KR102730245B1 - Nano fiber filter and its manufacturing method - Google Patents

Abstract

The present invention relates to a nanofiber filter and a manufacturing method thereof, which ensures antibacterial properties, breathability, and visibility, and can obtain excellent capture efficiency for dust and the like including infectious pathogens, and can be applied to various objects including the human body by being bonded with an eco-friendly water-based adhesive, the steps of: a) introducing a first mesh layer into an electrospinning device; b) forming a nanofiber layer by electrospinning a polyvinylidene fluoride (PVDF) solution on the first mesh layer; c) performing a preliminary coating of an eco-friendly water-based adhesive on the upper surface of the nanofiber layer and the lower surface of the second mesh layer using a roller; d) winding the nanofiber layer and the second mesh layer respectively on a pipe or drum and then leaving them at room temperature for 2 to 6 hours so that the initially coated water-based adhesive permeates into the nanofiber layer and the second mesh layer; e) performing a final coating of an eco-friendly water-based adhesive on the upper surface of the nanofiber layer using a roller; f) a step of thermally pressing and bonding the first mesh layer and the second mesh layer, which are coated with an eco-friendly water-based adhesive, by passing them between upper and lower rollers heated to a temperature of 60 to 90°C; and g) a step of completely drying them at room temperature for 48 to 96 hours.
It includes a nanofiber filter manufactured by the above manufacturing method.

Description

Nano fiber filter and its manufacturing method {Nano fiber filter and its manufacturing method}

The present invention relates to a nanofiber filter and a method for manufacturing the same, and more specifically, to a filter in which a nanofiber layer and a nanofiber layer protective mesh layer are bonded using an eco-friendly water-based adhesive so as to not only have excellent antibacterial properties, breathability, and visibility, but can also be applied to various objects including the human body, and to obtain excellent capture efficiency for various types of dust, including infectious pathogens.

In general, nanofibers are ultra-fine fibers with a diameter of only tens to hundreds of nanometers, and are produced using an electric field. In other words, nanofibers are manufactured and produced by applying a high-voltage electric field to a raw polymer material to generate an electrical repulsive force inside the raw polymer material, which causes the molecules to clump together and split into nano-sized threads. At this time, the stronger the electric field, the more the raw polymer material is torn into thinner pieces, so nanofibers with a thickness of 10 nm to 1,000 nm can be obtained.

Meanwhile, a filter is a filtering device that filters out foreign substances in a fluid and is classified into a liquid filter and an air filter. In particular, an air filter is used to remove fine particles such as dust, biological particles such as bacteria and mold, and biologically harmful substances such as bacteria and viruses in the air.

Conventional air filters made of simple non-woven fabrics have the advantages of a simple manufacturing process and low cost, and are widely used in various fields of application. However, they have the disadvantage of low dust filtration efficiency, and in particular, there is a problem of low capture capacity for fine dust of 25㎛ or less in size, which is harmful to the human body.

In order to improve the fine dust collection efficiency of the above-mentioned non-woven air filter, air filters using non-woven fabrics with added electrostatic charge have been developed and used, but there is a problem that the electrostatic characteristics of the electrostatic filter decrease due to rain or moisture contact or penetration, and the dust collection efficiency rapidly decreases. For example, there were various problems such as the decrease in dust collection efficiency due to the decrease in electrostatic characteristics decreasing from the initial dust collection efficiency of 99.97% to about 30%.

Korean Patent Publication No. 10-1585506 (Title of the invention: Patterned flexible piezoelectric element based on PVDF nanofibers using electrospinning and its manufacturing method, patent announcement on January 15, 2016) Korean Patent Publication No. 10-1079775 (Title of the invention: Method for manufacturing electrically conductive nanofibers through electroless plating followed by electrospinning, Patent announcement on November 3, 2011)

The purpose of the present invention is to provide a nanofiber filter and a method for manufacturing the same, which not only has excellent antibacterial properties, breathability, and visibility, but can also be applied to various objects including the human body, and can obtain excellent capture efficiency for various types of dust, including infectious pathogens, by bonding a nanofiber layer and a nanofiber layer protective mesh layer with an eco-friendly water-based adhesive.

A method for manufacturing a nanofiber filter according to one embodiment of the present invention comprises the steps of: a) introducing a first mesh layer into an electrospinning device; b) electrospinning a polyvinylidene fluoride (PVDF) solution onto the first mesh layer to form a nanofiber layer; c) performing a preliminary coating of an eco-friendly water-based adhesive on the upper surface of the nanofiber layer and the lower surface of the second mesh layer using a roller; d) winding the nanofiber layer and the second mesh layer respectively onto a pipe or drum and then leaving them at room temperature for 2 to 6 hours so that the initially coated water-based adhesive permeates into the nanofiber layer and the second mesh layer; e) performing a final coating of an eco-friendly water-based adhesive on the upper surface of the nanofiber layer using a roller; f) passing the first mesh layer and the nanofiber layer and the second mesh layer, which have been finished with the eco-friendly water-based adhesive, between upper and lower rollers heated to a temperature of 60 to 90°C to perform thermal compression and bonding; and g) performing a complete drying step at room temperature for 48 to 96 hours.

Another embodiment of the present invention provides a method for manufacturing a nanofiber filter, comprising the steps of: a`) first coating an eco-friendly water-based adhesive on the upper surface of a first mesh layer using a roller; b`) naturally drying the first mesh layer, which has been first coated, at room temperature so that the moisture content of the first mesh layer is maintained at 40 to 60%; c`) introducing the first mesh layer into an electrospinning device; d`) forming a nanofiber layer by electrospinning a polyvinylidene fluoride (PVDF) solution on the first mesh layer; e`) re-coating an eco-friendly water-based adhesive on the upper surface of the nanofiber layer and the lower surface of the second mesh layer using a roller; f`) winding the nanofiber layer and the second mesh layer respectively onto a pipe or drum and then leaving them at room temperature for 2 to 6 hours so that the re-coated water-based adhesive permeates into the nanofiber layer and the second mesh layer; g`) finishing coating the upper surface of the nanofiber layer with an eco-friendly water-based adhesive using a roller; h`) a step of thermally compressing and bonding the nanofiber layer and the second mesh layer by passing them between upper and lower rollers heated to a temperature of 60 to 90°C; i`) a step of completely drying them at room temperature for 48 to 96 hours to obtain a nanofiber filter.

Instead of the step of obtaining a nanofiber filter by completely drying at room temperature for 48 to 96 hours, the method includes a step of obtaining a nanofiber filter by drying at a temperature of 60 to 90°C for 12 to 24 hours and then completely drying at room temperature for 12 to 24 hours.

The above eco-friendly water-based adhesive contains 5 to 15 wt% of water, 10 to 22 wt% of water-based EVA copolymer, 65 to 75 wt% of water-based acrylic copolymer, and 2 to 5 wt% of VOC reduction agent.

The amount of the above-mentioned water-based adhesive coating (application) can be 8 to 30 g/㎡.

The glass transition temperature (Tg value) of the above-mentioned water-based adhesive can be -25 to 0°C.

The above water-based adhesive may further include 1 to 10 wt% of adipic dihydrazide mixed therein.

The water-repellent agent further comprises 2 to 8 wt% of a water-repellent agent mixed into the above-mentioned water-repellent agent, and the water-repellent agent may be an environmentally friendly fluorine-based water-repellent agent of C6 or lower or a silicone-based water-repellent agent.

The glass transition temperature of the above-mentioned water-based adhesive can be -25 to 0°C, and the viscosity can be 300 to 800 cps.

It includes a nanofiber filter manufactured by at least one of the above nanofiber filter manufacturing methods.

A nanofiber filter manufactured by at least one of the above methods for manufacturing a nanofiber filter, wherein the nanofiber layer is transparent white and may have a transparency of 70 to 90%.

A nanofiber filter manufactured by at least one of the above nanofiber filter manufacturing methods may be any one of a mask, a hat, gloves, a dust-proof suit, a protective suit, a dust-proof net, an air purifier, an air filter for ventilation, an air filter for transportation, and an industrial filter.

The above nanofiber filter includes a first mesh layer composed of a fiber mesh having a predetermined mesh size, a nanofiber layer electrospun and bonded to an upper surface of the first mesh layer using a polyvinylidene fluoride (PVDF) solution, and a second mesh layer adhered to the upper surface of the nanofiber layer and composed of a fiber mesh having a predetermined mesh size.

The above nanofiber layer can have a basis weight of 0.05 to 0.5 gsm and an air permeability of 80 to 150 cfm.

The above first mesh layer may have a mesh size of 6,400 to 10,000 and a weight of 15 to 30 gsm.

The above second mesh layer may have a mesh size of 1,225 to 3,025 and a weight of 40 to 55 gsm.

The color of the above nanofiber layer is transparent white, and the transparency can be 70 to 90%.

The amount of water-based adhesive applied to the first and second mesh layers and the nanofiber layer may be 8 to 30 g/㎡.

The present invention has high transparency and thus excellent visibility, and has excellent effects as a filter by filtering out fine dust viruses, etc., and since volatile organic compounds (VOCs), formaldehyde, acetaldehyde, etc. are not detected, it has the effect of being widely applicable not only to objects or articles applied to the human body (face masks, clothing), but also to various objects.

The present invention has the advantage of effectively blocking not only dust, particulate matter, yellow dust, pollen, particulate matter, mist, dust, etc., but also various pathogens, germs, bacteria, viruses, and other infectious agents and/or droplets containing them, since nano-sized porous pores, which are smaller than fine particles and larger than air, are formed in the nanofiber layer (2).

The present invention is very comfortable to breathe in as the 'differential pressure', which is the pressure difference before and after passing through the nanofiber layer (2), is measured to be 1.4.

The present invention has excellent visibility and transmittance, with about 70 to 80% transmittance, so that the object to which it is applied can be easily identified. For example, in the case of a face mask worn on the face, the entire face including the wearer's face can be identified, and facial makeup or aesthetics or aesthetic feelings expressed on the wearer's face (face) are naturally and completely expressed to the outside, and there is an effect of being able to freely show off aesthetic feelings to people around them.

In addition, since general MB filters (or HEPA filters) absorb and capture fine dust using electrostatic methods, they are weak to moisture or humidity, and have problems such as performance deterioration and shrinkage when worn for a long time, but the nano-fiber filter of the present invention blocks dust, viruses, etc. by a physical method in which dense nano-unit fiber strands are entangled to filter them, so it is hardly affected by moisture or humidity, and in safety tests, various harmful substances were not detected or were below the standard, so it is effective and can be used with confidence.

The present invention has the effect of allowing repeated use because even if various types of dust, fine dust, various foreign substances, germs, bacteria, viruses, etc. are adsorbed or stuck to the nanofiber layer (2), they can be easily separated (detached) by rinsing with water, preferably running water.

The present invention has the effect of being useful as human clothing such as masks, hats, gloves, dust-proof suits, and protective clothing, since a multilayer nanofiber filter is well bonded by a water-based adhesive that is harmless to the human body.

The present invention not only has excellent water-repellent properties without a separate water-repellent treatment, but also has the effect of doubling the water-repellent properties by additionally applying a water-repellent solution.

The present invention is not only harmless to the human body as no harmful heavy metals, other harmful substances, formaldehyde, etc. are detected, but also has the effect of blocking and quickly killing germs, fungi, bacteria, viruses, etc.

The present invention is a very useful invention that, when applied to a face mask or the like due to its high transparency, not only allows the face to be seen, but also prevents (prevents) the transmission of viruses, bacteria, germs, and pathogens through saliva or droplets.

Figure 1: An example of the configuration of a nanofiber filter of the present invention.
Figure 2: Flow chart of a method for manufacturing a nanofiber filter according to one embodiment of the present invention.
Figure 3: Flow chart of a method for manufacturing a nanofiber filter according to another embodiment of the present invention.
Figure 4: Scanning electron microscope image (228x magnification) of a state in which a nanofiber layer is formed on the first mesh layer in the present invention.
Figure 5: Scanning electron microscope image (5,000x magnification) showing the nanofiber layer of the present invention.
Figure 6: Scanning electron microscope image (10,000x magnification) showing the nanofiber layer of the present invention.
Figure 7: Blank photo of strain 1 in the antibacterial activity test of the present invention.
Figure 8: Photograph of the test result of strain 1 in the antibacterial activity test of the present invention (after 18 hours).
Figure 9: Blank photo of strain 2 in the antibacterial activity test of the present invention.
Figure 10: Photograph of the test results of strain 2 in the antibacterial activity test of the present invention (after 18 hours).
Figure 11: A photograph showing the transmittance of the nanofiber filter of the present invention outdoors under sunlight.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the attached drawings. In describing the embodiments of the present invention, identical components in the drawings are described with the same reference numerals as much as possible, and specific descriptions of related known structures or functions are omitted so as not to obscure the gist of the present invention. In addition, matters expressed in the attached drawings are schematic drawings for easily explaining embodiments of the present invention, and may differ from the form actually implemented.

FIG. 1 is a diagram illustrating a layer structure of a nanofiber filter of the present invention, which comprises a first mesh layer (1) composed of a fiber mesh having a predetermined mesh size, a nanofiber layer (2) electrospun and bonded to the upper surface of the first mesh layer (2) using a polyvinylidene fluoride (PVDF) solution, and a second mesh layer (3) bonded to the upper surface of the nanofiber layer (2) and composed of a fiber mesh having a predetermined mesh size.

The present invention effectively blocks not only dust, particulate matter, yellow dust, pollen, particulate matter, mist, dust, etc., but also various pathogens, germs, bacteria, viruses, and other infectious agents and/or droplets containing them, by forming nano-sized porous pores in the nanofiber layer (2) that are smaller than fine particles and larger than air.

The above first and second mesh layers (1)(3) may be a woven net or fiber mesh having a predetermined mesh. The above first and second mesh layers (1)(3) are preferably woven with weft and warp yarns, but may also be a knitted fabric.

The above first and second mesh layers (1) and (3) are adhered or fixed to the upper and lower surfaces of the nanofiber layer (2) to sufficiently protect the nanofiber layer (2) and maintain breathability, visibility, durability, etc.

In the above, the first mesh layer (1) inserted into the electrospinning device (not shown) is formed with a mesh that is denser than that of the first mesh layer (3) so that the contact area can be expanded and the nanofiber layer (2) can be uniformly fixed while being efficiently formed through electrospinning.

For example, the first mesh layer (1) may be 6,400 to 10,000 mesh and have a basis weight of 15 to 30 gsm, and the second mesh layer (3) may be 1,225 to 3,025 mesh and have a basis weight of 40 to 55 gsm.

The weft and warp yarns constituting the first and second mesh layers (1)(3) are extruded at a mixing ratio of 8 to 20 wt%: 92 to 80 wt%, and one or more solvents selected from the group consisting of olefin polypropylene (PP), polyvinylacrylate (PVA), polyacrylonitrile (PAN), polylactic acid (PLA), polyelactide (PLLA), polyethersulfone (PES), polyamide (PA), and gelatin.

The amount of water-based adhesive applied (coating amount) to the first and second mesh layers (1)(3) and the nanofiber layer (2) is 8 to 30 g/m2. If the amount of the water-based adhesive applied is less than 8 g/m2, the desired adhesive strength cannot be obtained, and if the amount of the applied adhesive exceeds 30 g/m2, not only is it wasteful, but the nanofiber layer (2) and nanocell may become brittle, damaged and/or destroyed due to the excessive amount, which is not preferable.

The above first mesh layer (1), nanofiber layer (2), and second mesh layer (3) are bonded using an environmentally friendly water-based adhesive that is harmless to the human body. The above water-based adhesive is harmless and safe to the human body by using an environmentally friendly material that does not have an odor and does not contain any harmful substances.

FIG. 2 illustrates a method for manufacturing a nanofiber filter according to one embodiment of the present invention. The first mesh layer (1) is placed into an electrospinning device (step S1), and then a polyvinylidene fluoride (PVDF) solution is electrospun on the first mesh layer (1) to form a nanofiber layer (2) (step S2), an eco-friendly water-based adhesive is first rolled coated on the upper surface of the nanofiber layer (2) and the lower surface of the second mesh layer (3) using a roller (step S3), and the nanofiber layer (2) and the second mesh layer (3) to which the eco-friendly water-based adhesive is applied are each wound on a pipe or drum, and then left at room temperature for 2 to 6 hours to allow the first roll coated water-based adhesive to sufficiently permeate into the nanofiber layer (2) and the second mesh layer (3) (step S4), and an eco-friendly water-based adhesive is finished rolled coated on the upper surface of the nanofiber layer (2) using a roller (step S5), and the first The mesh layer (1) and the nanofiber layer (2) and the second mesh layer (3) with the eco-friendly water-based adhesive finish coating are passed between upper and lower rollers heated to a temperature of 60 to 90°C to be thermally pressed and bonded (step S6), and then completely dried at room temperature for 48 to 96 hours to obtain a nanofiber filter (step S7).

Instead of completely drying at room temperature for 48 to 96 hours (step S7), a nanofiber filter can be obtained by heating and drying in a drying room at 60 to 90°C for 12 to 24 hours and then completely drying at room temperature for 12 to 24 hours (step S8).

FIG. 3 illustrates a method for manufacturing a nanofiber filter according to another embodiment of the present invention, in which an eco-friendly water-based adhesive is first rolled onto the upper surface of a first mesh layer (1) (step S11), the first mesh layer (1) on which the eco-friendly water-based adhesive is first rolled is naturally dried at room temperature so that the moisture content of the first mesh layer (1) is maintained at 40 to 60% (step S12), the first mesh layer (1) is placed into an electrospinning device (step S13), a polyvinylidene fluoride (PVDF) solution is electrospun onto the first mesh layer (1) to form a nanofiber layer (2) (step S14), an eco-friendly water-based adhesive is second rolled onto the upper surface of the nanofiber layer (2) and the lower surface of the second mesh layer (3) using a roller (secondary roll coating) (step S15), and the nanofiber layer (2) and the second mesh layer (3) on which the eco-friendly water-based adhesive is applied are each wound onto a pipe or drum, and then dried for 2 to 6 hours. By leaving it at room temperature, the coated water-based adhesive is sufficiently permeated into the nanofiber layer (2) and the second mesh layer (3) (step S16), an eco-friendly water-based adhesive is applied as a finish roll coating to the upper surface of the nanofiber layer (2) using a roller (step S17), the first mesh layer (1) and the nanofiber layer (2) and the second mesh layer (3) coated with the eco-friendly water-based adhesive are passed between upper and lower rollers heated to 60 to 90°C to perform thermal compression and bonding (step S18), and the nanofiber filter is obtained by completely drying it at room temperature for 48 to 96 hours (step S19).

Instead of completely drying at room temperature for 48 to 96 hours (step S19), a nanofiber filter can be obtained by heating and drying in a drying room at 60 to 90°C for 12 to 24 hours and then completely drying at room temperature for 12 to 24 hours (step S20).

The above eco-friendly water-based adhesive is an eco-friendly hybrid adhesive containing a water-based EVA (ethylene vinyl acetate) copolymer and a water-based acrylic copolymer. After drying (or curing), it becomes transparent and leaves no trace.

The above eco-friendly water-based adhesive contains 5 to 15 wt% of water, 10 to 22 wt% of water-based EVA (ethylene vinyl acetate) copolymer, 65 to 75 wt% of water-based acrylic copolymer, and 2 to 5 wt% of VOC reduction agent.

The glass transition temperature of the above eco-friendly water-based adhesive is -25 to 0°C, and the viscosity is 300 to 800 cps.

If the glass transition temperature is lower than -25℃, there is a problem that the shape of the nanofiber filter may be easily deformed as the bendability (ductility) of the nanofiber filter becomes too soft, and if the glass transition temperature exceeds 0℃, the nanofiber filter may become hard and cause discomfort when worn, so it is desirable to have a glass transition temperature of -25℃ to 0℃ that is soft and has excellent adhesion.

The above EVA copolymer (ethylene-vinyl acetate copolymer) is a polymer obtained by copolymerizing ethylene and vinyl acetate monomer, and is also called ethylene-vinyl acetate copolymer. As the content of vinyl acetate increases, the density increases, but the degree of crystallization decreases, so the flexibility increases. Low-content EVA is processed like ordinary low-density polyethylene and has excellent impact resistance (especially at low temperatures) and stress cracking resistance, so it is used as an adhesive for heavy packaging materials and laminate films. 10-20% EVA is used for soft vinyl chloride-like purposes, such as foam molded products such as sandals and shoe soles, agricultural films, and industrial stretch films. High-concentration EVA is used as a raw material for adhesives.

The above acrylic copolymer (acrylic resin) refers to a polymer from esters such as acrylic acid and methacrylic acid. A representative example is a polymer of methacrylic acid methyl ester (methacrylic acid methyl), which is colorless and transparent and transmits light, especially ultraviolet rays, better than ordinary glass (refractive index 1.49). It does not discolor even when exposed to the outdoors, has good chemical resistance, and has good electrical insulation and water resistance.

The above VOC reduction agent may be an aqueous solution containing 69 to 90 wt% of water, 4 to 12 wt% of thiourea, 1 to 4 wt% of urea, and 1 to 4 wt% of boric acid, and the VOC reduction agent has the effect of adsorbing and deodorizing components such as volatile organic compounds (VOCs) and formaldehyde, making it harmless to the human body.

The above thiourea (CH ₄ N ₂ S) is an organic compound composed of carbon, nitrogen, sulfur, hydrogen, etc. It is a colorless crystal and has a structure in which the oxygen atoms of the urea are replaced with sulfur atoms, so it is also called thiourea and thiocarbamide. The molecular weight of thiourea is 7312, the melting point is 180℃, and the specific gravity is 1405. It is soluble in water and ethanol, but almost insoluble in ether. The aqueous solution is neutral and has a bitter taste. When hydrolyzed with acid or alkali, it decomposes into ammonia, hydrogen sulfide, and carbon dioxide, and when oxidized with potassium permanganate, it becomes urea, and it has an excellent deodorizing effect.

The above element (urea, 尿素) is an organic compound with the chemical formula CO( _NH2 ) ₂ , a colorless crystalline substance, and the final breakdown product of protein metabolism in all mammals and some fish. It is also called urea, carbamide, and diaminomethanal. It is a colorless, odorless substance that forms columnar crystals, with a molecular weight of 60047, a melting point of 1327℃ (1atm), and a specific gravity of 1335. It is a highly polar substance, so it dissolves well in water and alcohol, but insoluble in ether.

The above boric acid ( _H3BO3 ) is an oxygen acid produced by the hydration of boron oxide, including orthoboric acid, metaboric acid, and tetraboric acid, and is often referred to as orthoboric acid. Orthoboric acid is a raw material for borosilicate _glass and porcelain glaze, and also promotes the dissolution of injections. Orthoboric acid is a colorless, transparent or white, glossy, flaky crystal that is odorless and has a slight, characteristic taste. The melting point is 184–186°C, and the specific gravity is 149.

The nanofiber filter of the present invention removes volatile organic compounds (VOCs), formaldehyde, acetaldehyde, and unpleasant odors, can be used safely in any climate conditions, prevents the growth of various molds and bacteria, and kills germs, pathogens, bacteria, and viruses in a short period of time.

The present invention may further include 1 to 10 wt% of adipic dihydrazide (ADH) mixed in a water-based adhesive. The molecular structure of the adipic dihydrazide is as follows, and the molecule is formed of a total of 26 atoms consisting of 14 hydrogen atoms, 6 carbon atoms, 4 nitrogen atoms, and 2 oxygen atoms. The adipic dihydrazide molecule has a total of 25 chemical bonds, which are composed of 11 non-hydrogen bonds, 2 multiple bonds, 5 single bonds, 2 double bonds, and 2 N hydrazines. Although it has a white powder appearance, when mixed and liquefied in a water-based adhesive, it greatly contributes to reducing formaldehyde in a nanofiber filter coated with the water-based adhesive.

The present invention may further include 2 to 8 wt% of a water-repellent agent mixed into the water-based adhesive. The water-repellent agent is an environmentally friendly fluorine-based water-repellent agent of C6 or less or a silicone-based water-repellent agent.

The polyvinylidene fluoride (PVDF) of the present invention has its own water-repellent function, but by further including the water-repellent liquid, the water-repellent power of the nanofiber filter is doubled.

The above polyvinylidene fluoride (PVDF) is a ferroelectric material and has its own electrostatic charge.

Figure 4 is an image taken at a magnification of 228 times using a scanning electron microscope to show the state in which a nanofiber layer (2) is formed on the weft and warp of the first mesh layer (1), Figure 5 is an image taken at a magnification of 5,000 times the nanofiber layer (2), and Figure 6 is an image taken at a magnification of 10,000 times the nanofiber layer (2).

In Fig. 6, it can be seen that nanofibers with diameters of 125.5 nm, 150.6 nm, 200.8 nm, and 251.0 nm and surrounding nanofibers are configured in a web shape, and the size of the pores (nanocytes) formed between the nanofibers is at least in the range of 50 nm to 1 μm, and ventilation and respiration are achieved by allowing air to enter and exit through the pores.

The above nanofiber layer (2) has a basis weight of 0.05 to 0.5 gsm and also has a breathability of 80 to 150 cfm, so breathing is not burdensome or difficult.

The diameter of the nanofibers of the above nanofiber layer (2) may be 100 nm to 300 nm. If the diameter of the nanofibers is greater than 300 nm, the micronization is not sufficient, the fiber surface area is reduced, and the collection efficiency as a filter medium is reduced, making it difficult to remove fine dust, etc., and on the other hand, if it is smaller than 100 nm, there are problems such as reduced processability, increased density, increased differential pressure, reduced strength, and difficulty in production.

The present invention enables repeated use by easily separating (detaching) various types of dust, fine dust, various foreign substances, germs, bacteria, viruses, etc. that are adsorbed or stuck to the nanofiber layer (2) by rinsing them in water, preferably running water.

The color of the above polyvinylidene fluoride (PVDF) is transparent white (white) or highly transparent white (white), so that the transparency, i.e. visibility, is high, allowing objects located at the rear to be identified.

The first mesh layer (1) and the second mesh layer (3) of the nanofiber filter of the present invention are translucent or opaque, but the color of polyvinylidene fluoride (PVDF), which is a constituent material of the nanofiber layer (2), is transparent or has high transparency and is white (white), and has high visibility, so that objects located at the rear can be identified.

The nanofiber filter of the present invention has a transparency of about 70 to 90%, and as shown in FIG. 11, it has excellent visibility, allowing various objects, shapes, colors, etc. located at the rear to be transmitted by 70 to 90%, thereby differentiating it from existing opaque face masks, etc., and when a face mask is worn on the face, the wearer's face can be seen through it as well, and the entire face including the wearer's face can be seen, so that facial makeup or the aesthetics or aesthetic feelings expressed on the face are directly expressed to the outside.

Also, when applied to a face mask and worn, it can be used not primarily for the purpose of crime or covering the face, but rather as various filters, masks, and coverings that remove biologically contagious (such as MERS/SARS/coronavirus disease-19 (COVID-19)) or harmful substances, such as fine particles such as atmospheric dust, fine dust, yellow dust, pollen, dust, biological particles such as bacteria and mold, bacteria, viruses, and droplets, while naturally revealing the face.

The transparency of the above nanofiber filter can be changed depending on the size and number of nano pores formed in the mesh of the first mesh layer (1) and the second mesh layer (3) and the nanofiber layer (2).

In addition, the colors of the first mesh layer (1) and the second mesh layer (3) can be implemented in various colors by selecting various coloring agents (pigments, etc.). Fig. 1 is an example implemented in white (white), and when configured in black, visibility is further improved by the color contrast with the image transmitted through the nanofiber layer (2).

The above polyvinylidene fluoride (PVDF) polymer is a polymer having a repeating unit of (-CF2-CH2-)n and can have various crystal forms. Basically, there exist an α crystal in the form of TGTG' (T=trans, G=gauche+, G'=gauche-), a β crystal having an arrangement of (TTTT) which is all trans, and a γ crystal having an arrangement of the form TTTGTTTG'.

The principle of electrospinning is that when an electric field is applied to a polymer solution, an electric force is applied to the particles, and positive charges are oriented on the surface of the solution, and the particles are guided to the interface between the air layer and the surface of the solution, and a force opposite to the surface tension is generated by these charges. At this time, the solution overcomes the surface tension when it exceeds the critical voltage, and the sprayed solution is collected by the collector due to the potential difference with the metal collector on the opposite side. Nanofibers can be manufactured using this principle using a polymer solution.

When manufacturing a PVDF nanofiber web by the above-described electrospinning method, the dipole arrangement (C-F) inside the PVDF fiber occurs simultaneously due to the electric field generated when the polymer solution (+) sprayed during the electrospinning process solidifies and is collected on the electrode (integrator) (-pole), so a separate polarization treatment process is not required, and PVDF with a high β crystal content inside the fiber can be manufactured.

Meanwhile, general MB filters (or HEPA filters) absorb and capture dust using electrostatic methods, so they are weak to moisture or humidity, and have the disadvantage of deteriorating performance and shrinking when worn for a long time. However, the nano-fiber filter of the present invention blocks ultrafine dust and viruses by a physical method in which dense nano-unit fiber strands are entangled to filter them, so it is hardly affected by moisture or humidity, and in safety tests, various harmful substances were not detected or were below the standard, so it is effective and can be used with confidence.

In addition, when forming the nanofiber layer (2), the electrospun polyvinylidene fluoride (PVDF) is a ferroelectric material and has its own electrostatic charge, so fine dust and the like are captured more effectively.

Table 1 below shows the results of a test on the detection amount of PBBs (Polybrominated biphenyls) for the nanofiber filter of the present invention. It can be seen that various harmful components were detected below the detection limit, indicating that it is safe for use on the human body.

Test items Results (Unit: mg/kg) Test method Detection limit Monobromobiphenyl less than 5



IEC 62321-6:2015 5 Dibromobiphenyl less than 5 5 Tribromobiphenyl less than 5 5 Tetrabromobiphenyl less than 5 5 Pentabromobiphenyl less than 5 5 Hexabromobiphenyl less than 5 5 Heptabromobiphenyl less than 5 5 Octabromobiphenyl less than 5 5 Nonabromobiphenyl less than 5 5 Decabromobiphenyl less than 5 5

Table 2 below shows the results of tests for PBDEs (Polybrominated diphenyl ethers), showing that various hazardous substances were detected below the detection limit (less than 5 mg/kg) or were not detected, indicating that the product is safe for use on the human body.

Test items Results (Unit: mg/kg) Test method Detection limit Monobromobiphenyl less than 5



IEC 62321-6:2015 5 Dibromobiphenyl less than 5 5 Tribromobiphenyl less than 5 5 Tetrabromobiphenyl less than 5 5 Pentabromobiphenyl less than 5 5 Hexabromobiphenyl less than 5 5 Heptabromobiphenyl less than 5 5 Octabromobiphenyl less than 5 5 Nonabromobiphenyl less than 5 5 Decabromobiphenyl less than 5 5

Table 3 below shows the results of the phthalate detection test, showing that various harmful components were detected at less than the detection limit of 0.01%, indicating that it is safe for use on the human body.

Test items Results (unit:%) Test method Detection limit DEHP less than 0.01
IEC 62321-6:2015 0.01 BBP less than 0.01 0.01 DBP less than 0.01 0.01

* DEHP: DI(2-ETHYLHEXYL)-PHTHALATE * BBP: BENZYLBUTYLPHTHALATE

* DBP : DIBUTYLPHTHALATE

Table 4 below shows the results of the formaldehyde detection test. Since no formaldehyde was detected, it can be seen that it is safe for use on the human body.

Test items Results (Unit: mg/kg) Test method Detection limit Formaldehyde Not detected KS K ISO 14184-1:1998 20(mg/kg)

According to Table 4 above, in the nanofiber filter manufactured according to the embodiment of the present invention, all of the heavy metals, volatile organic compounds (VOCs), volatile aromatic hydrocarbons (VACs), total volatile organic compounds (TVOC), toluene, and formaldehyde were detected in trace amounts at levels that satisfied the certification standards. In addition, formaldehyde was not detected in the test standards expected when the nanofiber filter of the present invention is applied to various filters and masks, thereby satisfying the certification standards. Table 5 below shows the results of quantitative tests for other hazardous substances, which show that they are below the quantitative limit or not detected, indicating that they are safe for use on the human body.

Test items result
(Unit: mg/kg) Test method quantitative limit
(Unit: mg/kg) Methylisothiazolinone
(MIT) Not detected Regulations on standards and methods for testing and inspection of household chemical products subject to safety confirmation [National Institute of Environmental Research Notice No. 2019-70 (December 31, 2019)] 1 Benzisothiazolinone
(BENZISOTHIAZOLIONE) Not detected 1 2-Octyl-3(2H)isothiazolone
(OIT) Not detected 1 5-chloromethylisothiazolinone
(5-CHLOROMETHYLISOTHIAZOLINONE) Not detected 1

Table 6 below shows the results of the UV blocking rate test, showing that the UV blocking rate is excellent.

Test items Results (unit: nm) Measuring instrument Wavelength interval Ultraviolet (UV-R) blocking rate 70.3/44.5/55.6/59.4 UV-VIS-NIR Spectrophotometer
(Perkin Elmer_Lamb 1050 with 150 mm InGaAs int. Sphere) 5nm UV-A blocking rate 63.4/37.6/47.8/51.7 5nm UV-B blocking rate 93.3/66.9/80.9/84.9 5nm

* Wavelength range UV-R: 290~400nm, UV-A: 315~400nm, UV-B: 290~315nm * Individual values are indicated due to variation in data by area.

Table 7 below shows the results of a permeability test of the nanofiber filter of the present invention. Using filter test equipment (filter tester (Lorenz FMP03)) and aerosol-type paraffin oil, the test was performed three times for 30 seconds. As a result, the permeability of the nanofiber filter was 2.9% and the filter efficiency was 97.1%, which are very excellent results.

Transmittance 2.9% Efficiency 97.1%

* Test equipment: filter tester (Lorenz FMP03) * Aerosol type: paraffin oil

*Average aerosol particle size: 0.44㎛

* Aerosol concentration: (20±5) mg/㎥

* Flow rate: 95 L/min

* Number of measurements: 3 times

* Measurement time: 30 seconds

* Efficiency: 100 - Transmittance (%)

In addition, the 'differential pressure', which is the pressure difference before and after passing through the nanofiber layer (2), is measured as 1.4, which shows that it is very comfortable to breathe. For example, among the masks approved by the Ministry of Food and Drug Safety, the differential pressure of the KF-94 product is about 7 to 8, and the differential pressure of the KF-80 is 6 to 7, making it difficult to breathe, whereas the nanofiber filter of the present invention is about 1.4, making it comfortable to breathe.

Table 8 below shows the test results for the bursting strength of the second mesh layer (3) of the nanofiber filter of the present invention, and very excellent results were obtained.

Test items result Test criteria Bursting strength 419.N KS K 0350:2017, (C.R.E) Ball busting method

Table 9 below shows the test results for the tensile strength of the second mesh layer (3) of the nanofiber filter of the present invention for the warp and weft yarns, and very excellent results were obtained.

Test items result Test criteria Tensile strength of slope 270N KS K 0520: 2015, C.R.E, Grave method) Tensile strength of the weft 280N

Table 10 below is the result table of the antimicrobial test (KS K0693: 2016) of the present invention. The sample used in the antimicrobial test is the nanofiber layer (2) of the nanofiber filter, and the antimicrobial test was performed by adding 0.05% of a nonionic surfactant to the bacterial solutions of test strains 1 and 2.

division Number of bacteria immediately after inoculation Count after 18 hours Bacterial reduction rate Strain 1 Sample (BLANK) 1.8 ×10 ⁴ /㎖ 8.7 ×10 ⁶ /㎖ - Nanofiber filter of the present invention - <10/㎖ 99.9% Strain 2 Sample (BLANK) 1.8 ×10 ⁴ /㎖ 3.0 ×10 ⁷ /㎖ - Nanofiber filter of the present invention - 1.2 ×10 ⁴ /㎖ 99.9%

In the above Table 10, 'strain 1' is Staphylococcus aureus ATCC 6538, 'strain 2' is Klebsiella pneumonian ATCC 4352, the standard cloth is 'nanofiber layer (2)', the nonionic surfactant is TWEEN 80 added at 0.05% to the inoculated bacteria solution, and '<' indicates a value less than . FIGS. 7 and 8 are photographs of the antibacterial test for strain 1 (Staphylococcus aureus ATCC 6538). FIG. 7 is a photograph of the bacteria solution (1.8×10 ⁴ ) of the sample (Blank), and FIG. 8 is a photograph of the test result after 18 hours. It can be seen that the antibacterial activity is very excellent as the number of bacteria in 'strain 1' is less than 10 and 99.9% is removed.

Figures 9 and 10 are photographs of an antibacterial test for strain 2 (Klebsiella pneumonian ATCC 4352). Figure 9 is a photograph of a bacterial solution (1.8×10 ⁴ ) of a sample (Blank), and Figure 10 is a photograph of the test result after 18 hours. It can be seen that the number of bacteria of 'strain 2' was 1.2×10 ^{4 ,} which was 99.9% removed, indicating that the antibacterial activity of the nanofiber filter of the present invention is very excellent.

As can be seen from the antibacterial test results above, in the case of the 'nano fiber layer (2)' sample, the initial number of bacteria of strains 1 and 2 was 1.8×10 ⁴ , but after 18 hours, almost all of them were removed, indicating excellent antibacterial activity. Therefore, it is effective in improving the health of users and, furthermore, the health and hygiene of the people.

The present invention has better visibility, air permeability, water repellency and antibacterial properties than microfiber filters of the same performance, and can be easily washed by rinsing in water, allowing repeated use.

The present invention is harmless to the human body and is environmentally friendly, and various bacteria, pathogens, microorganisms, viruses, etc. are killed in a short period of time due to its antibacterial effect, so that various objects can be safely used.

The nanofiber filter according to the present invention can be applied to and used in all types of applications, such as face masks, protective clothing or protective clothing, dust-proof nets, air purifiers, various electronic products such as air conditioners, automobiles, ventilation air filters, transportation air filters, industrial filters, clean room facilities, etc., and its scope of use is not limited to the area of silk air filters.

The present invention described above is not limited to the present embodiment and the attached drawings, and various substitutions, modifications, and changes are possible within the scope that does not depart from the technical spirit of the present invention, which will be apparent to those skilled in the art to which the present invention pertains.

(1)--First mesh layer (2)--Nano fiber layer (3)--Second mesh layer

Claims (14)

a) a step of introducing the first mesh layer into an electrospinning device;
b) a step of forming a nanofiber layer by electrospinning a polyvinylidene fluoride (PVDF) solution on the first mesh layer;
c) A step of initially coating the upper surface of the nanofiber layer and the lower surface of the second mesh layer with an eco-friendly water-based adhesive using a roller;
d) A step of winding the nanofiber layer and the second mesh layer onto a pipe or drum, respectively, and then leaving them at room temperature for 2 to 6 hours to allow the first-coated water-based adhesive to permeate into the nanofiber layer and the second mesh layer;
e) A step of finishing coating the upper surface of the nanofiber layer with an eco-friendly water-based adhesive using a roller;
f) A step of thermally pressing and bonding the first mesh layer and the second mesh layer, which are coated with an eco-friendly water-based adhesive, by passing them between upper and lower rollers heated to a temperature of 60 to 90°C;
g) a step of complete drying at room temperature for 48 to 96 hours; including;
The above water-based adhesive contains 5 to 15 wt% of water, 10 to 22 wt% of water-based EVA copolymer, 65 to 75 wt% of water-based acrylic copolymer, and 2 to 5 wt% of VOC reducing agent.
A method for manufacturing a nanofiber filter characterized in that the above VOC reduction agent is an aqueous solution containing 69 to 90 wt% of water, 4 to 12 wt% of thiourea, 1 to 4 wt% of urea, and 1 to 4 wt% of boric acid. a`) A step of initially coating the upper surface of the first mesh layer with an eco-friendly water-based adhesive using a roller;
b`) A step of naturally drying at room temperature so that the moisture content of the first coated mesh layer is maintained at 40 to 60%;
c) a step of introducing the first mesh layer into the electrospinning device;
d`) a step of forming a nanofiber layer by electrospinning a polyvinylidene fluoride (PVDF) solution on the first mesh layer;
e`) A step of coating an eco-friendly water-based adhesive on the upper surface of the nanofiber layer and the lower surface of the second mesh layer using a roller;
f`) A step of winding the nanofiber layer and the second mesh layer onto a pipe or drum respectively and then leaving them at room temperature for 2 to 6 hours to allow the coated water-based adhesive to permeate into the nanofiber layer and the second mesh layer;
g`) A step of finishing coating the upper surface of the nanofiber layer with an eco-friendly water-based adhesive using a roller;
h`) A step of thermally pressing and bonding the nanofiber layer and the second mesh layer by passing them between upper and lower rollers heated to a temperature of 60 to 90°C;
i`) a step of obtaining a nanofiber filter by completely drying at room temperature for 48 to 96 hours; including;
The above water-based adhesive contains 5 to 15 wt% of water, 10 to 22 wt% of water-based EVA copolymer, 65 to 75 wt% of water-based acrylic copolymer, and 2 to 5 wt% of VOC reducing agent.
A method for manufacturing a nanofiber filter characterized in that the above VOC reduction agent is an aqueous solution containing 69 to 90 wt% of water, 4 to 12 wt% of thiourea, 1 to 4 wt% of urea, and 1 to 4 wt% of boric acid. In claim 1 or claim 2;
Instead of step g) or step i`) of obtaining a nanofiber filter by completely drying at room temperature for 48 to 96 hours, a step of drying with heating in a drying room at 60 to 90°C for 12 to 24 hours and then completely drying at room temperature for 12 to 24 hours to obtain a nanofiber filter;
A method for manufacturing a nanofiber filter comprising: In claim 1 or claim 2;
A method for manufacturing a nanofiber filter, characterized in that the coating amount of the above-mentioned water-based adhesive is 8 to 30 g/㎡. delete delete In claim 1 or claim 2;
A method for manufacturing a nanofiber filter further comprising 1 to 10 wt% of adipic dihydrazide. In claim 1 or claim 2;
Contains an additional 2 to 8 wt% of a water-repellent agent,
A method for manufacturing a nanofiber filter, characterized in that the water-repellent liquid is either an environmentally friendly fluorine-based water-repellent liquid or a silicone-based water-repellent liquid. In claim 1 or claim 2;
A method for manufacturing a nanofiber filter having a glass transition temperature of -25 to 0°C and a viscosity of 300 to 800 cps. A nanofiber filter manufactured by the manufacturing method of any one of claims 1 or 2. A nanofiber filter manufactured by the manufacturing method of any one of claims 1 or 2, wherein the nanofiber layer is transparent white and has a transparency of 70 to 90%. A nanofiber filter manufactured by the manufacturing method of any one of claims 1 or 2, characterized in that it is one of a mask, a hat, gloves, a dust-proof suit, a protective suit, a dust-proof net, an air purifier, an air filter for ventilation, an air filter for transportation, and an industrial filter. A first mesh layer composed of a fiber mesh of a predetermined mesh;
A nanofiber layer electrospun and bonded using a polyvinylidene fluoride (PVDF) solution on the upper surface of the first mesh layer;
A second mesh layer is bonded to the upper surface of the nanofiber layer and is composed of a fiber mesh of a predetermined mesh;
The air permeability of the above nanofiber layer is 80 to 150 cfm.
The basis weight of the above nanofiber layer is 0.05 to 0.5 gsm,
The above first mesh layer has a mesh size of 6,400 to 10,000 and a weight of 15 to 30 gsm.
The above second mesh layer has a mesh of 1,225 to 3,025 and a weight of 40 to 55 gsm.
A nanofiber filter characterized in that the first mesh layer, the nanofiber layer, and the second mesh layer are bonded with a water-based adhesive having a coating amount of 8 to 30 g/㎡, and the water-based adhesive is an environmentally friendly water-based adhesive containing 5 to 15 wt% of water, 10 to 22 wt% of an water-based EVA copolymer, 65 to 75 wt% of an water-based acrylic copolymer, and 2 to 5 wt% of a VOC reduction agent. In claim 13;
A nanofiber filter having a color of the above nanofiber layer that is transparent white and has a transparency of 70 to 90%.