through the spinning nozzle 310 of the spinneret insulated and to which a high voltage is applied. Air is injected through air guides 340 positioned at both sides of the spinning nozzle 310. Subsequently, the charged solution is discharged to the collector 500 below in the form of fine filaments while passing through the capillary of the spinning nozzle 310.

The filaments exiting the spinning zone where the temperature is kept constant by the heating unit 330 are elongated and radiated to a nano-grade diameter by air of a predetermined temperature and pressure supplied by an air guide attached to the end of the heating unit. do. When stretched and integrated in this manner, a fine web having a fineness of monofilament having a diameter of 1 µm or less, more preferably 20 nm to 800 nm can be obtained.

The collector 500 is configured in the form of a conveyor belt or a rotating drum to be transported to continuously accumulate filaments. Accordingly, a web made of nanofibers is manufactured on the upper surface of the collector 500 or the upper surface of the substrate 600. do. A nanoweb filter can be prepared by separating the integrated nanofibers from the collector in a continuous mat form using a transfer roller, and then winding them up in a winder.

According to the method of the present invention, nanoscale fibers having a diameter of several tens of nm to several hundred nm can be obtained, and nanowebs having a thickness of 0.1 to 3000 µm can be prepared by integrating such nanofibers into a collector.

In the present invention, a functional material such as silver (Ag) and titanium oxide (TiO ₂ ) may be fixed to a surface of the manufactured nanoweb filter to impart additional functionality such as antibacterial properties. For example, the functional nanomaterial may be coated on the surface of the nanofiber layer by magnetron sputtering.

 Another aspect of the invention relates to a nanoweb filter produced by the method of the invention. The nanoweb filter of the present invention, as shown in FIG. 3, includes a filter substrate 50 and a nanofiber layer 70 formed on the substrate. Nanofiber layer 70 is the ultra-fine nanofibers are electrospun and fused into a three-dimensional network at the same time to form a porous web.

The material of the filter substrate 50 is not particularly limited, but polypropylene, polyamide, polyethylene, cellulose, polyester, or a mixture thereof may be used, and it is preferable to use a polypropylene substrate.

The nanofiber layer 70 may be formed of fluoropolymer, polyolefin, polyimide, polylactide, polyester, polycaprolactone, polyvinylidene fluoride, polyacrylonitrile, polysulfone, polyimide, polyethylene oxide and mixtures thereof. It may include.

Optionally, the nanoweb filter of the present invention may further include a functional coating layer coated with a functional material such as silver (Ag) and titanium oxide (TiO ₂ ) on the nanofiber layer 70.

Since the nanoweb filter of the present invention has a large collection capacity and a low pressure loss for the same collection efficiency, it is possible to effectively remove harmful substances such as viruses by removing nano-contaminant particles. Therefore, the nanoweb filter of the present invention can be used for various sanitary or industrial filters, for example, a high performance filter used in semiconductor, food, pharmaceutical, medical, special chemical, air or specific gas applications, space development. Can be used.

 Hereinafter, the present invention will be described in more detail with reference to Examples. These examples are intended to illustrate preferred embodiments of the present invention, and the scope of protection of the present invention is not limited to these examples.

Example  One

Hyosung Polyamide Nylon 6 was added to a formic acid solution and stirred at room temperature for 12 hours to prepare a 15 wt% spinning solution. The prepared solution was electrospun on a meltblown polypropylene substrate having a basis weight of 40 g / m 2 using an electrospinning apparatus, and a voltage of 24.5 kV and a distance between the spinneret and the collector were set to 8 cm. The nozzle used at this time was 21 gauge, and ambient temperature and humidity were 32.6 degreeC and 25%, respectively. Between the nozzle and the collector, air at 100 ° C. was applied at 2 psi pressure. The nanofibers collected on the electrospun nanoweb and the polypropylene substrate are shown in FIG. 4.

Experimental Example  One

The filter efficiency of the polypropylene substrate used as the nanoweb filter and the general filter obtained in Example 1 was evaluated by the following method.

       It generates NaCl aerosol from 0.1㎛ to 0.6㎛ sequentially at a constant flow rate and pressure, passes it through the filter, and measures the rate of particle filtering. At this time, if the 0.3㎛ particles are filtered more than 99.97% it is called hepa filter. The filter efficiency of the nanoweb filter prepared in Example 1 and the polypropylene substrate itself was evaluated and described in Table 1 below.

Filter efficiency (%, 0.3㎛) Nano Web Filter (Example 1) 99.972% Propylene Base (40gm ² ) 68.965%

As can be seen from the results of Table 1, Example 1 of the present invention is to improve the collection efficiency of the filter compared to the conventional general filter to improve the efficiency of the filter, reduce the unit weight and improve the output per unit time Can be.

Although the above has been described in detail with reference to a preferred embodiment of the present invention, this description is merely to describe and disclose an exemplary embodiment of the present invention. Those skilled in the art will readily recognize that various changes, modifications and variations can be made from the above description and the accompanying drawings without departing from the scope and spirit of the invention, and such variations or modifications should be construed as belonging to the claims of the invention. .

1 is a schematic cross-sectional view of an nanoweb electrospinning apparatus of one embodiment used in the present invention.

Figure 2 is a schematic cross-sectional view of another embodiment nanoweb electrospinning apparatus used in the present invention.

3 is a schematic cross-sectional view of a nanoweb filter according to an embodiment of the present invention.

4 is a scanning electron micrograph of a nanoweb filter (left) and a nanoweb cross section (right) produced in Example 1. FIG.

* Description of the symbols for the main parts of the drawings *

100: polymer supply part 300: spin pack

310: spinning nozzle 330: heating unit

340: air guide 400: high voltage generator

500: collector 600: substrate

            50: filter base material 70: nanofiber layer

Claims (8)

In manufacturing a filter by forming a nanofiber layer by spinning a polymer solution or melt on the surface of a network substrate by electrospinning, a filament discharged from the spinning nozzle is installed at the bottom of the spinning nozzle before being discharged from the spinning nozzle and accumulated on the collector. Passing the heating unit to keep the temperature T _H of the spinning zone constant within the range of Equation 1 to fiberize; And [Equation 1] T _m -15 ° C ≤ T _H ≤T _m +15 ° C Wherein T _H is the temperature of the spinning zone, T _m is the melting temperature of the spinning polymer And fabricating the filaments discharged from the spinning zone while integrating the filaments discharged from the spinning zone using air at a predetermined temperature supplied by an air guide installed at the end of the heating unit. . The method of claim 1, wherein the base material is a polypropylene, polyamide, polyethylene, cellulose, polyester fiber layer. The method of claim 1, wherein the flow rate of the air jetted by the air guide is 1 ~ 10,000m / min, the temperature of the air is in the range of 350 ℃ at room temperature. The method of claim 1, wherein the polymer solution or melt is a fluoropolymer, polyolefin, polyamide, polylactide, polyester, polycaprolactone, polyvinylidene fluoride, polyacrylonitrile, polysulfone, polyamide, polyethylene oxide And a polymer selected from the group consisting of mixtures thereof. The method of claim 1, wherein the spinning nozzle is a plurality of spinning nozzles are connected to a plurality of spinning nozzles and a heating unit and an air guide is installed for each spinning nozzle so that the fiberizing step and the integration step is independently for each spinning nozzle Method for producing a nanoweb filter, characterized in that carried out. The method of claim 1, wherein the method performs radiation from the spinneret to the collector in a top-down, lateral or bottom-up manner. The method of claim 1, wherein the method further comprises coating a functional material selected from the group consisting of silver and titanium oxide on the nanofiber layer. A nanoweb filter manufactured by the method of any one of claims 1 to 7.

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