JP5946894B2 - Filter using nanofiber - Google Patents

Description

  The present invention relates to a filter using nanofibers, and more particularly to a filter that exhibits performance efficiently and improves strength using nanofibers.

Recently, nanofibers, which are generally defined as fibers having a diameter of 1 micron (= 1,000 nm) or less, have been developed. As a method for producing nanofibers, an ESD (Electro-Spray Deposition) method, Alternatively, a technique called electrospinning method has received the most attention, and the technique has been developed (see, for example, Patent Document 1, Patent Document 2, and Patent Document 3).
In the production of nanofibers by this ESD method, first, a syringe is filled with a solution of various biopolymers or polymers (hereinafter sometimes simply referred to as “polymers”) dissolved or melted in a solvent. A strong electric field is applied between the needle electrode and the collector electrode by applying a DC high voltage of several kV to several tens of kV from the high voltage DC power source between the needle electrode and the collector electrode on which the nanofibers are deposited. Generate a field.
In this environment, when the spinning solution is discharged from the needle-type electrode toward the collector electrode, the solvent that dissolved the polymer evaporates instantaneously in the electric field, and the polymer stretches with Coulomb force while solidifying. Then, nano-order fibers are formed under mild conditions at room temperature and atmospheric pressure.

Nanofibers can be expected to exhibit unique functions due to nanostructures. For example, nanofibers have a surface area in the same volume that is much larger than that of normal fibers. In addition, new functions such as adsorption properties and adhesive properties are developed, and development of new materials that are not possible in the past can be expected. Research on multifunctional special protective clothing worn by police officers, firefighters, doctors, and nurses has begun, and military applications are military uniforms that are lighter than before and have functions that have never existed, gathering in nanometer units. Development of new laminated materials with different functions is progressing. Furthermore, as shown in Patent Document 4, since the filter made of nanofibers can increase the space for a small area occupied by the fibers, it can be expected to have a high collection efficiency with low pressure loss. Air filters, masks, etc. have been developed, and ultra-lightweight, high-functional protective clothing for biochemical hazard protection using nanofibers and regenerative medicine using nanofibers as a medium are being actively developed.
In addition, it is transparent to visible light, the pore size can be controlled in the nano order, advanced molecular organization is possible, and the living body does not feel nanofiber as a foreign substance and has good biocompatibility. It is done.

  However, the nanofiber manufacturing method or apparatus by the ESD method has a drawback that it is not suitable for mass production because the amount of spray from one nozzle is very small. In the ESD method, although it varies depending on the compound and spray conditions, the spray speed from one nozzle is usually about several μρ per minute. Therefore, when mass production is performed, a large number of nozzles are arranged, A method of electrostatic spraying from a nozzle is employed. The manufacturing method of the ESD nanofiber using such a large number of nozzles requires a large number of nozzles, so that the quality is insufficient, maintenance is difficult, and the manufacturing cost is high. It was.

JP2002-249966 JP 2004-68161 A JP 2008-274487 A JP 2006-289209 A Japanese Patent Application No. 2010-258324

As described above, filters using nanofibers have also been developed in the past. However, nanofibers are expensive and there are problems in fixing nanofibers because they are held between substrates. There were problems such as inconvenience and not being popularized.
An object of the present invention is to provide a filter having a high collection rate using nanofibers and a low pressure loss and having a high strength.
And unlike the conventional filter using conventional nanofibers, the nanofibers are not displaced with time, and the strength of the substrate is different. It is to provide a filter using nanofibers that is the same as that of the filter using nanofibers and has a function of having a high collection rate and low pressure loss, which are characteristics of the filter using nanofibers, as much as possible.

In order to solve the above-mentioned problems, the invention of claim 1 is directed to a non-woven fabric base material having a coarser mesh than the produced filter and a nanofiber material having a diameter of 100 nm to 50 nm having a uniform thickness. A filter in which an EVA hot melt adhesive having a nanofiber diameter of 200 nm to 400 nm is disposed between the fiber layer and the adhesive is disposed on the substrate in a zigzag manner. A filter using nanofibers, wherein the base material and the nanofiber layer are bonded so that the nanofibers to be formed are not covered with a film.
The invention according to claim 2 is the filter using the nanofiber according to claim 1, wherein the basis weight of the nanofiber of the filter is 0.0004 g / cm ² .
The invention according to claim 3 is the filter using the nanofiber according to claim 1 or 2, wherein the basis weight of the nonwoven fabric as a base material is 0.007 g / cm ² .

According to the present invention, since the adhesive is integrated at a predetermined temperature and pressure so as to prevent the nanofiber's eyes from becoming clogged, the nanofiber is used for bonding the substrate and the nanofiber. It has a high collection rate and low pressure loss, and is a filter using strong nanofibers.
This is different from the conventional filter using nanofibers, in which the nanofibers are simply sandwiched between the substrates, and the position of the nanofibers does not shift over time, and the strength of the substrate It becomes the filter using the nanofiber in a state where the function having the high collection rate and the low pressure loss which are the characteristics of the filter using the nanofiber is not impaired as much as possible.

The conceptual schematic diagram of the manufacturing method of the filter using the nanofiber of the embodiment of the present invention, Explanatory drawing which shows the electric lines of force of the metal ball of the present invention and the spinning nozzle, 3 (a) is an explanatory view showing the relationship between the metal sphere, the high-speed air current injection nozzle, and the spinning nozzle in FIG. 1, FIG. 3 (b) is an explanatory view from the side of FIG. 3 (a), An explanatory view of a single nanofiber manufacturing apparatus in which a plurality of metal spheres and the spinning nozzle units are arranged in a nanofiber generation unit, Figure in [Table 1] of the relationship between the distance C between the high-speed airflow injection nozzle and the spinning nozzle and the nanofiber generation state. Figure [Table 2] of the relationship between the axis D of the spinning nozzle and the metal sphere, the distance D between the high-speed air current jet nozzle and the nanofiber generation state. Figure [Table 3] shows the relationship between the distance B between electrodes and the voltage and the state of nanofiber formation depending on the size of the metal sphere (electrode). A schematic cross-sectional view of a nozzle part for jetting an adhesive; The expanded sectional view of the front-end | tip of the nozzle part of FIG. A diagram of a microphotograph at 1000 magnifications of a polyethersulfone (PES) nanofiber and an adhesive (EVA) produced when the heating roller of Example 1 was set to 70 ° C., A diagram of a microphotograph at 1000 magnifications of a polyethersulfone (PES) nanofiber and an adhesive (EVA) produced when the heating roller of Example 1 was set to 71 ° C., It is the figure of the microphotograph of 1000 magnifications of the nanofiber of the polyethersulfone (PES) manufactured when the heating roller of Example 1 was 75 degreeC, and the adhesive agent (EVA).

The feature of the present invention is that the nanofiber generating unit is made smaller and a plurality of necessary nanofiber filter layers are formed, and at the same time, they are adhered to a strong substrate, and the form of adhesion does not deteriorate the filter function. It is what I did.
Hereinafter, preferred embodiments of a filter using the nanofiber of the present invention and a method for producing the same will be described with reference to the drawings.

The filter using the nanofiber of Example 1 of the present invention and the manufacturing method thereof will be described. Basically, as shown in the conceptual explanatory diagram showing the outline of FIG. 1, ESD (Electro-Spray Deposition) and The jet ESD method combined with a high-speed jet stream (jet) is adopted, and the nanofiber generating part J, the nanofiber adhesive generating part K, the nanofiber collecting part L1, and the collecting part L of the filter forming part L2 It is composed of
[Nanofiber generation part J]
Examples of the polymer material having a long molecular arrangement of the present invention include biopolymer solutions such as proteins, organic polymer solutions, polymer solutions, and the like, but the nanofiber production apparatus (production method) of Example 1 is highly expensive. Polyethersulfone (PES) is used as the molecular material.
The reason why the polyethersulfone (PES) is used as a material of the filter is that, in addition to excellent heat resistance, a thinner nanofiber of 100 nm to 50 nm can be produced by the production apparatus disclosed in the present invention. .
The material supply unit 1 in FIG. 1 contains a polymer solution N1 obtained by dissolving polyether sulfone (PES) as a material with DMF (dimethylformamide) as an organic solvent.
The polymer solution N1 in the material supply unit 1 is subjected to extrusion pressure by the gear pump 11. The polymer solution N1 is supplied by the gear pump 11 capable of accurately delivering a predetermined amount through the supply pipe 12 so as to push out the predetermined amount to the spinning nozzle 21. The polymer solution N1 is introduced into the metal spinning nozzle portion 2 through the supply pipe 12, and is spun into the spinning nozzle portion 2 from the opening 211 at the tip of the spinning nozzle 21. Here, by appropriately adjusting the above-described gear pump 11 that adjusts the speed at which the polymer solution N1 is spun, appropriate discharge is performed so that nanofibers are uniformly generated from the plurality of spinning nozzles 21 as described later. Adjust to speed.

By the way, the principle of the ESD method is that a polymer material having a long molecular arrangement such as polyethersulfone (PES) is swollen with a flammable organic solvent and exists in a disperse state. When released, the solvent rapidly evaporates due to the large surface area, shrinks laterally, and aligns in the longitudinal direction of the polymer molecular chain. Then, the polymer elongates due to the evaporation of the solvent and the accompanying increase in the Coulomb force. By repeating this, it gradually grows and grows into nanofibers. It is considered that the polymers that were disjointed as the polymers stretched are aligned while being intertwined. In the case where the material is a low molecule, the length of the molecule itself is short, so that the nano particles are generated without being entangled.
Therefore, by adjusting the discharge speed of the polymer solution N1, it is possible to obtain a dry deposit instead of a wet deposit formed at an excessive speed. That is, it is necessary to adjust the discharge speed to a limit that does not cause wet deposits.

In FIG. 1, a metal part metal ball 31 that forms a spherical electrode part 3 is disposed in the generation unit device frame M so as to face the opening direction of the spinning nozzle 21 and the opening 211 of the spinning nozzle. 211 and the shortest surface distance of the metal sphere 31 are installed at a predetermined interval.
The spinning nozzle 21 is also made of a conductive metal, and a high voltage power source 33 is applied to the spinning nozzle 21 and the metal ball 31, and a negative voltage of the high voltage power source 33 is applied to the metal ball 31. It is supplied via a lead wire, and the plus side is grounded G via the lead wire.
By applying a high voltage from the high voltage power source 33, a positive voltage is applied to the polymer solution N1 via the spinning nozzle 21, and the polymer in the polymer solution N1 to be spun is charged positively. The Note that the plus and minus are not limited to those in the first embodiment, and it is sufficient that a charge is applied to the polymer material. Conversely, the polarity of the voltage applied to the polymer solution N1 may be minus. .
In addition, the metal guide tube 22 up to the spinning nozzle 21 of the spinning nozzle unit 2 is heated by a heater 23 such as a heater to reduce the viscosity of the polyethersulfone (PES) as much as possible. Is heated to about 80 ° C.

The reason why the positive electrode is the metal ball 31 is that, as shown in FIG. 2, the electric lines of force E are concentrated to the maximum at the opening 211 at the tip of the spinning nozzle 21. The polymer material N1 inside jumps out linearly toward the metal sphere 31. Therefore, the diameter of the metal sphere 31 may be set such that the electric field lines E are most efficiently concentrated on the spinning nozzle 21. In the prior art, the diameter of the sphere is assumed to be 25 mm assuming that a charged state is generated. The high voltage was 30 Kv, but the distance between the spinning nozzle 21 and the metal sphere 31 was 55 mm to 65 mm so as not to discharge, although the optimum value varied depending on the voltage of the high voltage power source. By the way, if the diameter of the metal sphere is too small and it is made to be a needle, a discharge occurs and short-circuits, and the spinning nozzle 21 and the metal sphere 31 are not charged.
Further, the high-speed airflow injection nozzle portion 4 positioned between the spinning nozzle 21 and the metal ball 31 needs to be made of a synthetic resin made of an insulating material instead of metal so as not to be charged.

Here, the charged nanofibers are electrostatically induced while floating from the spinning nozzle 21, and the amount of + charges in the opening 211 of the spinning nozzle 21 is neutralized. In this case, it will float as a droplet, but the course of the nanofiber to be spun is changed by a high-speed air jet nozzle 41 (see FIG. 1), which will be described later, between the spinning nozzle 21 and the metal ball 31. By removing from this, both can still keep the capacitor coupling and the production can be increased, which is also one of the important features of the present invention.
In this embodiment, the metal ball 31 and the spinning nozzle 21 are applied by the high voltage power source 33 and the spinning nozzle 21 is set to the ground G. Therefore, the spinning nozzle 21 (ground G) is applied by applying the metal ball 31. ) Is electrostatically induced, and the charge is supplied to the polymer of the nanofiber. Basically, the metal sphere 31 is merely electrostatically induced, and the current is supplied from the ground side to consume power. Is zero. This is also one of the important features of the present invention, and even if the number of spinning nozzles 21 is sufficiently increased and arranged in parallel, a small high-voltage power supply is sufficient. Therefore, the production units Y of the metal spheres 31 and the high-speed air jet nozzles 41 can be reduced in size, and the production units Y per unit area can be concentrated to greatly increase the production amount.

Next, a high-speed air flow injection nozzle portion 4 that discharges a high-speed air flow is arranged in the path between the metal ball 31 and the spinning nozzle opening 211 so as to be orthogonal to each other. The high-speed airflow X generated by the high-pressure pump 42 from the injection nozzle 41 of the high-speed airflow injection nozzle section 4 generates a low pressure at the spinning nozzle opening 211 and generates a force for sucking up the polymer solution N1 from the opening 211. . Therefore, the high-speed airflow X needs to be on a line (path) connecting the metal ball 31 and the spinning nozzle opening 211.
Therefore, in this embodiment, as shown in FIG. 3B, a plurality of openings 411 (three in FIG. 1) of the jet nozzle 41 for high-speed airflow are provided horizontally, and the airflow layer has a predetermined width in the horizontal direction. Therefore, the high-speed airflow X can be easily located on the line (path) connecting the metal ball 31 and the spinning nozzle opening 211.

The high-speed airflow X is air dried to a humidity of 30% or less by a dryer in this embodiment, and the temperature is kept constant so that the state of the nanofiber is kept constant, and the wind speed is 200 m / By setting the aspect ratio of the nanofiber to a large value for sec or more, the evaporation of the solvent is promoted, and as a result, the polymer material is cured, but it is maximized until it cannot be stretched by Coulomb force until it is cured. It will be.
Therefore, the distance from the nozzle opening 211 to the collection surface of the nanofiber collection part L1 also needs to be a distance for the nanofiber to extend to the nano unit. In Example 1, it depends on the temperature in the apparatus. However, the distance is about 1 m or more. Actually, this distance is set to 4 m or more to make the stacking state uniform on the collecting surface. By increasing the distance, air is sucked from the back surface of the base material, and the suction force is increased at a rough spot. This makes it possible to laminate the nanofibers more uniformly than the nanofibers are attracted to the location.
In addition, one of the important features of the present invention is that the charge is generated at a low pressure generated in the vicinity of the opening 211 by the Coulomb force from the metal sphere 31 and the opening 411 of the high-speed airflow injection nozzle portion 4 and the injection nozzle 41. It is to give a high-speed air flow of 200 m / sec or more that is dried at a constant temperature necessary for the production of nanofibers by linearly ejecting the polymer.

Here, the arrangement of the openings 411 of the jet nozzle 41 for high-speed airflow will be described with reference to [Table 1] in FIGS. 3 and 5 and [Table 2] in FIG.
The distance C (C in FIG. 3) from the line B connecting the spinning nozzle 21 and the metal ball 31 to the opening 411 of the injection nozzle 41 is as shown in [Table 1] in FIG. Regardless of the diameter, nanofiber generation is “good” and optimal at a position C about 3 mm to 4 mm away from the line at right angles, but this is not a fiber but a droplet at a distance of 3 mm or less. This is because, if the distance is greater than this, a phenomenon such that the ink is sucked back to the jetting nozzle part 4 side and returns to the collecting part L, and does not scatter to the collecting part L and adheres to the metal ball 31. It should be noted that the speed of the air sprayed from the opening 411 of the spray nozzle 41 is rapidly decelerated even at a position of 3 mm, so that even if the speed is significantly increased to 200 m / sec or more, the effect is weak.

Next, the distance D from the injection nozzle opening 411 of the high-speed airflow injection nozzle section 4 is horizontal from the linear spinning nozzle opening 211 regardless of the diameter of the metal ball 31 as shown in [Table 2] in FIG. The generation of nanofibers is good with a distance (distance D) of 8.5 mm to 10 mm, which is “good” and optimal. However, when the distance is 6.5 mm or less, the fibers do not become fibers but become droplets. It is because it will return, and even if it leaves | separates more than this, it will become a droplet.
In summary, the opening 411 of the high-speed air flow injection nozzle has a horizontal distance (distance D) from the spinning nozzle opening 211 of 8.5 mm to 10 mm, and the opening 411 includes the bottom surface 311 of the metal ball 31 and the spinning nozzle. It can be seen that it is parallel to the line B connecting the openings 211 and is 3 mm to 4 mm away from the spinning nozzle opening 211 by a vertical distance (distance C). In addition, although the manufacturing method of this nanofiber is one nanofiber irrespective of the quantity produced | generated from the one spinning nozzle 21, when it is transferred by high-speed air, By the random traversing action, it is accumulated on the collecting surface in a nonwoven fabric shape.

Here, in order to produce a large amount of nanofibers, as shown in FIG. 4, a plurality of the spinning nozzles 21 shown in FIG. However, the problem is that if the distance B between the spinning nozzle 21 in the opening 411 of the injection nozzle 41 and the metal ball 31 is large, the apparatus becomes large, and the injection nozzle 41 and the spinning nozzle As the distance between the unit Y of the jet nozzle 41 of 21 and the high-speed airflow and the adjacent unit Y increases, the non-woven fabric at the collecting portion L is spotted.
In order to avoid this, it is necessary to make the distance B as short as possible on condition that the production of nanofibers is “good”.
In the apparatus of this embodiment, the unit Y is 6 units Y horizontally, 4 units Y vertically parallel, and the top horizontal is 6 units Y + 1 unit Y, so a total of 6 × 4 + 1 = 25 units are arranged. doing. (Figure 4 shows part of it)

One of the features of the present invention is that if the diameter of the metal sphere 31 is reduced on the condition that nanofibers are generated, the distance B (FIG. 3) between the bottom surface 311 of the metal sphere 31 and the spinning nozzle opening 211 is increased. This is based on the discovery that it can be reduced and that the voltage of the high voltage also decreases.
However, if the diameter of the metal sphere 31 is made too small and close to a needle shape, the vicinity of (1) is not charged, but a short circuit due to discharge occurs, and the charged atmosphere as shown in FIG. It was found that nanofibers were not generated, and (2) droplets or liquid particles were formed, and in this case, nanofibers were not generated.

This is verified in the experiment in [Table 3] in FIG.
In [Table 3], the diameter A of the metal sphere 31 in FIG. 3 is prepared as 25 mm, 15 mm, 10 mm, 8 mm, 6 mm, 5 mm, 4 mm, and 1 mm, and the bottom surface 311 of the metal sphere 31 is provided for each metal sphere 31. The distance B between the nozzle opening 211 and the spinning nozzle opening 211 is 11.5 mm, 16.5 mm, 22 mm, 28 mm, 35 mm, and the prior art 55 mm to 65 mm. 13 kv, 18 kv, and 23 kv were applied to each to verify the state of nanofiber formation. In addition, this was repeated five times, and the nanofiber production state was determined as “◎” indicating that the spinning material was produced on the nanofiber, and “good” indicating that the nanofiber was capable of being produced. “A” indicates that the spinning material is not a fiber but a droplet, “b” indicates that the material is not a droplet but it is finely crushed, and “c” indicates that the material is attached to a metal sphere. In addition, a state where the electric discharge is short-circuited due to discharge is represented by “d”, and a state where the state is returned to the high-speed airflow injection nozzle side without being scattered to the collecting portion is represented by “e”.

To explain this, the upper right column of [Table 3] is an example in the above-mentioned Patent Document 4, but the ball diameter was 25 mm and the voltage was 30 kv to 40 kv. The distance B between the bottom surface 311 of the metal sphere 31 and the spinning nozzle opening 211 was as large as 55 to 65 mm.
In this [Table 3], when the “possible” and “good” states in which nanofibers can be generated are surrounded by a thick dotted line, it can be seen that the region is indicated by the arrow Z in the lower left direction. This shows that when the diameter A of the metal sphere 31 is reduced, the distance B (FIG. 3) between the bottom surface 311 of the metal sphere 31 and the spinning nozzle opening 211 can be reduced, and the high voltage is also reduced. On the contrary, when the sphere diameter A is 1 mm or less, it is needle-like and discharge cannot be generated at a voltage of 13 kv, and when the voltage is 8 kv or less, droplets / liquid particles are formed and nanofibers are generated. It is not possible.

In [Table 3] in FIG. 7, the generation of nanofibers is good, the distance B is relatively short, and the voltage is relatively low. (1) When the diameter A of the metal sphere 31 is 6 mm, the distance B is (2) When the diameter A of the metal ball 31 is 5 mm, the distance B is 22 mm and the voltage is 13 kv, and the distance B is 16.5 mm and the voltage is 8 kv. ) When the diameter A of the metal sphere 31 is 4 mm, the distance B is 22 mm, and the voltage is 13 kv.
Including the case where it is not good and is “possible” (when discharge d occurs, it is in an unstable state and cannot be all), the diameter of the metal sphere 31 is changed from 8 mm to 4 mm, thereby making the metal sphere 31 And the spinning nozzle opening 211 can be 11.5 mm to 22 mm, and the high voltage can be 3 kv to 13 kv. Further, in consideration of the conditions under which the operation is stable, in order to include the case where the condition is “good”, the diameter of the metal ball 31 is changed from 6 mm to 4 mm, whereby the bottom surface 311 of the metal ball 31 and the spinning nozzle. The distance to the opening 211 can be 11.5 mm to 22 mm, and the high voltage can be 3 kv to 13 kv. However, when the distance between the bottom surface 311 of the metal sphere 31 and the spinning nozzle opening 211 is 11.5 mm, the diameter A of the metal sphere 31 is preferably 6 mm or 5 mm.
In this way, the diameter of the metal sphere 31 of the nanofiber generating part is reduced to a value just before the discharge (short-circuit) or just before the liquid droplet / liquid particle is not formed, within a range where the nanofiber can be stably generated. The generation unit Y is made smaller by reducing the distance B between the metal ball 31 and the spinning nozzle opening 211 and reducing the high voltage. This makes it possible to increase the number of spinning nozzle openings 211 per unit area, and as a result, it is possible to arrange a large number of generation units Y in parallel, producing a large amount of nanofibers and nonwoven fabrics thereof. be able to. As described above, in the apparatus of this embodiment, a total of 6 × 4 + 1 = 25 units are arranged.

[Conditions of Jet ESD Method of Example 1]
In Example 1 shown in FIG. 1, it can be seen from Table 3 that the diameter of the metal sphere is 5 mm under the condition that the nanofibers can be stably and satisfactorily formed. Therefore, the diameter A is 5 mm and the distance B is 16 mm. The voltage was set to 13 kv.
Setting conditions Material: Polyethersulfone (PES)
Solvent: DMF (dimethylformamide)
Fiber generator voltage: -13kv
High-speed air pressure: 0.4 MPa
Spinning amount (discharge amount): 0.5 mL / min
Diameter of metal sphere: 5mm
Distance between spinning nozzle and metal ball: 16mm
Distance from nozzle opening to collection surface: 3m
Absorption negative pressure at the collecting surface: 200Pa

In the experimental apparatus under the setting conditions in the above examples, nanofibers having a diameter of 50 nm to 100 nm can be produced. This is because the lower thin fibers in the electron micrographs shown in FIGS. Sulphone (PES) nanofiber.
Although only one nanofiber is spun from the spinning nozzle 21 in FIG. 1, the polyethersulfone (PES) nanofibers are in a non-woven fabric (web) form due to random traverse action or the like. You can see the state of lamination.
Note that substantially the same results were obtained with polyetherimide (PEI), polyurethane (PU), and polyvinylidene fluoride (PVDF) instead of polyethersulfone (PES) as the material in Example 1.

By the way, in Example 1, DMF (dimethylformamide) was used as a solvent for polyethersulfone (PES), but similar results can be obtained with other dimethylacetamide (DMAc).
Other polymer and solvent combinations include polyvinyl alcohol (PVA) and water, polyvinylidene fluoride (PVDF), polyacrylonitrile (PAN), and polyether sulfone (Polysulfone). Ether Sulphone, PES) and dimethylacetamide (DMAc) or DMF (dimethylformamide), nylon (Nylon) and formic acid, chitosan and acetic acid or citric acid and other weak acids, acrylic (polymethyl methacrylate, PMMA) and methanol, polylactic acid and chloroform Combinations and the like are possible for the production of nanofibers.

[Nanofiber Adhesive Generator K]
Next, as shown in FIG. 1, the nanofiber adhesive generating part K is located between the nanofiber generating part J, the adhesive and the nanofiber collecting part L, and is made of polypropylene (or polypropylene). A nanofiber-like adhesive N2 is sprayed on the surface which becomes the base material N3 of the filter of this embodiment with a rough non-woven fabric (or woven or net).
Basically, the adhesive N2 is sprayed onto the substrate N3 in the form of nanofibers from the nozzle portion 61 as shown in FIGS. 8 and 9 immediately before the nanofibers are collected on the substrate N3. When the adhesive N1 becomes a film and fills the gaps between the nanofibers, good air permeability of the folded nanofibers is hindered. Therefore, it is necessary that the adhesive N1 be as thin as possible, be as thin as possible, and be securely bonded to the substrate N3.
In FIG. 1, the adhesive spraying part 6 of the nanofiber adhesive generating part K is arranged in the lower part of the center, and the two nozzle parts 61 together on the upper and lower sides of the base material moving part 72 with respect to the surface of the base material N3 In parallel, a distance of 110 cm (nanofiber generation width) is reciprocated. This is because the adhesive N2 does not need to be laminated like a nanofiber layer, and if the nanofiber N1 is firmly fixed to the substrate N3, it is preferable that the adhesive N2 be less.

In this example, EVA hot melt adhesive (MORESCO Morescommelt TN-111) was used as the adhesive.
The composition of this adhesive is as follows.

Ethylene-vinyl acid copolymer: 15-25% weight Tackifier: 53-63%
Solid paraffin: 5 to 15%
Mineral oil ... 5 to 15%
Olefin copolymer ... 5% or less Additive ... 2% or less

Since the viscosity of the adhesive is lower at a higher temperature and the viscosity at 180 ° C. is 300 (mPa · s), a heater 62 is provided in the nozzle portion 61 so that it can be used in this state. is there.
Here, details of the adhesive spraying part 6 and the nozzle part 61 will be described with reference to FIGS. 1, 8 and 9. The adhesive pump 614 is heated by the supply pump 614 from the adhesive supply part 612 heated to about 180 ° C. It is supplied from the supply pipe 613 to the central nozzle 611 having a tip nozzle diameter of 0.15 mm. A cylindrical air blowing nozzle 615 is provided so as to wrap the outer cylinder at the tip of the center nozzle 611, and high-speed air is ejected from the cylindrical air blowing nozzle 615 toward the base material N 3 so as to draw the adhesive from the center nozzle 611. Spray. At this time, the entire nozzle section 61 is heated to about 200 ° C. by the heater 62 from the ejection area of about 1 mm ² through the air supply pipe 616 at 50 liters / minute by the air pump 617 that blows air, and the ejection air is also about 180 ° C. It is heated and heated to a certain degree so that the adhesive maintains 180 ° C. even at the nozzle tip.
With such a configuration, it has been found that two nanofiber adhesives having a diameter of 200 nm to 400 nm are generated without using the ESD method, although it is somewhat thicker than this method. The adhesive melted in a fiber shape is sprayed on the polypropylene substrate N3 so as to stick in a zigzag manner, and is applied uniformly to the whole.

[Nanofiber collecting part L1 and filter forming part L2 (collecting part L)]
Next, the collection part L of a nanofiber is demonstrated.
As shown in FIG. 1, the nanofiber collecting portion 8 (L1) of the nanofiber collecting portion L is formed from a polypropylene PP non-woven fabric having rough and strong eyes, which serves as a filter substrate 7, from the bottom to the top. A lower feed roller 81 and an upper hood roller 82 for moving in a screen form are provided, and between these rollers, a strong flat surface holding is required to keep the polypropylene substrate N3 and the nanofiber N1 vertical. A wire mesh 83 is provided, and a suction duct 84 is disposed behind the wire mesh 83 to attract the nanofibers N1 to the base material N3, and the nanofibers N1 are passed through the planes of the plane holding wire mesh 83 and the base material N3. Suction using suction air (suction negative pressure 200 Pa) by a suction pump (not shown), and using the fact that suction force increases at a rough spot in the lower position, Nanofibers are attracted in location, as a result, the amount that passes through the air becomes uniform size of the eye of the nanofiber layer is also to be uniform.
Here, the operation of the nanofiber collecting part L1 and the filter forming part L2 (L) will be described. The base material supply part 71 of the base material 7 is a non-woven polypropylene PP non-woven fabric, and hardly passes air. The base material 7 (N3) which does not hinder is wound up. The shaft of the base material supply unit 71 is rotated so as to unwind the base material 7 (N3) when the apparatus is in operation, and a predetermined amount of the base material 7 is transferred by the feed roller 81 to the plane holding wire net 83 of the base material moving unit 72. To send.
The base material N3 fed from the feed roller 81 moves upward on the plane holding wire mesh 83. First, the nanofiber adhesive N2 is sprayed and applied, but the temperature of the adhesive is The nanofiber N1 produced | generated in the nanofiber production | generation part J is laminated | stacked on the adhesive agent N2 next.

Next, the filter forming portion L2 will be described. For the time being, the bottom layer is a polypropylene base (N3) layer, the intermediate layer is an adhesive (N2) layer, and the top layer is a polyethersulfone (PES) nanofiber N1. The layer is fed by changing the direction by the upper feed roller 82, but is not yet completely bonded, so that the adhesive N2 is heated again through the heating roller 85 to recover the bonding function, and the heating roller In 85, the adhesive (EVA) N2 is heated to a predetermined temperature, and pressure is applied by bending these laminates, and N1, N2, and N3 are bonded together and wound by the filter winder 73 to obtain a product. To complete.
Here, the heating temperature of the heating roller 85 for heating the adhesive N2 is important. That is, if the heating temperature is low, the adhesion is not complete, and the nanofibers N1 and the substrate N3 are easily peeled off. If the heating temperature is too high, the adhesive strength is increased, but an ethylene-vinyl acid copolymer or the like. This adhesive becomes a film and closes the gaps (eyes) between the nanofibers of polyethersulfone (PES), impedes the passage of air through the filter and lowers the filter function.
In this embodiment, the heating temperature of the heating roller 85 is set to 71.degree. This is a nanofiber-like, not melted and not very bonded, as shown in the 1000 × micrograph of the filter at 70 ° C., but at 71 ° C. the 1000 × micrograph of the filter at FIG. As shown in Fig. 12, it melts somewhat and exhibits an adhesive function. At 75 ° C, it becomes a film as shown in the 1000 × micrograph of the filter in FIG. It is supposed to be.

Here, the experimental result which compared the performance of the filter using the nanofiber manufactured in the present Example with the conventional commercial HEPA air filter is shown.
[Comparative filter]
Nippon Inorganic Co., Ltd. HEPA air filter (Atmos GC (trademark) collection efficiency K),
Thickness 29mm: 1 layer
[Nanofiber filter of this example]
Substrate + nanofiber: thickness 0.335Mm～0.42Mm, 1 layer substrate: polypropylene nonwoven, the thickness of the substrate 0.255Mm～0.36Mm, basis weight 0.007 g / cm ^2,
Adhesive: ethylene-vinyl acid copolymer, diameter 200 nm to 400 nm, basis weight 0.00036 g / cm ² ,
Nanofiber material: Polyethersulfone (PES)
Diameter 100nm~50nm, basis weight 0.0004g / cm ^2,
[Prerequisites for the experiment]
The measurement conditions for the experiment are in accordance with JIS B 9927: 2000 “Clean Air Filter Performance Test Method”, each sample is 15 cm × 15 cm in area, the wind pressure is 65.67 liters / minute, and the particle counter (measuring instrument) : Nippon Kanomax Co., Ltd., MSP1000XP (measuring light scattering intensity from particles)), the number of 0.3 μm dust was measured at the inlet and outlet.
[Experimental result]
Comparative example: pressure loss 98 Pa collection efficiency 90%
Example: Pressure loss 30 Pa Collection efficiency 95%
As described above, the filter using the nanofibers of this example is 0.335 mm to 0.42 mm (0.16 mm to 0.08 mm: only nanofibers) and thinner than the conventional 29 mm HEPA filter, and Although the collection rate is as high as 95% compared to 90% in the conventional comparative example, the air pressure loss is as low as 30 Pa compared to the conventional 98 Pa, and the burden on the fan when used in an air conditioner is Remarkably reduced.

As described above, the filter using the nanofiber according to the embodiment of the present invention and the manufacturing method thereof are a combination of the electrostatic induction ESD method and the high-speed air flow, and the metal sphere is made as small as possible. The distance B between the bottom surface 311 of the sphere 31 and the spinning nozzle opening 211 can be shortened, and the high voltage 13 kv to 3 kv can be reduced. Hereinafter, advantages of the present embodiment are as follows.
1. The production amount per spinning nozzle has a production capacity equivalent to 1000 to 3000 spinning nozzles that do not use conventional high-speed airflow.
2. By reducing the metal sphere, the distance B between the bottom surface 311 of the metal sphere 31 and the spinning nozzle opening 211 can be shortened.
3. The high voltage can be lowered from 13 kv to 3 kv.
4). Since the space of the generating unit Y composed of the metal ball 31, the spinning nozzle 21, and the jet nozzle 41 for high-speed airflow can be reduced, and the plurality of generating units Y are arranged in parallel, the overall size is reduced. Mass production is possible by greatly increasing the amount of spinning.

5. The nanofiber adhesive generator K heats the adhesive and sprays it from the center nozzle, and sprays high-temperature high-speed air around the center nozzle so that nanofiber adhesive can be generated with a simple device. can do.
6). Adhesion between the base material N3 and the nanofiber N1 is performed at a predetermined temperature and pressure so that the adhesive of the nanofiber becomes a film and does not block the nanofiber. A filter having both strength and low pressure loss and strength can be manufactured.
This is different from the conventional filter using nanofibers, in which the nanofibers are simply sandwiched between the substrates, and the position of the nanofibers does not shift over time, and the strength of the substrate In addition, it can be manufactured in a state where the function of having a high collection rate and low pressure loss, which are characteristics of a filter using nanofibers, is not impaired as much as possible.
7). Since the nanofiber generator J, the nanofiber adhesive generator K, and the adhesive and nanofiber collector L do not need to be linked and charged as in the conventional case, they can be separated and the apparatus is simple. Maintenance is also simple, temperature and humidity management is simple, running costs are low, and scalability is high.
8). The inside of the apparatus of the nanofiber collecting part L1 is sucked with a duct to make a negative pressure, and the diluted flammable organic solvent is collected in the scrubber and does not leak outside.
9. Since the back surface of the plane holding wire net of the nanofiber collecting portion L1 is sucked with a duct to make a negative pressure, the suction force is increased at a coarse portion of the nanofiber in the lower position. The nanofibers at the upper position are attracted to the part, and as a result, the size of the nanofiber layer becomes uniform, and the amount of air passing through is uniform.
Needless to say, the present invention is not limited to the above-described embodiments as long as the features of the present invention are not impaired .

J ・ ・ Nanofiber production part, K ・ ・ Nanofiber adhesive production part,
L ・ ・ Collecting part, L1 ・ ・ Nanofiber collecting part,
L2 ・ ・ Filter forming part,
M ·· Generator frame,
E ... Electric field lines, G ... Grounding,
N1 ... Polymer solution (PES), N2 ... Adhesive (EVA),
N3 ・ ・ Base material (PP non-woven fabric)
X ... High-speed airflow, Y ... Generation unit,
1 .... Material supply section (material container), 11 .... Gear pump (discharge means),
12 .... Supply piping,
2 .... Spinning nozzle part, 21 ... Spinning nozzle, 211 ... Spinning nozzle opening,
22 .. Induction cylinder, 23 .. Heater (heater),
3 .. Electrode part, 31 .. Metal sphere, 311 .. Bottom surface, 33 .. High voltage power supply,
4 .... High-speed air current injection nozzle part, 41 .... Injection nozzle, 411 ... Open,
42 .... High pressure pump 6 ... Adhesive spraying part 61 ... Nozzle part
611 .. Central nozzle (adhesive), 612 .. Adhesive supply section,
613 ... Adhesive supply pipe, 614 ... Supply pump,
615 .... Cylinder air blowing nozzle, 616 ... Air supply pipe, 617 ... Air pump,
62 .. Heater,
7 .. Base material 71.. Base material supply section 72.. Base material movement section
73 .. Filter winding part,
8 .. Nanofiber collecting part 81.. Lower feed roller 82.. Upper feed roller 83..
84 .. Suction duct, 85 .. Heating roller,

Claims (3)

Between the non-woven fabric substrate having coarser eyes than the produced filter and the nanofiber layer in which the nanofiber material having a diameter of 100 nm to 50 nm has a uniform thickness, the nanofiber diameter is 200 nm to A filter in which EVA hot melt adhesive produced at 400 nm is disposed,
The adhesive is disposed on the base material in a zigzag shape, and the base material and the nanofiber layer are bonded so that the eyes of the nanofibers forming the filter are not covered with a film. Filter using. The filter using nanofibers according to claim 1, wherein the basis weight of the nanofibers of the filter is 0.0004 g / cm ² . Basis weight of the nonwoven fabric as a base material, a filter using a nanofiber according to claim 1 or 2, characterized in that it is 0.007 g / cm ^2.