JP4939254B2 - Nonwoven fabric manufacturing apparatus and nonwoven fabric manufacturing method - Google Patents

Description

  The present invention relates to a method for depositing nanofibers made of a polymer substance to produce a nonwoven fabric, and a nonwoven fabric production apparatus.

  An electrospinning (charge-induced spinning) method is known as a method for producing a filamentous material (hereinafter referred to as “nanofiber”) made of a polymer material and having a submicron-scale diameter.

  This electrospinning method is a method of obtaining nanofibers by flowing out (injecting) a polymer solution in which a polymer substance is dispersed in a solvent from a needle-like nozzle to which a high voltage is applied. More specifically, the charge density increases as the solvent of the polymer solution charged by a high voltage evaporates. A phenomenon (electrostatic explosion) in which the polymer solution is explosively stretched linearly occurs when the repulsive Coulomb force generated in the polymer solution exceeds the surface tension of the polymer solution. This electrostatic explosion occurs one after another in the space, so that nanofibers made of a polymer having a submicron diameter are manufactured.

  In addition, by depositing nanofibers manufactured by the above-mentioned method on a substrate, a three-dimensional thin film having a three-dimensional network can be obtained, and by forming a thicker film, a high thickness having a submicron network can be obtained. A porous web (nonwoven fabric) can be produced.

  The web produced by using the electrospinning method is highly porous with nano-order pores and has a large surface area, so it can be applied to filters, battery separators, polymer electrolyte membranes and electrodes of fuel cells, etc. It is expected to obtain a high effect.

Conventionally, as a method for producing a large amount of nanofibers to produce a practical web made of nanofibers, an apparatus for producing a web by arranging a plurality of nozzles in parallel and depositing a large amount of nanofibers has been proposed. (For example, refer to Patent Document 1).
JP 2002-201559 A

  However, as described above, when manufacturing nanofibers, a volatile solvent constituting the raw material liquid stays at a predetermined concentration in the nanofiber manufacturing space. On the other hand, a high voltage is applied to the nozzle for injecting the raw material liquid, and it is difficult to completely avoid the possibility of discharge. Therefore, when the solvent is made of a flammable substance, there is always a risk of explosion.

  On the other hand, it is possible to employ a non-flammable solvent, but considering environmental issues, the choices of substances that can be employed as a solvent are narrowed, which affects the cost.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a nanofiber manufacturing apparatus capable of avoiding the risk of explosion in manufacturing nanofibers and expanding the types of solvents selected. To do.

  In order to achieve the above object, a nanofiber manufacturing apparatus according to the present invention is a nanofiber manufacturing apparatus including a nozzle hole for applying a voltage, for injecting a raw material liquid for manufacturing nanofibers. Is provided with a gas supply source for supplying a low-oxygen gas to make a low-oxygen atmosphere, and a partition for maintaining the nanofiber manufacturing space in a low-oxygen atmosphere rather than the atmosphere in the outer space.

  As a result, the nanofiber manufacturing space is maintained in a low-oxygen atmosphere, so that the risk of explosion can be avoided as much as possible even when a flammable solvent is present in the space. Become.

  The gas supply source may supply a gas having a higher nitrogen concentration than the outer space to the nanofiber manufacturing space.

  By introducing a gas having a high nitrogen concentration, the oxygen concentration in the nanofiber manufacturing space can be relatively lowered. In addition, since nitrogen gas is inert and easily available, an atmosphere having a low oxygen concentration can be easily formed in the nanofiber manufacturing space. The gas having a high nitrogen concentration may be a gas having a higher nitrogen concentration than the atmosphere, and may be a gas having a nitrogen concentration close to 100%.

  The gas supply source may supply superheated steam to the nanofiber manufacturing space.

  When superheated steam is introduced as a gas supplied to the inner space of the partition wall, the superheated steam can easily raise the temperature of the injected raw material liquid by radiant heat transfer, convective heat transfer, and agglomerated heat transfer. Therefore, even when a hardly volatile solvent is used as the solvent of the raw material liquid, electrostatic explosion can be easily caused. Therefore, it is possible to expand the range of solvents that can be used, such as non-flammable but hardly volatile solvents, and explosion protection can be considered at the stage of solvent selection. Furthermore, since superheated steam has a low oxygen concentration, it is possible to prevent explosion by setting the nanofiber manufacturing space in a low oxygen state.

  Here, the explosion means an explosion that occurs when the solvent of the raw material liquid volatilizes and stays in the nanofiber manufacturing space, and the solvent ignites for some reason (for example, discharge or the like). Explosion-proof means that the explosion does not occur. The explosion is different from the electrostatic explosion necessary for producing nanofibers.

  Further, a gas supply amount changing means for changing a gas supply amount from the gas supply source to the nanofiber manufacturing space, a gas composition measuring means for measuring a gas composition in the nanofiber manufacturing space, and the gas composition measuring means And a control means for controlling the gas supply amount changing means so as to maintain a low oxygen atmosphere in the nanofiber manufacturing space based on a signal from.

  Furthermore, a gas supply amount changing means for changing the gas supply amount from the gas supply source to the nanofiber manufacturing space, a pressure measuring means for measuring the pressure in the nanofiber manufacturing space, and a signal from the pressure measuring means And a control means for controlling the gas supply amount changing means so as to maintain the pressure in the nanofiber manufacturing space at a positive pressure.

  Further, a gas temperature changing means for changing the temperature of the gas supplied from the gas supply source, a temperature measuring means for measuring the temperature of the nanofiber manufacturing space, and the nanofiber manufacturing based on a signal from the pressure measuring means Control means for controlling the gas temperature changing means so as to maintain the space at a predetermined temperature may be provided.

  By controlling the atmosphere of the nanofiber production space to be constant as described above, it is possible to produce high quality nanofibers.

  Furthermore, you may provide the exhaust means which exhausts the gas which forms the atmosphere of the said nanofiber manufacturing space.

  By exhausting the nanofiber manufacturing space as described above, the atmosphere of the nanofiber manufacturing space can be derived to a certain place. Therefore, it is possible to consider the environment where the nanofiber manufacturing apparatus is installed. In particular, when the nanofiber manufacturing space is sealed with a partition, it is particularly useful for controlling the atmosphere inside the partition. In other words, taking into account the injection amount of the raw material liquid for nanofiber production, the balance between the gas supply amount from the gas supply source and the exhaust amount of the atmosphere by the exhaust means makes it possible to produce nanofibers sealed by the partition walls. It becomes possible to keep the atmosphere of the space constant.

  Moreover, the said objective can also be achieved by the nanofiber manufacturing method concerning this invention. That is, in a nanofiber manufacturing method in which a raw material liquid for manufacturing nanofibers is injected from an injection hole to which a voltage is applied, and nanofibers are manufactured by electrostatic explosion in the nanofiber manufacturing space, It can also be achieved by supplying a low oxygen gas as an atmosphere to the nanofiber manufacturing space and manufacturing the nanofiber in the low oxygen atmosphere, and the effect is the same as described above.

  According to the present invention, it becomes possible to manufacture nanofibers safely.

  Next, embodiments of the nanofiber manufacturing apparatus and the nonwoven fabric manufacturing apparatus according to the present invention will be described together.

FIG. 1 is a perspective view schematically showing a non-woven fabric manufacturing apparatus according to the present invention.
As shown in the figure, the nonwoven fabric manufacturing apparatus 100 includes a nanofiber manufacturing apparatus 101, and includes a partition wall 102, a gas supply source 103, an exhaust apparatus 105 as an exhaust means, and a compression means 300. In addition, since it is not possible to clearly distinguish the manufactured nanofiber or the raw material liquid, the reference numeral 200 is assigned to each, and the manufactured nonwoven fabric is assigned 210.

  The nanofiber 200 can be selected from petroleum polymer materials such as polyvinylidene fluoride (FVDF), polyvinylidene fluoride-cohexafluoropropylene, and polyacrylonitrile, and copolymers and mixtures thereof. The material and the combination thereof may be arbitrarily selected depending on the desired function such as the property and performance.

  Examples of the solvent include acetone and DMF (N, N-dimethylformamide).

  In addition, the material of the said nanofiber and the kind of solvent are illustrations. In particular, the type of solvent is variously selected depending on the type of introduced gas and the ambient temperature described later.

  The partition wall 102 is a non-breathable member that covers almost the entire nonwoven fabric manufacturing apparatus 100. For example, a resin-made panel can be assembled into a box shape, or a metal frame that is stretched with a flexible and air-permeable sheet can be listed. Note that a floor on which the nonwoven fabric manufacturing apparatus 100 is placed may be used as the partition wall 102.

  The inner space closed by the partition wall 102 includes a nanofiber manufacturing space 107 in which nanofibers are manufactured. The inner space and the outer space other than the space surrounded by the partition wall 102 are isolated in an airtight state. I don't mean.

  The gas supply source 103 is a device that supplies gas to the inner space surrounded by the partition wall 102. Examples of the gas supplied from the gas supply source 103 include a low oxygen concentration gas obtained by removing oxygen from air to some extent by a resin membrane (hollow fiber membrane), and superheated steam. Here, the low oxygen concentration is based on the oxygen concentration in the nanofiber manufacturing space 107 when the nanofiber is manufactured without being surrounded by the partition wall 102 and without supplying gas in the atmosphere near the normal ground surface. Also means a low concentration. This description does not exclude the use of high-purity gas containing almost no oxygen, but carbon dioxide supplied from high-purity nitrogen or dry ice sealed in a cylinder in a liquid or gas state. Etc. are also available.

Hereinafter, in the present embodiment, a case where superheated steam is employed as the low oxygen gas will be described.
The exhaust device 105 is a device that can exhaust the atmosphere present in the inner space of the partition wall 102. In the case of the present embodiment, a recovery device that can recover a solvent or the like contained in the exhausted atmosphere is attached to the exhaust device 105.

  The inner space of the partition wall 102 can be maintained at a positive pressure by the balance between the gas supply amount of the gas supply source 103 and the gas exhaust amount of the exhaust device 105. The positive pressure means a state in which the pressure in the inner space is higher than the pressure in the outer space of the partition wall.

  The nanofiber manufacturing apparatus 101 includes nanofiber generating means 110 and a collecting electrode 120.

  The nanofiber generating means 110 is a device for injecting (flowing out) a raw material liquid for producing nanofibers, and is connected to a power source 150 and maintained at a predetermined potential. A pipe 111 connected to a tank (not shown) for storing the raw material liquid is connected to the nanofiber generating means 110 so that the raw material liquid is supplied at a predetermined pressure.

FIG. 2 is a diagram showing a specific example of the nanofiber generating means.
The nanofiber generating means 110 shown in FIG. 1A includes a plurality of nozzles 113 each having an injection hole 112 at the tip, and a power source 150 is connected to each nozzle 113. Each nozzle 113 is connected to a pipe 111, and the raw material liquid is supplied at a predetermined pressure from a tank that stores the raw material liquid.

  The nanofiber generating means 110 shown in FIG. 5A injects the raw material liquid 200 from the injection hole 112 by the supplied pressure, and the injected raw material liquid 200 is charged by the power source 150 connected to the nozzle 113. It is supposed to be.

  The nanofiber generating means 110 shown in FIG. 5B includes a cylindrical barrel 114 having a large number of injection holes 112 on the peripheral wall. The barrel 114 is rotatable and is maintained at a predetermined potential by the power source 150. Further, a pipe 111 is connected to one of the shafts provided on the rotating shaft, and the raw material liquid 200 is supplied into the barrel 114.

  The nanofiber generating means 110 shown in FIG. 6B is for injecting the raw material liquid 200 from the injection hole 112 by centrifugal force, and the injected raw material liquid 200 is charged by the power supply 150 connected to the barrel 114. It has become.

  The sheet 160 is a member on which the nanofibers 200 generated in the space are deposited, and is a thin and flexible long sheet made of a material that can be easily separated from the deposited nanofibers 200.

  The sheet 160 is supplied in a state of being wound in a roll shape, and slowly moves in the direction of the arrow in the drawing by the moving means 170 through the portion where the nanofibers 200 are deposited. And it rolls around with the nonwoven fabric 210 manufactured on the sheet | seat 160 again in roll shape. A supply roll (not shown) around which the sheet 160 is wound and a roll (not shown) wound together with the nonwoven fabric 210 are accommodated in the inner space of the partition wall 102.

  The moving means 170 is a device capable of feeding the sheet 160 in one direction while maintaining a predetermined tension, and moves the sheet 160 by rotating a roller shown in the drawing by driving a motor (not shown) or the like. Is.

  The collection electrode 120 is a metal electrode to which a potential is applied by the power source 150 so as to generate a predetermined potential difference from the nanofiber generation means 110. The collecting electrode 120 is disposed on the opposite side of the nanofiber generating means 110 with respect to the sheet 160 and facing the nanofiber generating means 110. Further, the collecting electrode 120 has a function of electrically attracting the charged nanofibers 200 generated by being ejected from the nanofiber generating means 110 and depositing the nanofibers 200 on the sheet 160.

  The collecting electrode 120 has a plurality of modes for making the density distribution of the deposited nanofibers uniform. Hereinafter, each aspect of the collection electrode 120 will be described.

(Collecting electrode <1>)
FIG. 3 is a perspective view conceptually showing the collecting electrode <1>.

  As shown in the figure, the collecting electrode 120 includes a plurality of electrodes 121, a power source 150 that applies a potential to each of the plurality of electrodes 121, and a voltage changing unit that can periodically change the voltage applied to the electrodes 121. 151 and an insulator 130.

  The electrode 121 is a metal member that extends in the moving direction of the sheet 160 (arrow in the drawing) and is disposed over a portion where the nanofibers 200 are deposited, that is, the deposition portion 161. In the case of the main collection electrode <1>, six electrodes 121 are arranged perpendicular to the moving direction of the sheet 160, and an insulator 130 is provided between the electrodes. Note that in the case where each of the electrodes 121 is shown separately, the description will be made by adding a to f to the reference numerals.

  The power supply 150 is a device that can apply a potential of a maximum of −50 kv to −100 kv. In the case of the main collection electrode <1>, a power source 150a to a power source 150f are connected to the electrodes 121a to 121f, respectively, and a potential is applied to each electrode 121 independently.

  The voltage changing unit 151 is a device that can change the potential applied to the electrode 121 in a voltage range of about 10 kv to 100 kv.

  With the collection electrode 120 having the above configuration, the distribution of the electric field generated on the sheet 160 can be arbitrarily changed by changing the potential of each electrode 121 by the voltage changing means 151. Therefore, the position where the collection of the charged nanofibers 200 is concentrated can be moved according to the electric field distribution, and the thickness of the deposited nanofibers 200 can be made uniform.

(Collecting electrode <2>)
Next, another collecting electrode 120 will be described.

FIG. 4 is a side view conceptually showing another collecting electrode <2>.
As shown in the figure, the collecting electrode 120 includes a plurality of electrodes 121, a power source 150 that applies a potential to each of the plurality of electrodes 121, a driving unit 157 that drives the electrodes 121, and an insulating plate 159. .

Since the electrode 121 and the power source 150 are the same as those of the collecting electrode <1>, description thereof is omitted.
The drive means 157 can reciprocate each electrode 121 linearly independently, and includes a moving shaft 158 that linearly protrudes and retracts due to air pressure. The driving unit 157 may be a linear actuator, and any driving method using pneumatic pressure or hydraulic pressure, using a ball screw, using a linear motor, or the like may be used. The driving unit 157 moves the electrode 121 along a line connecting the electrode 121 and the nanofiber generation unit 110.

  The insulating plate 159 has a function of preventing vibrations during movement of the electrodes 121 and preventing abnormal discharge and the like by inhibiting contact and proximity between the electrodes 121.

  With the collecting electrode 120 as described above, the voltage output from the power supply 150 may be constant. Further, by controlling the movement of each electrode 121, it is possible to form an analog electric field that changes with time for each region of the stacking portion 161 of the sheet 160 divided in the direction perpendicular to the moving direction of the sheet 160. It becomes.

(Collecting electrode <3>)
Next, other collecting electrodes 120 will be described.

FIG. 5 is a perspective view conceptually showing another collecting electrode <3>.
As shown in the figure, the collecting electrode 120 includes an electrode 121, a power supply 150 that applies a potential to the electrode 121, and a driving unit 167 that drives the electrode 121.

Since the power supply 150 is the same as that of the collecting electrode <1>, the description thereof is omitted.
The driving means 167 can reciprocate the electrode 121 linearly along the rail. The driving means 157 may be a linear actuator as described above, and any driving method using pneumatic pressure or hydraulic pressure, using a ball screw, using a linear motor, or the like may be used. The driving unit 167 moves the electrode 121 along the width direction of the sheet 160, that is, along a line perpendicular to the moving direction of the sheet 160.

  With the collecting electrode 120 as described above, the voltage output from the power supply 150 may be constant. Further, by controlling the movement of the electrode 121, an electric field that changes in a direction perpendicular to the moving direction of the sheet 160 can be formed in the stacking portion 161 of the sheet 160.

  When the electric field is changed by the collecting electrode 120 as in the present embodiment, the possibility of discharge from the sliding portion of each electrode 121 is increased, and therefore an explosion-proof measure for the nanofiber manufacturing space 107 is required. Therefore, it can be said that it is a preferable aspect to make the nanofiber manufacturing space 107 into a low oxygen state.

FIG. 6 is a perspective view showing the compression means.
FIG. 7 is a cross-sectional view showing the compression means.

  As shown in the figure, the compression means 300 compresses the nonwoven fabric 210 made of the deposited nanofibers 200. The compression means 300 is a device that can supply the superheated steam 350 to the inner space of the partition wall 102 while spraying the superheated steam 350 supplied from the gas supply source 103 onto the nonwoven fabric 210 (nanofiber 200).

  The compression unit 300 includes a compression roller 301, a pinch roller 303, a pressing unit 305, a driving unit 306, gears 307 and 308, and a shaft 309.

  The compression roller 301 is a cylindrical tube that continuously presses the non-woven fabric 210 that moves together with the sheet 160, and the spray holes 302 are formed radially on the peripheral wall of the tube.

  The shaft 309 is a cylindrical member closed at one end and disposed so as to penetrate the compression roller 301 coaxially with the rotation axis of the compression roller 301. In the peripheral wall of the shaft 309, a large number of holes for discharging the superheated steam 350 are formed radially like the compression roller 301.

  The shaft 309 and the compression roller 301 are connected via bearings 310 attached to both ends of the compression roller 301 in order to rotatably support the compression roller 301 with the shaft 309 fixed.

  The pinch roller 303 is a roller that cooperates with the compression roller 301 and sandwiches the nonwoven fabric 210 and the sheet 160, and is pivotally supported so as to rotate as the sheet 160 moves.

  Here, the gas supply source 103 is connected to the open end of the shaft 309 by a flexible pipe, and superheated steam generated by the gas supply source 103 is introduced into the shaft 309 and is passed through a hole formed in the shaft 309. Thus, the superheated steam is introduced into the large-diameter compression roller 301.

  Thereby, a pipe can be easily connected to the shaft 309 that does not rotate, and superheated steam can be introduced into the compression roller 301. Furthermore, by introducing superheated steam into the compression roller 301 via the one-end shaft 309, it is possible to discharge the superheated steam from the compression roller 301 evenly into the inner space of the nonwoven fabric 210 and the partition wall 102.

  The pressing unit 305 is a device that presses the compression roller 301 toward the pinch roller 303 by air pressure, and includes a cylinder 311 and a moving shaft 312. The moving shaft 312 is connected to both ends of the shaft 309, and presses the compression roller 301 rotatably via the shaft 309 by causing the moving shaft 312 to protrude from the cylinder 311 by air pressure.

  Therefore, the nonwoven fabric 210 sandwiched between the compression roller 301 and the pinch roller 303 is compressed by the force of the pressure of the pressing means 305.

  The driving unit 306 is a device that forcibly rotates the compression roller 301, and includes a stepping motor and a gear 308. The gear 308 meshes with a gear 307 attached toward the outer side of the end face of the compression roller 301. Accordingly, the driving unit 306 can accurately control the rotation of the compression roller 301 by controlling the driving of the stepping motor.

  By controlling the driving means 306 and synchronizing the rotation of the compression roller 301 and the movement of the nonwoven fabric 210 (sheet 160), the nonwoven fabric 210 can be compressed without the nonwoven fabric 210 being twisted.

  Further, as shown in FIG. 8, an AC voltage can be applied to the compression roller 301 by an AC power source 360. By applying an AC voltage to the compression roller 301 that is in direct contact with the charged nonwoven fabric 210, the nonwoven fabric 210 can be neutralized, and the nonwoven fabric 210 can be prevented from adhering to the compression roller 301. . In addition, when the nonwoven fabric 210 is neutralized by the superheated steam 350, the AC power supply 360 for neutralization may be unnecessary.

FIG. 9 is a block diagram illustrating a functional configuration of the nonwoven fabric manufacturing apparatus 100 together with a mechanism unit.
As shown in the figure, the nonwoven fabric manufacturing apparatus 100 has a gas composition sensor 191 as a gas composition measuring unit, a temperature sensor 192 as a temperature measuring unit, and a pressure sensor 193 as a pressure measuring unit in addition to the above-described configuration. Is provided in the inner space of the partition wall 102. In addition, the nonwoven fabric manufacturing apparatus 100 includes a gas supply amount changing unit 104 and an exhaust fan 106.

  The gas composition sensor 191 is a device that can detect at least a specific gas from the atmosphere existing in the internal space of the partition wall 102 and provide a signal corresponding to the concentration. As the gas composition sensor 191, for example, a sensor that can detect oxygen and measure the concentration, a sensor that can detect nitrogen and measure the concentration, and the like can be used. Moreover, what can distinguish and detect the kind of gas which atmosphere has, and can measure those ratios may be used.

  The temperature sensor 192 is a sensor that can measure the temperature of the internal space of the partition wall 102 and provide a signal corresponding to the temperature. For example, a thermocouple, an infrared thermometer, etc. are mentioned. Note that an infrared thermometer can measure the temperature of the inner space even from the outer space of the partition wall 102.

  The pressure sensor 193 is a sensor that can provide a signal corresponding to the pressure in the inner space of the partition wall 102. For example, a sensor that can convert a minute displacement of the diaphragm into an electrical signal can be exemplified.

  The gas supply amount changing means 104 is arranged in the middle of the pipe inserted from the gas supply source 103 to the inner space of the partition wall 102, and adjusts the amount of gas flowing through the pipe by the valve, that is, the gas flow rate. In addition, the amount of gas supplied from the gas supply source 103 to the space in the partition wall 102 can be changed. The gas supply amount changing means 104 in the present embodiment can completely close the inside of the pipe.

  The exhaust fan 106 is provided inside the exhaust device 105, and can rotate the fan to suck the atmosphere in the inner space of the partition wall 102 through a pipe inserted from the exhaust device 105 to the inner space of the partition wall 102. It is possible. Further, the exhaust device 105 is provided with opening / closing means that can select whether or not to exhaust, closer to the partition wall 102 than the exhaust fan 106.

  Moreover, as shown in the figure, the nonwoven fabric manufacturing apparatus 100 includes a main control unit 401, a displacement control unit 402, a temperature control unit 403, a supply control unit 404, and a composition signal acquisition unit 411 as functional units 400. A temperature signal acquisition unit 412, a pressure signal acquisition unit 413, and a voltage control unit 420.

  The composition signal acquisition unit 411 is a processing unit that acquires a signal from the gas composition sensor 191, converts the signal into a digital signal, and transmits the digital signal to the main control unit 401.

  The temperature signal acquisition unit 412 is a processing unit that acquires a signal from the temperature sensor 192, converts the signal into a digital signal, and transmits the digital signal to the main control unit 401.

  The pressure signal acquisition unit 413 is a processing unit that acquires a signal from the pressure sensor 193, converts the signal into a digital signal, and transmits the digital signal to the main control unit 401.

  The main control unit 401 is a processing unit that analyzes signals from the sensors 191, 192, and 193. Further, the processing unit performs feedback control of the gas supply amount changing unit 104 and the exhaust fan 106 via the supply amount control unit 404 and the exhaust amount control unit 402. From the above, the main controller 401 can maintain the inner space of the partition wall 102 in a predetermined atmosphere. The main control unit 401 controls the temperature of the superheated steam 350 supplied to the inner space of the partition wall 102 by controlling a superheated steam generator described later provided in the gas supply source 103 via the temperature control unit 403. It is possible. In addition, the main control unit 401 controls the power supply 150 that applies a potential to the nanofiber generation unit 110 and the collection electrode 120 via the voltage control unit 420, and between the nanofiber generation unit 110 and the collection electrode 120. It is possible to generate a predetermined voltage.

  The exhaust amount control unit 402 is a processing unit that is connected to the exhaust fan 106 and can control the amount of the atmosphere in the partition wall 102 to be sucked by controlling the rotational speed of the exhaust fan 106.

  The temperature control unit 403 is a processing unit that is connected to a superheated steam generator described later and can control the temperature of the superheated steam 350 supplied to the space in the partition wall 102.

  The supply amount control unit 404 is connected to the gas supply amount changing means 104 and can control the flow rate of the gas supplied from the gas supply source 103 by changing the open / close state of a valve provided in the gas supply amount changing means 104. It is a processing unit.

  The voltage control unit 420 is a processing unit that is connected to the power source 150 and can control the power source so that a predetermined voltage is generated.

  The superheated steam generator as the gas supply source 103 is an apparatus capable of heating saturated steam to 100 ° C. or higher with normal pressure and generating normal pressure superheated steam. In the case of the present embodiment, the temperature controller 403 can arbitrarily set the temperature of the superheated steam 350 supplied to the space in the partition wall 102 up to 500 degrees. In addition, there are two methods for heating saturated water vapor, such as heating with an electric heater and heating by burning fuel. In this embodiment, a plurality of metal pipes are bundled, and these metal pipes are induction-heated. The method of generating superheated water vapor by adopting saturated water vapor through each metal pipe.

  More specifically, the metal pipe is heated by a high frequency power source (frequency of 10 kHz to 60 kHz). Moreover, saturated water vapor | steam is supplied from a boiler.

Here, if a superheated steam generator is used as the gas supply source 103, superheated steam (H ₂ O gas) is supplied to the space in the partition wall 102. In this case, the oxygen concentration of the superheated steam supplied is 0.1% by volume to 15% by volume, and is usually maintained in the range of 0.3% by volume to 5.0% by volume. As described above, the space in the partition wall 102 can be made a low oxygen atmosphere by being filled with superheated steam having a low oxygen concentration.

  Moreover, since superheated steam has a high radiant heat transfer effect in addition to the convective heat transfer effect, it is possible to further promote the volatilization of the solvent constituting the raw material liquid 200 for producing nanofibers, thereby facilitating the production of nanofibers. be able to. That is, even when a hardly volatile solvent is used, the hardly volatile solvent evaporates due to the thermal energy applied from the superheated steam 350 in the nanofiber manufacturing space 107, thereby producing an electrostatic explosion to produce a nanofiber. It becomes possible. This means that the types of solvents to be selected can be expanded, and it is possible to employ a solvent that can be considered at low cost and in the environment.

Next, the entire arrangement of the nonwoven fabric manufacturing apparatus 100 will be described.
FIG. 10 is a side view schematically showing the nonwoven fabric manufacturing apparatus.

  As shown in the figure, the nonwoven fabric manufacturing apparatus 100 is surrounded by a partition wall 102. In addition, the nanofiber generating means 110 is directed to the sheet 160 disposed in the lower portion and the raw material liquid is jetted. The distance between the nanofiber generating means 110 and the sheet 160 is set to a distance at which electrostatic explosion occurs a plurality of times and nanofibers having a desired diameter are obtained.

  Further, the collecting electrode 120 disposed on the lower side of the sheet 160 generates a predetermined potential difference from the nanofiber generating means 110. These potential differences are adjusted by a power source 150 that is independently connected to the nanofiber generating means 110 and the collecting electrode 120. That is, the power supply 150 is configured such that the power supplied to the nanofiber generating means 110 and the power supplied to the collecting electrode 120 can be supplied independently.

  A compression roller 301 and a pinch roller 303 are disposed so as to sandwich the sheet 160 and the nonwoven fabric 210 on the downstream side of the collecting electrode 120 in the moving direction of the sheet 160 (arrow in the figure).

  The sheet 160 is supplied from a sheet supply roll 162 around which a long sheet 160 is wound, and the nonwoven fabric 210 in a compressed state is taken up by the take-up roll 163 together with the sheet 160.

Next, a method for manufacturing a nonwoven fabric using the nonwoven fabric manufacturing apparatus 100 having the above configuration will be described.
First, superheated steam 350 is supplied to the inner space of the partition wall 102. On the other hand, the atmosphere in the inner space of the partition wall 102 is sucked by the exhaust device 105. While the superheated steam 350 is supplied as described above, the atmosphere is sucked and the inner space of the partition wall 102 is in an equilibrium state at a predetermined temperature, a predetermined pressure, and a predetermined oxygen concentration. These oxygen concentration, temperature, and pressure are monitored by a gas composition sensor 191, a temperature sensor 192, and a pressure sensor 193, and the gas supply amount changing means 104, the exhaust fan 106, and the gas supply source 103 (as shown in FIG. The temperature at which superheated steam is generated is controlled.

  Next, the raw material liquid is injected from the plurality of injection holes 112 of the nanofiber generating means 110. Thereby, since the atmosphere in the inner space of the partition wall 102 changes, the temperature of the superheated steam generated by the gas supply amount changing means 104, the exhaust fan 106, and the gas supply source 103 (superheated steam generator) is controlled again.

  In the above atmosphere, the solvent evaporates from the raw material liquid for producing nanofibers, and electrostatic explosion is repeated, whereby nanofibers 200 are produced. Then, the manufactured nanofiber 200 is attracted to the collecting electrode, and the nanofiber is deposited on the sheet 160.

  The sheet 160 on which the nanofibers 200 are deposited is moving at a constant moving speed. Further, the moving speed of the sheet 160 is obtained by calculation from the speed at which the nanofibers 200 are deposited and the desired state of the nonwoven fabric 210 (for example, density).

  The nonwoven fabric 210 deposited and formed on the sheet 160 as described above is in a so-called fluffy state. The nonwoven fabric 210 in this state moves together with the sheet 160.

  In the downstream of the moving direction of the sheet 160, the compression roller 301 and the pinch roller 303 compress the fluffy nonwoven fabric 210 while raising the temperature of the portion compressed by superheated steam sprayed from the compression roller 301 to the nonwoven fabric 210. Then, the solvent remaining in the nonwoven fabric 210 is skipped and dried.

  Here, the thickness of the nonwoven fabric 210 is determined by the thickness of the nonwoven fabric 210 immediately after deposition and the setting of the pressing force of the pressing means 305. These settings are determined based on conditions such as the type of polymer constituting the nanofiber 200 and the solvent used.

  If a non-woven fabric is produced as described above, nanofibers are produced in a low oxygen atmosphere. Therefore, even if a flammable solvent is used as the solvent of the raw material liquid for producing nanofibers, the collecting electrode 120 and the like It is possible to prevent an explosion due to discharge from the pipe. Further, since the temperature of the raw material liquid is increased by superheated steam, it is possible to induce electrostatic explosion even when a hardly volatile solvent is employed. That is, if superheated steam is used, it is possible to expand the range of types of solvents that can be employed while preventing explosion.

  And it becomes possible to manufacture easily the nonwoven fabric 210 provided with desired thickness, a density, mechanical strength, and the surface area per unit volume in the state without the worry of an explosion.

  In the above embodiment, the shaft 309 that supports the compression roller 301 and the gas supply source 103 are connected, and the superheated steam 350 is introduced into the inner space of the partition wall 102 from the spray hole (302) provided in the peripheral wall of the compression roller 301. However, the present invention is not limited to this. For example, as shown in FIG. 10, a gas may be directly supplied to the inner space of the partition wall 102.

  The low-oxygen atmosphere may be in the nanofiber manufacturing space 107, that is, the space between the nanofiber generating means 110 and the collecting electrode 120. Therefore, as shown in FIG. 11, the partition wall 102 may surround only the vicinity of the nanofiber manufacturing space 107.

  Furthermore, the nanofiber manufacturing space 107 is sealed by the partition wall 102, and the partition wall 102 is balanced by balancing the amount of gas supplied from the gas supply source 103 with the exhaust amount by the exhaust device 105 and the injection amount of the raw material liquid for nanofiber manufacturing. It is also possible to maintain a constant atmosphere of the inner space sealed with a low oxygen state.

  Further, the gas exhausted by the exhaust device 105 may be introduced again into the partition wall 102. In this case, it is desirable because the amount of gas supplied from the gas supply source 103 can be suppressed and the temperature of the space in the partition wall 102 can be easily maintained.

  Further, a heater such as a sheath heater may be provided inside the partition wall 102, and the temperature of the space in the partition wall 102 may be kept constant. The gas supplied from the gas supply source 103 is heated by the heater, and the heated gas is supplied to the partition wall. By introducing into the internal space 102, the temperature of the internal space of the partition wall may be set to a predetermined temperature.

  Moreover, although the said embodiment showed the case where a nonwoven fabric was manufactured, this invention is applicable also to the spinning technique etc. which utilized nanofiber.

  INDUSTRIAL APPLICABILITY The present invention can be used for a nanofiber manufacturing apparatus, a non-woven fabric manufacturing apparatus that can be applied to a filter using microporosity, a catalyst carrier using a large surface area, and the like.

It is a perspective view which shows roughly a nonwoven fabric manufacturing apparatus provided with the nanofiber manufacturing apparatus concerning this invention. It is a figure which shows the specific example of a nanofiber generation | occurrence | production means. It is a perspective view which shows collection electrode <1> notionally. It is a side view which shows notionally the collection electrode <2>. FIG. 5 is a perspective view conceptually showing a collecting electrode <3>. It is a perspective view which shows a compression means. It is sectional drawing which shows a compression means. It is a figure which shows the static elimination structure of a compression temperature rising roller. It is a block diagram which shows the control structure of a nonwoven fabric manufacturing apparatus. It is a side view which shows notionally the manufacturing state of a nonwoven fabric. It is a side view which shows the other aspect of a partition notionally.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 Nonwoven fabric manufacturing apparatus 101 Nanofiber manufacturing apparatus 102 Partition 103 Gas supply source 104 Supply amount changing means 105 Exhaust apparatus 106 Exhaust fan 107 Nanofiber manufacturing space 110 Nanofiber generating means 112 Injection hole 120 Collection electrode 150 Power supply 160 Sheet 161 Deposition unit 191 Gas composition sensor 192 Temperature sensor 193 Pressure sensor 200 Nanofiber 200 Raw material liquid 210 Non-woven fabric 300 Compression means 301 Compression roller 309 Shaft 350 Superheated steam 400 Function unit 401 Main control unit 402 Exhaust amount control unit 403 Temperature control unit 404 Supply amount control unit 411 Composition signal acquisition unit 412 Temperature signal acquisition unit 413 Pressure signal acquisition unit 420 Voltage control unit

Claims (5)

A non-woven fabric manufacturing apparatus comprising a spray hole for applying a voltage for injecting a raw material liquid for producing nanofibers, and a depositing means for depositing the manufactured nanofibers,
A non-woven fabric manufacturing apparatus comprising a nanofiber manufacturing space and a gas supply source for discharging superheated steam to the nanofiber deposited on the volume-receiving means .   further,
  Compression means for compressing nanofibers deposited on the deposition means,
  The gas supply source releases superheated water vapor into the nanofibers compressed by the compression means.
The non-woven fabric manufacturing apparatus according to claim 1.   The compression means includes
  A cylindrical compression roller having blowing holes that are radially drilled in the peripheral wall;
  The gas supply source discharges superheated steam to the nanofibers deposited on the volume-receiving means through the spray holes of the compression roller.
The nonwoven fabric manufacturing apparatus according to claim 2.   A non-woven fabric manufacturing method for manufacturing a non-woven fabric by spraying a raw material liquid for manufacturing nano fibers from a spray hole to which a voltage is applied, and depositing the manufactured nano fibers on a deposition target,
  Superheated water vapor is emitted to the nanofiber manufacturing space and to the nanofibers deposited on the volumetric means.
Nonwoven fabric manufacturing method.   further,
  Compressing the nanofibers deposited on the deposition means by a compression means;
  Release superheated steam into compressed nanofibers
The method for producing a nonwoven fabric according to claim 4.

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