KR102119477B1 - Filter media, method for manufacturing thereof and Filter unit comprising the same - Google Patents

Abstract

Filter media is provided. The filter medium according to an embodiment of the present invention includes a porous first support; A nanofiber web that is stacked on each of the upper and lower portions of the first support and has a tensile strength in the MD (Mechanical Direction) direction greater than a tensile strength in the TD (Transverse Direction) direction; And a porous second support interposed between the first support and the nanofiber web. According to this, since the nanofiber web of the filter medium according to the present invention has excellent mechanical strength, the shape or structure deformation and damage of the filter medium in the water treatment process is minimized, and the flow path can be smoothly secured to have a high flow rate. In addition, the filter media of the present invention ensures excellent durability of the filter media even under high pressure applied when backwashing, has an extended use cycle, and at the same time efficiently controls contamination and has excellent water permeability, thus in various water treatment fields. It can be applied in various ways.

Description

Filter media, its manufacturing method and filter unit comprising the same{Filter media, method for manufacturing thereof and Filter unit comprising the same}

The present invention relates to a filter medium, and more particularly, to a filter medium, a manufacturing method thereof and a filter unit including the same.

The separation membrane may be classified into a microfiltration membrane (MF), an ultrafiltration membrane (UF), a nano separation membrane (NF), or a reverse osmosis membrane (RO) according to the pore size.

The separators exemplified above have differences in use and pore size, but they have in common that they are filter media formed from fibers or porous polymer filter media, or they have a composite membrane shape.

The porous polymer filtration medium is formed through a method such as sintering the pore-forming agent through a separate pore-forming agent included in the crude liquid or dissolving it in an external coagulating solution through pores formed inside the polymer membrane or the polymer hollow fiber. It is common. On the other hand, the filter medium formed from the fibers is generally produced by accumulating the produced short fibers and then applying heat/pressure or the like, or by simultaneously applying heat/pressure or the like during spinning.

A typical example of a filter medium formed from the fibers is a non-woven fabric, and the pores of the non-woven fabric are usually adjusted to the diameter of the short fibers and the basis weight of the media. However, since the diameter of the short fibers included in the general nonwoven fabric is a micro unit, there is a limitation in realizing a separation membrane having a fine and uniform pore structure by only adjusting the fiber diameter and basis weight. Only a separation membrane of the degree can be realized, and a separation membrane such as an ultrafiltration membrane and a nano-separation membrane for filtering finer particles has been difficult to implement.

A method designed to solve this is a separation membrane manufactured through ultra-fine fibers having a nano-diameter fiber. However, microfibers having a nano-unit diameter are difficult to be produced by only one spinning in a fiber spinning process such as wet wet spinning, and after spinning with sea-island yarn, the sea component is separately eluted to obtain the ultrafine fiber island component. There is a hassle to do, an increase in cost, and an extension of production time. Accordingly, in recent years, there is a tendency to manufacture a lot of filter media formed from fibers by directly spinning fibers having a diameter of nanometers through electrospinning.

On the other hand, some of the various foreign matters contained in the water to be treated may remain in the pores of the filter medium after the water treatment process is repeatedly performed, or an adhesive layer may be formed on the surface of the filter medium. there is a problem. In order to solve this, it is possible to think of a method of preventing the occurrence of the above-described fouling phenomenon through pre-treatment or a method of washing the filter medium in which a fouling phenomenon has already occurred. It is common to remove foreign substances remaining in the filter medium by applying a high pressure to the filter medium so that it is in the opposite direction to the inflow, filtration and outflow paths. However, the high pressure applied when washing the filter medium may cause damage to the filter medium, and in the case of a filter medium formed of a multi-layer structure, problems of separation between layers may occur.

In particular, the filter medium formed of nano-unit-diameter fibers is very weak in mechanical strength and cannot be easily damaged because it cannot withstand the pressure applied to the media during filtration or the higher pressure applied during backwashing. In order to compensate for the mechanical strength of these nano-unit fibers, even when a separate supporting member is further provided, when the filter medium is compressed by the applied pressure, the pressure applied to the filter medium increases as the flow path inside the filter medium closes, and the flow rate decreases significantly. there is a problem.

Accordingly, even in the backwashing process performed at high pressure, the shape or structure deformation and damage of the filter medium are minimized, and the flow path is secured, thus developing a filtration medium that has a high flow rate and a fast processing speed and exhibits mechanical properties of a certain level or higher. This is an urgent situation.

Registered Patent Publication No. 10-0871440

The present invention has been devised in view of the above points, and has an object to provide a filter medium having high efficiency and high lifespan and a method for manufacturing the same, with mechanical properties of a certain level or more secured.

In addition, it is an object of the present invention to provide a filter medium having a high flow rate and a high processing speed and a method for manufacturing the filter medium while minimizing the shape, structure deformation, and damage of the filter medium during water treatment operation.

In addition, another object of the present invention is to provide a filter material having excellent durability and a method for manufacturing the same, which can ensure a flow path even at high pressure applied in a backwashing process and minimize separation between layers and damage to the membrane.

In addition, another object of the present invention is to provide a flat type filter unit and a filter module that can be variously applied in the field of water treatment through a filter medium having excellent water permeability and durability.

In order to solve the above problems, the present invention is a porous first support; A nanofiber web that is stacked on each of the upper and lower portions of the first support and has a tensile strength in the MD (Mechanical Direction) direction greater than a tensile strength in the TD (Transverse Direction) direction; And a porous second support interposed between the first support and the nanofiber web.

According to an embodiment of the present invention, the tensile strength in the TD (Transverse Direction) direction and the tensile strength in the MD (Mechanical Direction) direction of the nanofiber web may have a tensile strength ratio of 1: 1.2 to 6.5.

In addition, the tensile strength in the MD direction of the nanofiber web may be 0.8 ~ 7.0 kg / ㎟.

In addition, the tensile strength in the TD direction of the nanofiber web may be 0.3 ~ 5.0 kg / ㎟.

In addition, in the nanofiber web, the values of Equation 1 and Equation 2 below may be 0.1 or less, respectively.

[Equation 1]

(Standard deviation of tensile strength in MD direction) / (Average tensile strength in MD direction)

[Equation 2]

(Standard deviation of the tensile strength in the TD direction) / (Average tensile strength in the TD direction)

In addition, the average fiber diameter of the nanofibers may be 0.05 ~ 1㎛.

In addition, the average pore size of the nanofiber web may be 100 ~ 5000nm.

In addition, the nanofiber web may have a porosity of 40 to 90%, a basis weight of 0.05 to 20 g/m 2 and a thickness of 0.5 to 200 μm.

In addition, the first support and the second support may each independently be any one or more selected from the group consisting of non-woven fabric, fabric and knitted fabric.

In addition, the first support may have a basis weight of 250 to 800 g/m 2, the thickness may be 2 to 8 mm, and the second support may have a basis weight of 35 to 100 g/m 2 and a thickness of 100 to 400 μm. Can be

In addition, the second support includes a second composite fiber disposed to expose at least a portion of the low-melting component, including a supporting component and a low-melting component, to the outer surface, and the low-melting component of the second composite fiber is nano It can be fused to the fibrous web.

In addition, the first support includes a first composite fiber disposed to expose at least a portion of the low-melting component, including a supporting component and a low-melting component, to the outer surface, and the low-melting component and the first 2 The first support and the second support can be joined by fusion between the low-melting component of the composite fiber.

Further, the average fiber diameter of the first support body may be 5 to 50 μm, and the average fiber diameter of the second support body may be 5 to 30 μm.

In addition, the present invention, (1) laminating the nanofiber web and the second support; And (2) placing and laminating the laminated nanofiber web and the second support on both sides of the first support so that the second support comes into contact with the first support. It provides a method for manufacturing a filter medium having a tensile strength in the direction greater than the tensile strength in the TD (Transverse Direction) direction.

According to an embodiment of the present invention, the step (1) may be applied to any one or more of heat and pressure after electrospinning nanofibers on one surface of the second support to bond the nanofiber web and the second support.

In addition, the present invention is the filter medium described above; It provides a flat filter unit comprising; and a support frame for supporting the rim of the filter medium; and a flow path for allowing the filtrate filtered from the filter medium to flow out.

According to the present invention, since the nanofiber web of the filter medium according to the present invention has excellent mechanical strength, the shape or structure deformation and damage of the filter medium in the water treatment process is minimized, and the flow path can be smoothly secured to have a high flow rate.

In addition, the filter media of the present invention ensures excellent durability of the filter media even under high pressure applied when backwashing, has an extended use cycle, and at the same time efficiently controls contamination and has excellent water permeability, thus in various water treatment fields. It can be applied in various ways.

1 is a cross-sectional view of a filter medium according to an embodiment of the present invention,
Figure 2 is a backwashing process after the separation of the layer inside the filter medium, the washing liquid is trapped inside the filter medium, the picture of the filter medium is swollen,
FIG. 3 is a schematic view of the present invention for laminating a filter media according to an embodiment, showing that the nanofiber web and the second support are laminated;
4A to 4B are views of a nanofiber web included in an embodiment of the present invention, FIG. 4A is a surface electron micrograph of the nanofiber web, and FIG. 4B is a cross-section electron micrograph of the nanofiber web,
Figure 5 is a cross-sectional electron micrograph of a second support having a nanofiber web on one side included in an embodiment of the present invention, and
6 is a view of a flat filter unit according to an embodiment of the present invention, FIG. 6A is a perspective view of a filter unit, and FIG. 6B is a schematic view showing a filtration flow based on a cross-sectional view of the XX' boundary of FIG. 6A.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art to which the present invention pertains can easily practice. The present invention can be implemented in many different forms and is not limited to the embodiments described herein. In the drawings, parts not related to the description are omitted in order to clearly describe the present invention, and the same reference numerals are added to the same or similar elements throughout the specification.

As shown in Figure 1, the filter medium 1000 according to an embodiment of the present invention is a porous first support 130; Nanofiber webs 111 and 112 stacked on upper and lower portions of the first support; And a porous second support (121, 122) interposed between the first support and the nanofiber web.

The nanofiber webs 111 and 112 are responsible for filtration of the water to be treated, and may be a three-dimensional network structure formed by stacking a plurality of nanofibers 111a randomly in three dimensions (see FIGS. 4A and 4B ).

In general, as the filter media repeats the water treatment process, foreign matter contained in the water to be treated adheres to the filter media to form an adhesion layer or is embedded in the filter media to block the flow path and degrade the filtration function. When replacing the filter media, there is a problem that the cost of water treatment increases. Accordingly, in order to prolong the use period of the filter medium, it is necessary to periodically perform a washing process to apply a physical stimulus to the filter medium to remove foreign substances stuck in or stuck to the filter medium, which is called backwashing. Typically, backwashing removes foreign substances attached to or stuck to the filter media by strongly washing water or blowing air in a direction opposite to the filtration direction of the filter media, while supplying washing water and/or air to the filter media and simultaneously In order to remove, it is necessary to supply washing water or air at a pressure higher than the pressure applied to the filter medium in the filtration process.

However, in the case of a filter medium in which nano-fiber microfibers are implemented in the form of a nanofiber web, the mechanical strength is low compared to a filter medium implemented in the form of a general non-woven fabric, and thus it is highly likely to damage the nanofiber web during water treatment operation. Nanofibers may not be able to withstand high pressures due to a backwash, and nanofibers may be trimmed or partially deformed. As a result, mechanical strength of the nanofiber webs may be further deteriorated, resulting in a problem that stability and durability of the filter media cannot be guaranteed. .

Accordingly, the filter media according to the present invention has the tensile strength that the nanofiber webs 111 and 112 satisfy a certain level, thereby trimming or deforming the nanofibers during a water treatment operation as well as a backwashing process performed at a higher pressure. According to the nano-fiber web (111,112) to implement a filter medium to prevent the degradation of the mechanical strength.

To this end, the tensile strength in the direction of MD (Mechanical Direction) of the nanofiber webs 111 and 112 provided in the filter medium 1000 according to the present invention is implemented to be greater than the tensile strength in the direction of TD (Transverse Direction). The tensile strength in the MD (Mechanical Direction) direction refers to the tensile strength of the nanofiber web relative to the direction in which the nanofibers are emitted, and the tensile strength in the TD (Transverse Direction) direction is the transverse direction in the MD direction, that is, the nanofibers It means the tensile strength in the direction perpendicular to the direction from which it is emitted. In addition, the tensile strength of the nanofiber web refers to the maximum strain that can withstand without breaking when the tensile force in the MD or TD direction acts on the nanofiber web.

At this time, the tensile strength in the TD direction and the tensile strength in the MD direction do not act as independent factors for determining the mechanical strength of the nanofiber web, and the tensile strength in the TD direction and the tensile strength in the MD direction are water treatment for the filter medium. They can affect each other while driving. For example, in the nanofiber web according to the present invention, since there are pores formed at the intersection of a plurality of strands of nanofibers, a concentrated stress phenomenon in which local stress is applied around the pores due to tensile force in the TD direction or MD direction This may occur, and the pores formed of a plurality of strands of nanofibers have different pore sizes, and thus strains due to stress concentration may be different from each other. Furthermore, since the filtrate is not filtered only in a constant direction in the transverse direction or in the longitudinal direction, it is possible to realize nanofibers having excellent mechanical strength by simultaneously controlling the tensile strength in the TD direction or MD direction.

In addition, in general, the fiber web formed through electrospinning has the same value as the tensile strength in the TD direction and the tensile strength in the MD direction because the fibers have no directionality. In this case, when backwashing to filter the washing water of high pressure in the direction opposite to the filtration direction of the filtrate, there is a fear that the fiber web is easily damaged by the pressure higher than the tensile strength in the MD direction and the tensile strength in the TD direction. In particular, in the case of constructing a fiber web using ultra-fine fibers of nano-units, it is difficult to expect an improvement in tensile strength through entanglement between microfibers, thereby increasing the mechanical strength of the fiber web at high pressure due to the filtration process and backwashing. Additional support members or additional processes are required to supplement.

However, since the nanofiber webs 111 and 112 according to the present invention are implemented to have a tensile strength in the MD direction greater than the tensile strength in the TD direction, the nanofiber web ( 111, 112) can prevent physical property degradation according to the mechanical strength. More specifically, the nanofiber webs 111 and 112 according to the present invention are provided with straightness in the MD direction formed in the radial direction by a manufacturing process described below, compared to TD nanofibers having no directivity. Many entanglements are created. Due to this, the tensile strength in the MD direction may have a higher value than the tensile strength in the TD direction. In this case, even if a stronger pressure is applied to the nanofiber webs 111 and 112 than the tensile strength of the nanofibers in the TD direction, Mechanical denaturation of the nanofiber webs 111 and 112 is not induced unless a backwash pressure higher than the tensile strength in the MD direction is applied. That is, since the above-described stress concentration phenomenon can be dispersed in the TD direction and the MD direction, deformation due to a decrease in mechanical strength of the nanofiber webs 111 and 112 can be minimized.

In addition, according to an embodiment of the present invention, the tensile strength in the TD direction and the tensile strength in the MD direction of the nanofiber webs 111 and 112 may have a tensile strength ratio of 1: 1.2 to 6.5, preferably 1.5 to 5.0. have. If the tensile strength ratio between the tensile strength in the TD direction and the tensile strength in the MD direction of the nanofiber webs 111 and 112 is less than 1: 1.2, the nanofiber webs cannot withstand pressure when backwashing, or bend or form nanofiber webs The filtrate may break, resulting in deterioration of the durability and stability of the filter medium, and when the tensile strength ratio exceeds 1: 6.5, the filtrate is in the TD direction because the tensile strength in the TD direction is too weak compared to the tensile strength in the MD direction. When processed, damage to the nanofibers arranged in the TD direction may occur or may be trimmed to cause mechanical deformation of the nanofiber web.

In addition, the tensile strength in the MD direction of the nanofiber webs 111 and 112 may be 0.8 to 7.0 kg/mm 2, preferably 1 to 6.5 kg/mm 2. In addition, the tensile strength in the TD direction may be 0.3 to 5.0 kg/㎟, and preferably 0.5 to 4 kg/㎟. If the tensile strength in the MD direction is less than 0.8 kg/㎟, or the tensile strength in the TD direction is less than 0.3 kg/㎟, the mechanical strength according to the tensile strength of the nanofiber web is weak, so there is a possibility that it is easily deformed by an external tensile force. . In addition, if the tensile strength in the MD direction exceeds 7 kg/㎟ or the tensile strength in the TD direction exceeds 5 kg/㎟, the backwash durability may deteriorate as the flexibility of the nanofiber web decreases.

On the other hand, the tensile strength of the nanofiber webs 111 and 112 forming the filtration medium is affected by various factors such as the basis weight of the nanofiber webs, the diameter and fineness of the nanofibers, and the porosity and pore size formed at the intersection of the nanofibers. Therefore, there is a variation for each specific portion of the nanofiber webs 111 and 112. Since such a variation in tensile strength can affect the durability and mechanical strength of the nanofiber web, it is desirable to minimize the variation in a specific portion of the nanofiber web (111, 112).

Accordingly, in the nanofiber webs 111 and 112 according to an embodiment of the present invention, the values of Equation 1 and Equation 2 below may be 0.1 or less, and preferably 0.05 or less.

[Equation 1]

(Standard deviation of tensile strength in MD direction) / (Average tensile strength in MD direction)

[Equation 2]

(Standard deviation of the tensile strength in the TD direction) / (Average tensile strength in the TD direction)

At this time, the average tensile strength in the MD direction is measured by measuring the tensile strength of the central portion of the first region to the tenth region formed by dividing the nanofiber webs 111 and 112 in parallel to the radial direction, and the average value thereof. , The average tensile strength in the TD direction is measured by measuring the tensile strength of the central portion of the first to tenth regions formed by dividing the nanofiber webs 111 and 112 in parallel to the vertical direction in the radial direction, and averaging them. do.

In addition, the standard deviation of the tensile strength in the MD direction is obtained by subtracting the average tensile strength in the MD direction from the values of the central partial tensile strength in each of the first to tenth regions according to the MD direction squared by each'deviation'. It means the value calculated by applying the square root to the'dispersion' calculated by measuring the average value, and the standard deviation of the tensile strength in the TD direction is the central partial tensile strength value of each of the first to tenth regions along the TD direction. In, it means the value calculated by applying the square root to the'variance' calculated by measuring the average value after squaring each'deviation' minus the average tensile strength in the MD direction.

Specifically, the standard deviation and the average tensile strength of the tensile strength in the MD direction are cut into nanofiber webs in the width × length of 250 mm × 150 mm, and divided into 10 equal parts in the MD direction to measure the width × height of 25 mm × 150 mm. After measuring, the standard deviation of the tensile strength in the TD direction and the average tensile strength were cut by cutting the nanofibrous web into horizontal × vertical 150 mm × 250 mm, and dividing it into 10 equal parts in the TD direction to horizontal × vertical 150 mm × 25 It shows what was measured after manufacturing the specimen of mm.

If the values of Equation 1 and Equation 2 exceed 0.1, the tensile strength values of a specific portion of the nanofiber webs 111 and 112 are non-uniform, and thus the mechanical strength of the nanofibrous webs 111 and 112 and Durability may not be secured, and reliability of the filter medium produced through this may be reduced.

In addition, the average fiber diameter of the plurality of nanofibers 111a forming the nanofiber webs 111 and 112 may be 0.05 to 1 μm, preferably the average fiber diameter of 0.1 to 0.9 μm. If the average fiber diameter of the nanofibers is less than 0.05 µm, the flow rate may decrease, and smooth backwashing may be difficult as a separation phenomenon of the separation membrane due to an increase in differential pressure, as shown in FIG. 2. The function may be significantly reduced or completely lost. If it exceeds 1 μm, the bonding force with the second support member, which will be described later, may decrease, and filtration efficiency may decrease.

In addition, the average pore size of the nanofiber webs 111 and 112 may be 100 to 5000 nm, preferably 100 to 3000 nm, and more preferably 100 to 350 nm. If the average pore size of the nanofiber web is less than 100 nm, the diameter of the nanofibers for realizing it must also be very small. It is very difficult to form a web having pores of less than 100 nm average pore size due to radiation technology, and due to an increase in differential pressure Smooth backwashing can be difficult. In addition, if the average pore size of the nanofiber web exceeds 5000 nm, the diameter of the nanofibers for realizing this must be increased. When the pores are formed by stacking the fibers in three dimensions at random, the pore size distribution is very high. As it is difficult to implement narrowly, and it is easy to form a web having a wide pore distribution, it is difficult to achieve the properties desired by the present invention, and accordingly, the filtration efficiency may be reduced.

In addition, the above-described nanofiber webs 111 and 112 may have a thickness of 0.5 to 200 μm, preferably a thickness of 1 to 150 μm, and may be, for example, 20 μm. If the thickness of the nanofiber webs 111 and 112 is less than 0.5 μm, filtration efficiency and/or durability of backwashing may be deteriorated, and when the thickness exceeds 200 μm, smooth backwashing due to an increase in differential pressure may be difficult.

In addition, the nanofiber webs 111 and 112 may have a basis weight of 0.05 to 20 g/m 2, preferably a basis weight of 5 to 15 g/m 2, and for example, 10 g/m 2. If the basis weight of the nanofiber web is less than 0.05 g/m 2, the filtration efficiency may decrease, and the backwash durability may decrease as the bonding strength with the second support decreases, and if the basis weight exceeds 20 g/m 2 It may be difficult to secure a flow rate of the above level, and smooth backwashing may be difficult due to increased differential pressure.

Further, the porosity of the nanofiber webs 111 and 112 is 40 to 90%, and more preferably 60 to 90%.

The nanofibers 111a forming the nanofiber webs 111 and 112 may be formed of known fiber-forming components. However, preferably, a fluorine-based compound may be included as a fiber-forming component in order to express excellent chemical resistance and heat resistance. Through this, even if the water to be treated is a strong acid/strong base solution or a high temperature solution, the desired level without changing the properties of the filter medium As a result, it has the advantage of securing filtration efficiency/flow rate and having a long use cycle. The fluorine-based compound may be used without limitation in the case of a known fluorine-based compound that can be made of nanofibers, for example, polytetrafluoroethylene (PTFE)-based, tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer ( PFA) system, tetrafluoroethylene-hexafluoropropylene copolymer (FEP) system, tetrafluoroethylene-hexafluoropropylene-perfluoroalkyl vinyl ether copolymer (EPE) system, tetrafluoroethylene-ethylene copolymer Contains any one or more compounds selected from the group consisting of coalescence (ETFE), polychlorotrifluoroethylene (PCTFE), chlorotrifluoroethylene-ethylene copolymer (ECTFE) and polyvinylidenefluoride (PVDF) It may be, more preferably, the manufacturing cost is low, and mass production of nanofibers is easy through electrospinning, and it may be polyvinylidene fluoride (PVDF) in terms of excellent mechanical strength and chemical resistance. At this time, when the nanofibers include PVDF as a fiber-forming component, the weight average molecular weight of the PVDF may be 10,000 to 1,000,000, and preferably 300,000 to 600,000, but is not limited thereto.

Meanwhile, the nanofibers forming the nanofiber webs 111 and 112 may be modified to increase hydrophilicity, and for example, a hydrophilic coating layer may be further provided on at least a portion of the outer surface of the nanofibers. If the nanofibers contain a fluorine-based compound as described above, the fluorine-based compound is very hydrophobic and thus the flow rate may not be good when the filtrate is a hydrophilic solution. To this end, a hydrophilic coating layer may be further provided on the surface of the hydrophobic nanofiber, and the hydrophilic coating layer may be known, for example, formed by including a hydrophilic polymer having a hydroxyl group, or the hydrophilic polymer is crosslinked through a crosslinking agent. Can be formed. As an example, the hydrophilic polymer may be a single or mixed form of polyvinyl alcohol (PVA), ethylene vinyl alcohol (EVOH), sodium alginate, and most preferably polyvinyl alcohol. (PVA). In addition, the crosslinking agent can be used without limitation in the case of a known crosslinking agent having a functional group that can be crosslinked through a condensation reaction with a hydroxyl group of the hydrophilic polymer. In one example, the functional group may be a hydroxy group, a carboxy group, or the like.

The hydrophilic coating layer may be formed by crosslinking a crosslinking agent including polyvinyl alcohol (PVA) and a carboxyl group for more improved physical properties. The polyvinyl alcohol may have a polymerization degree of 500 to 2000, and a saponification degree of 85 to 90%. When the degree of polymerization of the polyvinyl alcohol is excessively low, the formation of the hydrophilic coating layer may not be smooth or may be easily peeled off even if it is formed, and the hydrophilicity may not be improved to a desired level. In addition, when the degree of polymerization is too large, formation of the hydrophilic coating layer may be excessive, and accordingly, the pore structure of the nanofiber web may be changed or pores may be closed. In addition, if the degree of saponification is too low, it may be difficult to improve hydrophilicity.

The crosslinking agent may be a component containing a carboxyl group so as to be crosslinked with the aforementioned polyvinyl alcohol. In one example, the crosslinking agent may include at least one material selected from the group consisting of poly(acrylic acid-maleic acid), polyacrylic acid and poly(styrenesulfonic acid-maleic acid). In addition, the coating/adhesiveness on the surface of nanofibers with improved hydrophobicity and a very thin coating so that there is no change in the pore structure of the nanofiber webs 111 and 112, and at the same time, the crosslinking agent has at least three or more carboxy groups in order to express an improved flow rate. It may be a multifunctional crosslinking agent comprising a. If the number of carboxyl groups of the crosslinking agent is less than 3, it is difficult to form a coating layer on the surface of the hydrophobic nanofiber, and even if it is formed, the adhesion is very weak and can be easily peeled off. For example, a crosslinking agent having three or more carboxyl groups may be poly(acrylic acid-maleic acid).

The hydrophilic coating layer may be formed by crosslinking 2 to 20 parts by weight of a crosslinking agent containing a carboxyl group relative to 100 parts by weight of the polyvinyl alcohol. If the crosslinking agent is provided in less than 2 parts by weight, the formability of the hydrophilic coating layer may be lowered, and chemical resistance and mechanical strength may be lowered. In addition, if the crosslinking agent is provided in excess of 20 parts by weight, the flow rate may be reduced due to reduced pores due to the coating layer.

Meanwhile, the hydrophilic coating layer may be formed on part or all of the outer surface of the nanofiber. At this time, the hydrophilic coating layer may be coated with nanofibers to include 0.1 to 2 g per unit area (m 2) of the nanofiber web.

As described above, the wetting angle of the surface of the nanofiber webs 111 and 112 modified to have a hydrophilic coating layer may be 30° or less, more preferably 20° or less, even more preferably 12° or less, and more preferably It may be 5° or less, and through this, despite being a fiber web made of hydrophobic nanofibers, it has an advantage of ensuring an improved flow rate.

Meanwhile, the nanofiber webs 111 and 112 may be provided on the filter medium 1000 in more than one layer, and the porosity, pore diameter, basis weight, and/or thickness of each nanofiber web may be different.

Next, the first support 130 will be described.

The first support 130 is responsible for supporting the filter media 1000 and forming a large flow path to smoothly perform the filtration process or backwash process. Specifically, in the filtration process, when a pressure gradient is formed so that the inside is at a lower pressure than the outside of the filter medium, the filter medium may be compressed. In this case, the flow path through which the filtrate can flow inside the filter medium is significantly reduced or blocked. The greater the differential pressure is applied to the filter media, the lower the flow rate can be. Also, in the backwashing process, an external force that expands from the inside of the filter medium toward the outside direction may be applied. When the mechanical strength is low, the filter medium may be damaged due to the external force applied.

The first support 130 is provided to prevent the above problems arising in the filtration process and/or the backwashing process, and is used in the water treatment field, and may be a known porous member that guarantees mechanical strength. The first support may be a non-woven fabric, fabric or fabric.

The fabric means that the fibers included in the fabric have a longitudinal and lateral orientation, and the specific structure may be plain weave, twill, etc., and the density of warp and weft yarns is not particularly limited. In addition, the knitted fabric may be a known knit fabric, a knitted fabric, a knitted fabric, or the like, for example, a yarn may be a knitted yarn tricot (Tricot). In addition, as shown in Figure 1, the first support 130 may be a nonwoven fabric having no longitudinal and lateral orientation to the first composite fiber 130a, and a dry nonwoven fabric or a wet nonwoven fabric such as a chemical bonding nonwoven fabric, a thermal bonding nonwoven fabric, or an airlay nonwoven fabric, Known nonwoven fabrics manufactured by various methods such as spanless nonwoven fabric, needle punching nonwoven fabric, or melt blown can be used.

The first support 130 may have a thickness of 2 to 8 mm, more preferably 2 to 5 mm, and even more preferably 3 to 5 mm to express sufficient mechanical strength. If the thickness is less than 2 mm, it may not develop sufficient mechanical strength to withstand frequent backwashing. In addition, when the thickness exceeds 8 mm, when the filter media is implemented as a filter unit to be described later, and when a plurality of filter units are implemented as a filter module in a limited space, the degree of integration of the filter media per unit volume of the module may decrease, and the differential pressure Smooth backwashing due to the increase can be difficult.

Further, the first support 130 may have a basis weight of 250 to 800 g/m 2, more preferably 350 to 600 g/m 2. If the basis weight is less than 250 g/㎡, it may be difficult to develop sufficient mechanical strength, and the adhesion with the second support may be reduced, and if the basis weight exceeds 800 g/㎡, the flow rate may not be sufficient to form a sufficient flow path. It decreases, and smooth backwashing due to increased differential pressure may be difficult.

In addition, when the first support 130 is formed of a fiber such as a non-woven fabric, the average diameter of the fiber may be 5 to 50 μm, preferably 20 to 50 μm, and more preferably 25 to 40 μm. Can be If the average diameter of the fibers of the first support 130 is less than 5 μm, the flow rate may decrease, smooth backwashing due to an increase in differential pressure may be difficult, and when it exceeds 50 μm, it may be difficult to develop sufficient mechanical strength. , Filtration efficiency may be reduced, and adhesion with the second support may be reduced.

In addition, the first support 130 may have an average pore size of 20 ~ 200㎛, preferably an average pore size of 30 ~ 180㎛, for example, the average pore size may be 100㎛, porosity is 50 ~ 90%, preferably may be 55 ~ 85%, for example, porosity may be 70%, but is not limited thereto, and supports the nanofiber webs 111 and 112 in a filtration process and/or a backwash process. There is no limitation as long as it expresses a desired level of mechanical strength and has a porosity and a pore size sufficient to smoothly form a flow path even under high pressure.

When the first support 130 is a material that can be used as a support for a separator, there is no limitation in the material. As a non-limiting example, synthetic polymer components selected from the group consisting of polyester-based, polyurethane-based, polyolefin-based and polyamide-based; Alternatively, a natural polymer component containing cellulose may be used. However, when the first support has a brittle physical property, it may be difficult to expect a desired level of bonding strength in the process of laminating the first support and the second support, which means that the first support has a smooth surface like a film. In addition, the surface may be macroscopically uneven while forming porosity, and the surface formed of fibers such as a non-woven fabric may not have a smooth surface depending on the arrangement of fibers, the fineness of fibers, etc., and the degree may be different according to location. to be. If the rest of the parts are joined with the non-adherent part present at the two interlayer interfaces, the interlayer separation may start due to the non-adherent part. In order to solve this, it is necessary to perform a lamination process in a state in which the adhesion degree of the two layers is increased by applying pressure from both sides of the layer, but in the case of a support having a strong physical property, the adhesion of the interface between the two layers is maintained even when pressure is applied. There is a limit to increase, and when a greater pressure is applied, the support may be damaged, so the material of the first support has good flexibility, a material with high elongation may be suitable, and preferably has excellent adhesion with the second support (121,122). So that the first support 130 may be a polyolefin-based material.

On the other hand, the first support 130 may include a low melting point component to be bound with the second support (121,122) without a separate adhesive or adhesive layer. When the first support 130 is a non-woven fabric, it may be made of a first composite fiber 130a including a low melting point component. The first composite fiber 130a may be disposed such that at least a portion of the low-melting component is exposed on the outer surface, including a supporting component and a low-melting component. For example, a sheath-core composite fiber in which a support component forms a core portion and a low melting point component forms a sheath surrounding the core portion, or a side-by-side composite fiber in which a low melting point component is disposed on one side of the support component. Can be The low-melting component and the supporting component may be preferably polyolefin-based in terms of flexibility and elongation of the support as described above, and for example, the supporting component may be polypropylene and the low-melting component may be polyethylene. The melting point of the low melting point component may be 60 ~ 180 ℃.

Next, the second support members 121 and 122 interposed between the above-described first support member 130 and the nanofiber webs 111 and 112 will be described.

The second support (121,122) supports the nanofiber web (111,112), and is responsible for increasing the bonding strength of each layer provided in the filter medium.

The first support 130 is responsible for supplementing the mechanical strength so that the function of the filter medium can be fully secured even in the backwashing process performed at a very high pressure as described above, but the first support 130 itself Even when it has a very high mechanical strength, when the bonding force between the first support 130 and the nanofiber webs 111 and 112 is weakened, the washing liquid introduced into the first support in the backwashing process as shown in FIG. 2 is outside the nanofiber web. As the filter medium expands due to being trapped inside the filter medium without being able to escape, the backwashing efficiency is remarkably reduced, and there is a risk of deterioration/loss as a filter medium by accelerating the interface separation between the first support and the nanofiber web. Particularly, in order to maintain sufficient mechanical strength without interfering with the flow of filtrate through the nanofiber web, the thickness must be thickened while maintaining an appropriate basis weight, and when a thick nonwoven fabric is combined with a thin nanofiber web, heat / When both are applied by applying pressure, the nanofibrous web, which functions as a media due to the heat and pressure applied due to the non-woven fabric, the material melting point of the nanofiber web, and the heat capacity difference, may physically and chemically deform, and the initial It can lead to changes in physical properties such as flow rate and filtration rate of the filter media designed in.

Accordingly, the filter medium 1000' according to an embodiment of the present invention does not directly face the first support 130 and the nanofiber webs 111 and 112, and the second support is thinner than the first support 130. (121,122) can be further interposed, through which the interlayer adhesion process can be performed more stably and easily, expressing a remarkably excellent bonding force at the interface between each layer, and separating layers even when high external force is applied due to backwashing, etc. , It can minimize the peeling problem.

Referring to FIG. 3, as the thickness difference between the second support body 3 and the nanofiber web 2 in the filter medium is significantly reduced, the nanofibrous web 2/second support body 3 is stacked upward, The heat (H1, H2) applied from the bottom may reach the interface between them and it may be easy to form the fused portion (B). In addition, it is easier to control the amount and time of the heat applied compared to the case where there is no second support, which is advantageous for preventing physical/chemical deformation of the nanofiber web 2, so as shown in FIG. 3, the nanofibers on the second support 3 When the web 2 is bonded, there is an advantage in that nanofibers can be combined with excellent adhesion on a support without changing the physical properties of the nanofiber web 2 designed in the initial stage.

The second support (121,122) is not particularly limited as long as it usually serves as a support for the filter media, but in its shape may be preferably a fabric, a knitted fabric or a non-woven fabric. The fabric means that the fibers included in the fabric have a longitudinal and lateral orientation, and the specific structure may be plain weave, twill, etc., and the density of warp and weft yarns is not particularly limited. In addition, the knitted fabric may be a known knitted fabric, and may be a knitted fabric or a knitted fabric, but is not particularly limited thereto. In addition, the non-woven fabric means that there is no longitudinal and lateral orientation of the fibers included, such as dry non-woven fabrics such as chemical bonding non-woven fabrics, thermal bonding non-woven fabrics, air-ray non-woven fabrics, wet non-woven fabrics, spanless non-woven fabrics, needle punching non-woven fabrics, or melt blown It is possible to use a nonwoven fabric prepared by a known method.

The second support (121,122) may be, for example, a non-woven fabric, wherein the fibers forming the second support (121,122) may have an average diameter of 5 ~ 30㎛, preferably 10 ~ 25㎛. If the average diameter of the fibers of the second supports 121 and 122 is less than 5 μm, the flow rate may decrease, and smooth backwashing may be difficult due to an increase in differential pressure, and if it exceeds 30 μm, filtration efficiency may decrease. 1 The adhesion between the support and the nanofiber web may be reduced.

In addition, the second supports 121 and 122 may have a thickness of 100 to 400 μm, preferably 150 to 400 μm, more preferably 150 to 250 μm, and for example, 200 μm. . If the thicknesses of the second supports 121 and 122 are less than 100 μm, filtration efficiency and durability of backwashing may be reduced, and when the thickness exceeds 400 μm, smooth backwashing due to an increase in differential pressure may be difficult.

In addition, the second support (121,122) may have an average pore diameter of 20 ~ 100㎛, porosity may be 50 ~ 90%. However, the present invention is not limited to this, and supports the nanofiber webs 111 and 122 to express a desired level of mechanical strength and at the same time not to inhibit the flow of the filtrate flowing through the nanofiber webs 111 and 122. And, if the pore size is not limited.

In addition, the second support (121,122) may have a basis weight of 35 to 100 g/m 2, more preferably 35 to 75 g/m 2, and for example, 40 g/m 2. If the basis weight is less than 35 g/m 2, the filtration efficiency may be reduced, and the amount of fibers forming a second support distributed at the interface formed with the nanofiber webs 111 and 112 may be small. It may not be possible to express the desired level of binding force due to the reduction of the effective adhesive area of the abutting second support. In addition, sufficient mechanical strength to support the nanofiber web may not be exhibited, and adhesion with the first support may be reduced. In addition, if the basis weight exceeds 100 g/m 2, it may be difficult to secure a desired level of flow rate, and a smooth backwash may be difficult due to an increased differential pressure.

If the second support (121,122) is a material used as a support for the filter media, there is no limitation in the material. As a non-limiting example, synthetic polymer components selected from the group consisting of polyester-based, polyurethane-based, polyolefin-based and polyamide-based; Alternatively, a natural polymer component containing cellulose may be used.

However, the second support (121,122) may be a polyolefin-based polymer component to improve the adhesion between the nanofibrous web (111,112) and the above-described first support (130). In addition, when the second support (121,122) is a non-woven fabric, it may be made of a second composite fiber (121a) containing a low melting point component. The second composite fiber 121a may be disposed such that at least a portion of the low melting point component is exposed on the outer surface, including a supporting component and a low melting point component. For example, a sheath-core composite fiber in which a support component forms a core portion and a low melting point component forms a sheath surrounding the core portion, or a side-by-side composite fiber in which a low melting point component is disposed on one side of the support component. Can be The low-melting component and the supporting component may be preferably polyolefin-based in terms of flexibility and elongation of the support as described above, and for example, the supporting component may be polypropylene and the low-melting component may be polyethylene. The melting point of the low melting point component may be 60 ~ 180 ℃.

The low melting point component of the second composite fiber 121a may be melted by heat/pressure applied in the lamination process to form nanofibrous webs 111 and 112 and a fused portion B, thereby expressing a strong binding force. Can be.

If the above-described first support 130 is implemented as a first composite fiber 130a including a low melting point component in order to express more improved bonding strength with the second support 121, 122, the first support 130 and the first It is possible to form a more robust fusion part due to the fusion of the low melting point component of the first composite fiber 130a and the low melting point component of the second composite fiber 121a at the interface between the two support bodies 121. At this time, the first composite fiber 130a and the second composite fiber 121a may be of the same material in terms of compatibility.

The filter media 1000 described above may be manufactured by a manufacturing method described below, but is not limited thereto.

The filter medium 1000 according to the present invention includes (1) laminating a nanofiber web and a second support; And (2) placing and laminating the laminated nanofiber web and the second support on both sides of the first support so that the second support contacts the first support.

First, as a step (1) according to the present invention, a step of laminating the nanofiber web and the second support is performed.

The nanofiber web may be used without limitation in the case of a method of forming a three-dimensional networked fiber web by providing nanofibers. Preferably, the nanofiber web can form a nanofiber web by electrospinning a spinning solution containing a fluorine-based compound on a second support.

The spinning solution as a fiber-forming component, for example, may include a fluorine-based compound and a solvent. The fluorine-based compound is preferably contained in the spinning solution at 5 to 30% by weight, preferably 8 to 20% by weight, and if the fluorine-based compound is less than 5% by weight, it is difficult to be formed into fibers, and when spinning, it is not spun into fibers and is in a droplet state Even if it is sprayed with to form a film or spinning, a lot of beads are formed and the volatilization of the solvent is not performed well, and thus, pores may be blocked in the calendering process described later. In addition, if the fluorine-based compound exceeds 30% by weight, the viscosity increases and solidification occurs on the surface of the solution, which makes it difficult to spin for a long time, and the fiber diameter may increase to make a fibrous form having a size of less than a micrometer.

The solvent may be used without limitation in the case of dissolving the fluorine-based compound, which is a fiber-forming component, without generating a precipitate, and does not affect the radioactivity of the nanofibers described later, but preferably γ-butyrolactone, cyclohexanone, 3 -Hexanone, 3-heptanone, 3-octanone, N-methylpyrrolidone, dimethylacetamide, acetone dimethylsulfoxide, dimethylformamide. For example, the solvent may be a mixed solvent of dimethylacetamide and acetone.

The prepared spinning solution may be prepared nanofibers through a known electrospinning device and method. As an example, the electrospinning device may use an electrospinning device having a single radiation pack with one radiation nozzle, or a plurality of single radiation packs for mass production, or an electrospinning device with a radiation pack with multiple nozzles. It is also okay. In addition, in the electrospinning method, dry spinning or wet spinning having an external coagulation bath may be used, and there is no limitation according to the method.

When the spinning solution is stirred into the electrospinning device and electrospinning on a collector, for example, paper, a nanofiber web formed of nanofibers can be obtained. However, as described above, in order to impart linearity to the nanofibers spun in the MD direction, an air electrospinning device may be provided outside the spinning nozzle through which the spinning solution is discharged. However, the present invention is not limited thereto, and the nanofibers may be formed to have directionality by a known spinning method including air electrospinning. As an example, the air injection nozzle provided in the nozzle of the spinning pack has an air pressure of air injection. It can be set in the range of 0.01 ~ 0.2MPa. If the air pressure is less than 0.01 MPa, it does not contribute to collection and accumulation, and if it exceeds 0.2 MPa, the phenomenon of clogging the cone of the spinning nozzle and blocking the needle may occur, resulting in radiation trouble. In addition, when spinning the spinning solution, the injection rate of the spinning solution per nozzle may be 10 ~ 30μl/min. In addition, the distance between the tip of the nozzle and the collector may be 10 to 30 cm. However, the present invention is not limited thereto, and may be changed and performed according to the purpose.

Alternatively, the nanofiber web can be directly formed on the second support by directly electrospinning the nanofiber on the second support. The nanofibers accumulated/collected on the second support have a three-dimensional network structure, and heat and/or pressure are required to retain porosity, pore size, basis weight, etc., which are suitable for expressing the desired water permeability and filtration efficiency. By adding it to the accumulated/collected nanofibers, it can be realized as a nanofiber web having a three-dimensional network structure. As a specific method of applying the heat and/or pressure, a known method may be adopted, and as a non-limiting example, a conventional calendering process may be used, and the temperature of the heat applied at this time may be 70 to 190°C. In addition, when performing the calendering process, it may be divided into several steps and performed multiple times. For example, pores after performing a drying process to remove some or all of the solvent and moisture remaining in the nanofibers through primary calendering Secondary calendaring can be performed for adjustment and strength improvement. At this time, the degree of heat and/or pressure applied in each calendering process may be the same or different.

On the other hand, when the second support is made of a low-melting composite fiber, the nanofiber web and the second support can be simultaneously bound through thermal fusion through the calendering process.

In addition, a separate hot melt powder or a hot melt web may be further interposed to bind the second support body and the nanofiber web. At this time, the heat applied may be 60 ~ 190 ℃, the pressure may be applied to 0.1 ~ 10 kgf / ㎠, but is not limited thereto. However, components such as hot-melt powder added separately for binding often generate a fume or melt in a lamination process between supports and supports and nanofibers to close pores, thus achieving the flow rate of the first designed filter media. It may not be possible. In addition, since it can be dissolved in the water treatment process and cause environmentally negative problems, it is preferable to bind the second support and the nanofibrous web without preferably including them.

(1) The second support having the nanofibrous web on one side of the paper by performing the step may have a thickness of about 173±7㎛ as shown in FIG. 5, wherein the size of the scale bar in FIG. 5 is 10㎛ Can be

Next, before performing step (2) described below, the step of forming a hydrophilic coating layer may be further performed by treating the nanofiber web with a composition for forming a hydrophilic coating layer.

Specifically, this step includes the steps of treating a composition for forming a hydrophilic coating layer on a nanofiber web; And heat-treating the hydrophilic coating layer forming composition to form a hydrophilic coating layer.

First, the composition for forming a hydrophilic coating layer may include a hydrophilic component and a crosslinkable component, and may include, for example, a polyvinyl alcohol, a crosslinking agent including a carboxyl group, a solvent dissolving them, and water, for example. The hydrophilic coating layer forming composition may include 2 to 20 parts by weight of a crosslinking agent and 1,000 to 100,000 parts by weight of a solvent relative to 100 parts by weight of polyvinyl alcohol.

On the other hand, when the nanofibers forming the prepared nanofiber web contain a fluorine-based compound, even if the hydrophilic coating layer forming composition described above is processed, the coating layer may not be properly formed on the surface. Accordingly, the hydrophilic coating layer forming composition may further include a wettability improving agent so that the hydrophilic coating layer forming composition wets well on the outer surface of the nanofiber.

The wettability-improving agent may be used without limitation when it is a component capable of improving the wettability to the hydrophilic solution on the outer surface of the hydrophobic nanofiber and at the same time being a component that can be dissolved in the hydrophilic coating layer forming composition. For example, the wettability improving agent may be one or more components selected from the group consisting of isopropyl alcohol, ethyl alcohol and methyl alcohol. In addition, the wettability improving agent may be included in 1,000 to 100,000 parts by weight based on 100 parts by weight of polyvinyl alcohol provided in the hydrophilic coating layer forming composition. If the wettability improving agent is provided in less than 1000 parts by weight, the wettability improvement of the nanofibers is poor, so the formation of the hydrophilic coating layer may not be smooth, and peeling of the hydrophilic coating layer may occur frequently. In addition, when the wettability improving material is included in excess of 100,000 parts by weight, the degree of wettability improvement may be insignificant, and the concentration of the polyvinyl alcohol and the crosslinking agent provided in the hydrophilic coating layer forming composition may be low, so that the formation of the hydrophilic coating layer may not be smooth.

Meanwhile, a hydrophilic coating layer may be formed by pre-treating the wettability improving agent on the nanofiber web, without treating the hydrophilic coating layer forming composition with a wettability improving agent. However, when the nanofibrous web in which the wettability improving agent is carried in the pores is immersed in the hydrophilic coating layer forming composition, the wettability improving agent carried in the pores exits the nanofiber web, and at the same time, the time required for the hydrophilic coating layer forming composition to penetrate the pores This lengthens the manufacturing time. In addition, as the degree of penetration of the hydrophilic coating layer forming composition differs depending on the thickness of the nanofiber web and the diameter of the pores, the hydrophilic coating layer may be formed non-uniformly for each position of the fiber web. Furthermore, as the hydrophilic coating layer is formed non-uniformly, pores may be closed with the hydrophilic coating layer in a part of the nanofiber web, and in this case, the desired flow rate may not be obtained as the pore structure of the initially designed nanofiber web changes. Equipped with a wettability improving agent in the hydrophilic coating layer forming composition is advantageous to simultaneously reduce the manufacturing time, simplify the manufacturing process and improve the formation of the hydrophilic coating layer without changing the pore structure of the nanofiber web.

The above-described method for forming the hydrophilic coating layer forming composition on the nanofiber web can be employed without limitation in the case of a known coating method, and for example, dipping, spraying, or the like can be used.

Thereafter, a step of forming a hydrophilic coating layer by heat-treating the composition for forming a hydrophilic coating layer treated on the nanofiber web may be performed. Through the heat treatment, the drying process of the solvent in the hydrophilic coating layer forming composition may be simultaneously performed. The heat treatment may be performed in a dryer, wherein the heat applied may be 80 to 160°C, and the treatment time may be 1 minute to 60 minutes, but is not limited thereto.

Next, as a step (2) according to the present invention, the laminating is performed by arranging the laminated nanofiber web and the second support on both sides of the first support so that the second support contacts the first support.

The step (2) comprises 2-1) laminating the second support and the nanofibrous web laminated in step (1) described above on both sides of the first support; And 2-2) fusing the first support and the second support by applying any one or more of heat and pressure.

As a specific method of applying heat and/or pressure in step 2-2), a known method may be adopted, and as a non-limiting example, a conventional calendering process may be used, and the temperature of the heat applied at this time is 70 It may be ~ 190 ℃. In addition, when performing the calendering process, it may be divided into several steps and carried out multiple times, for example, after the first calendering, the second calendering may be performed. At this time, the degree of heat and/or pressure applied in each calendering process may be the same or different. Through the step 2-2), binding through heat fusion may occur between the second support body and the first support body, and there is an advantage of omitting a separate adhesive or adhesive layer.

The present invention includes a filter unit implemented by including a filter medium prepared through the above-described manufacturing method.

6A, the filter media 1000 may be implemented as a flat filter unit 2000. Specifically, the flat filter unit 2000 includes a filter medium 1000 and a support frame 1100 supporting the rim of the filter medium 1000, and any one area of the support frame 1100 includes a filter medium A suction port 1110 that can gradient a pressure difference between the outside and the inside of the 1000 may be provided. In addition, the support frame 1100 so that the filtrate filtered from the nanofiber webs 101 and 102 can be discharged to the outside through the support 200 in which the second support/first support inside the filter medium 1000 is stacked. The flow path can be formed.

Specifically, in the filter unit 2000 as shown in FIG. 6A, when a high pressure suction force is applied through the suction port 1110, the filter medium (P) disposed outside the filter medium 1000 as shown in FIG. ), the filtrate (Q1) filtered through the nanofiber webs 101 and 102 flows along the flow path formed through the support body 200 on which the second support/first support is stacked, and then the support frame 1100 It is introduced into the flow path (E) provided in, the introduced filtrate (Q2) may be discharged to the outside through the suction port 1110.

In addition, the flat filter unit 2000 as shown in FIG. 6A can implement a filter module provided with a plurality of spaced apart predetermined spaces in one outer case, and such a large number of filter modules are stacked/blocked again. A water treatment device can also be configured.

The present invention will be described in more detail through the following examples, but the following examples are not intended to limit the scope of the present invention, which should be interpreted to help understand the present invention.

<Preparation example: Hydrophilic coating layer formation composition>

After mixing 7142 parts by weight of ultrapure water with respect to 100 parts by weight of polyvinyl alcohol (Kuraray, PVA217) as a hydrophilic component, a mixed solution was prepared by dissolving PVA using a magnetic bar at a temperature of 80° C. for 6 hours. Subsequently, the mixture solution was lowered to room temperature, and then, as a crosslinking agent, polyacrylic acid comaleic acid (Aldrich, PAM) was mixed with the mixture solution to 15 parts by weight based on 100 parts by weight of polyvinyl alcohol and dissolved at room temperature for 12 hours. Then, 7142 parts by weight of isopropyl alcohol (Ducsan Chemical, IPA) was added to the mixed solution with respect to 100 parts by weight of the polyvinyl alcohol and mixed for 2 hours to prepare a composition for forming a hydrophilic coating layer.

<Example 1>

First, in order to prepare a spinning solution, 12 g of polyvinylidene fluoride (Arkema, Kynar761) as a fiber-forming component was mixed with 88 g of a mixed solvent of dimethyl acetamide and acetone at 70:30 at 88 g for 6 hours at a temperature of 80°C. While dissolving using a magnetic bar to prepare a mixed solution. The spinning solution was introduced into the solution tank of the electrospinning apparatus, and discharged at a rate of 15 μl/min/hole. At this time, while discharging the spinning solution while applying air in the same direction as the spinning direction of the spinning nozzle, the temperature of the spinning section was maintained at 30°C, and the humidity was 50%, the distance between the collector and the spinning nozzle tip was 20 cm, and the collector A low-melting composite fiber with an average thickness of 200 µm and a basis weight of 40 g/m 2, with a melting point of about 120° C. as the first part, and a polypropylene-based fiber with an average diameter of 15 µm as the second support. After placing the formed nonwoven fabric (Namyang Nonwoven Fabric, CCP40), apply a voltage of 40 kV or more to the Spin Nozzle Pack using a high voltage generator, and at the same time, apply an air pressure of 0.03 MPa per nozzle to the second support. A laminate having a nanofiber web formed of PVDF nanofibers having an average fiber diameter of 0.5 µm was prepared on one side of the fabric. Next, the solvent and moisture remaining on the nanofiber web of the layered product were dried, and heat and pressure were applied at a temperature of 140° C. or higher and 1 kgf/cm 2 to heat-seal the second support body and the nanofiber web to perform a calendering process. . The prepared laminate had a shape as shown in FIG. 5, and the second support body and the nanofiber web were thermally fused and bound, and the nanofiber web had a three-dimensional network structure in the shape as shown in FIGS. 4A and 4B. At this time, the average pore diameter of the nanofiber web was 300 nm, the porosity was 80%, the average thickness was 20 μm, and the basis weight was 10 g/m 2. In addition, the tensile strength in the MD direction of the nanofiber web was 4 kg/mm 2, and the tensile strength in the TD direction was 2.5 kg/mm 2.

Thereafter, the prepared laminate was immersed in the composition for forming a hydrophilic coating layer prepared in the preparation example, and then dried at a temperature of 110° C. for 5 minutes in a dryer to provide a hydrophilic coating layer on the nanofiber surface of the nanofiber web.

Subsequently, the laminate was placed on both sides of the first support so that the second support faced the manufactured laminate. At this time, the first support was formed of a low melting point composite fiber having an average thickness of 35 mm and an average thickness of 4 mm and a basis weight of 500 g/m2, polyethylene having a melting point of about 120°C, and polypropylene as the core. Non-woven fabric (Namyang non-woven fabric, NP450) was used. After that, a filter medium was prepared by applying heat and a pressure of 1 kgf/cm 2 to a temperature of 140° C. or higher.

<Examples 2 to 11 and Comparative Example 1>

Prepared in the same manner as in Example 1, the tensile strength in the MD direction of the nanofiber web, and the tensile strength and porosity in the TD direction were changed to prepare filter media as shown in Tables 1 and 2.

<Experimental Example 1>

The following physical properties were evaluated for each filter media prepared according to Examples and Comparative Examples and are shown in Tables 1 and 2.

1. Standard deviation and average tensile strength of tensile strength in MD direction

For the nanofibrous webs provided in each filter media prepared according to the above Examples and Comparative Examples, the nanofiber webs were cut into horizontal x vertical 250mm x 150mm sizes, and each nanofiber web was divided into 10 equal parts in the MD direction. The tensile strength of the central portion of the formed first region to the tenth region was measured, and the average value thereof was calculated to measure the average tensile strength in the MD direction, and in the tensile strength values of the central portions of each of the first region to the tenth region, After calculating and squaring each'deviation' value minus the average tensile strength of the measured MD direction, calculating the'dispersion' by measuring their average value, and applying the square root to the variance value, the standard deviation of the tensile strength in the MD direction Was measured. At this time, the tensile strength was measured through a tensile strength tester (HZ-1007E, MMS) at a rate of 20 mm/min at a temperature of 25°C.

2. Standard deviation and average tensile strength of tensile strength in TD direction

With respect to the nanofiber web provided in each filter media prepared according to the above Examples and Comparative Examples, the nanofiber web is cut into a size of 150 mm x 250 mm in width x length, and each nano fiber web is divided into 10 equal parts in the TD direction. The tensile strengths of the central portions of the formed first to tenth regions were measured, and the average values thereof were calculated to measure the average tensile strength in the TD direction. From the values of the tensile strengths of the central portions of each of the first to tenth regions, After calculating and squaring each'deviation' value by subtracting the measured average tensile strength in the TD direction, calculate the'dispersion' by measuring their average value, and apply the square root to the variance value to standard deviation of the tensile strength in the TD direction Was measured. At this time, the tensile strength was measured through a tensile strength tester (HZ-1007E, MMS) at a rate of 20 mm/min at a temperature of 25°C.

<Experimental Example 2>

The following physical properties were evaluated for each filter media prepared according to Examples and Comparative Examples and are shown in Tables 1 and 2.

1. Relative Water permeability Measure

For the filter unit implemented with each filter medium prepared in Examples and Comparative Examples, the water permeability per 0.5 m 2 of the specimen area was measured by applying an operating pressure of 50 kPa, and the water permeability of the filter medium of Example 1 was set to 100. As a reference, the water permeability of the filter media according to the remaining examples and comparative examples was measured.

2. Filtration efficiency evaluation

For the filter unit implemented with each filter media prepared in Examples and Comparative Examples, turbidity before and after filtration was prepared by dispersing test dust (ISO Test dust A2 fine grades) in pure water to prepare a turbid solution having a turbidity of 100 NTU. Filtration efficiency through measurement was measured.

3. Water treatment Durability evaluation

For any filter unit implemented with each filter media prepared in Examples and Comparative Examples, when no abnormality occurs when measuring water permeability and evaluating filtration efficiency-○, damage of nanofibers, trimming, of nanofiber web When any problem such as deformation occurs, the durability of water treatment was evaluated as -×.

4. Backwash Durability evaluation

For the filter unit implemented with each filter media prepared in Examples and Comparative Examples, backwashing was performed under conditions of pressing 400LMH of water for 2 minutes per 0.5 m 2 of the specimen area by immersing in water and applying an operating pressure of 50 kPa. After that, when no abnormality occurred-○, when any problems such as swelling of the separation membrane and interlayer peeling occurred, the backwash durability was evaluated as x.

division Example
One Example
2 Example
3 Example
4 Example
5 Example
6 Nano
Textile web Tensile strength in the TD direction (kg/㎟) 2 6 3 1.3 0.2 0.5 Tensile strength in MD direction (kg/㎟) 5 6.6 4.5 6.5 1.6 2 TD:MD 1:2.5 1:1.1 1:1.5 1:5 1:8 1:4 Porosity (%) 75 44 77 81 88 84 MD
direction Standard deviation of tensile strength
(kg/㎟, σ _MD ) 0.1 0.22 0.16 0.2 0.1 0.1 Average tensile strength
(kg/㎟, A _MD ) 5 6.6 4 6.5 1.6 2 Equation
One σ _MD /A _MD 0.02 0.033 0.04 0.031 0.063 0.05 TD
direction Standard deviation of tensile strength
(kg/㎟, σ _TD ) 0.08 0.24 0.08 0.03 0.015 0.025 Average tensile strength
(kg/㎟, A _TD ) 2 6 2 1.3 0.2 0.5 Equation
2 σ _TD /A _TD 0.035 0.04 0.04 0.023 0.075 0.05 filter
unit Relative water permeability (%) 100 55 99 102 - 105 Filtration efficiency (%) 97 98 97 94 - 89 Water treatment durability ○ ○ ○ ○ × ○ Backwash durability ○ × ○ ○ × ○

division Example
7 Example
8 Example
9 Example
10 Example
11 Comparative example
One Nano
Textile web Tensile strength in the TD direction (kg/㎟) 4 0.4 0.6 3 2 4 Tensile strength in MD direction (kg/㎟) 6 0.6 One 8 5 0.9 TD:MD 1:1.5 1:1.5 1:1.67 1:2.67 1:2.5 1:0.23 Porosity (%) 67 89 85 51 36 83 MD
direction Standard deviation of tensile strength
(kg/㎟, σ _MD ) 0.21 0.012 0.05 0.3 0.7 0.03 Average tensile strength
(kg/㎟, A _MD ) 6 0.6 One 8 5 0.9 Equation
One σ _MD /A _MD 0.035 0.02 0.05 0.038 0.14 0.033 TD
direction Standard deviation of tensile strength
(kg/㎟, σ _TD ) 0.17 0.01 0.03 0.08 0.3 0.1 Average tensile strength
(kg/㎟, A _TD ) 4 0.4 0.6 3 2 4 Equation
2 σ _TD /A _TD 0.043 0.025 0.05 0.027 0.15 0.025 filter
unit Relative water permeability (%) 87 - 103 72 117 98 Filtration efficiency (%) 98 - 91 98 69 96 Water treatment durability ○ × ○ ○ ○ ○ Backwash durability ○ × ○ × ○ ×

As can be seen from Table 1 and Table 2, according to the present invention, the tensile strength in the MD direction of the nanofiber web, the tensile strength in the TD direction, porosity, the implementation of satisfying the ranges of Equations 1 and 2, etc. Examples 1, 3, 4, 6, 7 and 9 have relative water permeability, filtration efficiency, water treatment durability, and backwash durability compared to Examples 2, 5, 8, 10, 11 and Comparative Example 1 in which any of them is missing. It was found that all of these were remarkably excellent at the same time.

In particular, Example 5 and Example 8, as the water treatment durability is significantly reduced, it was impossible to measure the water permeability and filtration efficiency.

Although one embodiment of the present invention has been described above, the spirit of the present invention is not limited to the embodiments presented herein, and those skilled in the art to understand the spirit of the present invention may add elements within the scope of the same spirit. However, other embodiments may be easily proposed by changing, deleting, adding, or the like, but it will also be considered to be within the scope of the present invention.

101,102,111,112: Nano fiber web
111a: nanofiber
121,122: second support
121a: Second composite fiber
130: first support
130a: first composite fiber
1000: filter media
2000, 2000': Filter unit

Claims (16)

A porous first support;
Stacked on each of the upper and lower portions of the first support, the tensile strength in the direction of MD (Mechanical Direction) is 0.8 to 7.0 kg/㎟ and the tensile strength in the direction of TD (Transverse Direction) is 0.3 to 5.0 kg/㎟, and TD ( A nanofiber web in which the ratio of tensile strength in the transverse direction) and tensile strength in the MD (mechanical direction) direction is 1: 1.2 to 6.5, and the values of the following equations 1 and 2 are 0.1 or less, respectively; And
A filter medium comprising; a porous second support interposed between the first support and the nanofiber web;
[Equation 1]
(Standard deviation of tensile strength in MD direction) / (Average tensile strength in MD direction)
[Equation 2]
(Standard deviation of tensile strength in the TD direction) / (Average tensile strength in the TD direction) delete delete delete delete According to claim 1,
The average fiber diameter of the nanofibers is 0.05 ~ 1㎛ filter media. According to claim 1,
The filter media having an average pore size of 100 to 5000 nm in the nanofiber web. According to claim 1,
The nanofiber web is a filter medium having a porosity of 50 to 90%, a basis weight of 0.05 to 20 g/m 2 and a thickness of 0.5 to 200 μm. According to claim 1,
The first support member and the second support member are each independently a filter media of any one or more selected from the group consisting of non-woven fabric, fabric and knitted fabric. According to claim 1,
The first support has a basis weight of 250 to 800 g/m 2, and a thickness of 2 to 8 mm,
The second support has a filter medium having a basis weight of 35 to 100 g/m 2 and a thickness of 100 to 400 μm. According to claim 1,
The second support includes a second composite fiber disposed to expose at least a portion of the low-melting component, including a supporting component and a low-melting component, to the outer surface, and the low-melting component of the second composite fiber is a nanofiber web Filter media fused to The method of claim 11,
The first support includes a first composite fiber disposed to expose at least a portion of the low-melting component, including a supporting component and a low-melting component, to the outer surface, and a low-melting component and a second composite of the first composite fiber A filter medium in which the first support and the second support are joined by fusion between the low-melting component of the fiber. According to claim 1,
The average fiber diameter of the first support is 5 ~ 50㎛,
The filter media having an average fiber diameter of 5 to 30㎛ of the second support. (1) laminating a nanofiber web and a second support; And
(2) placing and laminating the laminated nanofiber web and the second support on both sides of the first support so that the second support is in contact with the first support;
The nanofiber web has a tensile strength in the MD (Mechanical Direction) direction of 0.8 to 7.0 kg/㎟ and a tensile strength in the TD (Transverse Direction) direction of 0.3 to 5.0 kg/㎟, a tensile strength in the TD (Transverse Direction) direction, and Method of manufacturing a filter medium, wherein the ratio of the tensile strength in the direction of MD (Mechanical Direction) is 1: 1.2 to 6.5, and the values of the following Equations 1 and 2 are 0.1 or less, respectively:
[Equation 1]
(Standard deviation of tensile strength in MD direction) / (Average tensile strength in MD direction)
[Equation 2]
(Standard deviation of the tensile strength in the TD direction) / (Average tensile strength in the TD direction) The method of claim 14,
The step (1) is a method of manufacturing a filter medium for laminating the nanofiber web and the second supporter by electrospinning nanofibers on one surface of the second supporter and then applying at least one of heat and pressure. The filter medium according to any one of claims 1, 6 to 13; And
A flat filter unit comprising a; and a support frame for supporting the rim of the filter medium, and having a flow path to allow the filtrate filtered from the filter medium to flow out.

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