JP2007092237A - Method for producing fiber structure by electrospinning method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a means for stably producing a uniform fiber structure in a method for producing the fiber structure by an electrospinning method, more precisely, the method for producing the fiber structure of a fiber-forming material by the electrospinning method. <P>SOLUTION: The method for producing the fiber structure from the fiber-forming material by the electrospinning method comprises continuously introducing a noncondensable gas to at least one storing vessel (B) of a solution, connected to at least one spinning part (A) for spinning out the fiber-forming material-containing solution through at least one pressure controller (C), and sending the solution to the spinning part (A) by the pressure of the gas. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a method for producing a fiber structure by an electrospinning method. More specifically, the present invention relates to a method for stably producing a uniform fiber structure in a method for producing a fiber structure of a fiber-forming substance by electrostatic spinning.

  As a technique for spinning various fiber-forming substances, a melt-formed fiber-forming substance is spun from a nozzle, and this is cooled and solidified in the air or in a certain gas to obtain fibers. ”Or“ dry spinning method ”in which a solution containing a fiber-forming substance is spun from a nozzle and the solvent component is evaporated therefrom to obtain fibers. Similarly, the fiber-forming substance spun from the nozzle is added to the coagulation liquid. In general, a “wet spinning method” in which fibers are obtained by solidifying with a glass is known.

  In addition, the technology for producing a planar fiber structure is an application of the above-described spinning technology. In addition to the “dry method” and “wet method”, a process of drawing and opening is performed after melt spinning. "Spunbond method" to obtain a planar fiber structure, and "Meltblown method" to obtain a planar fiber structure through a drawing and opening process after blowing a high-temperature and high-pressure air stream to the melt spinning nozzle port Etc. are generally known.

  Various efforts have been made to use these spinning technology and fiber structure manufacturing technology to provide new characteristics not found in existing fibers and fiber structures. In particular, efforts are being made to impart new functions by minimizing the fiber diameter and improving the surface area per unit weight.

  However, the diameter of the fiber obtained by utilizing the above-described spinning technology and fiber structure manufacturing technology, and the diameter of the fiber constituting the fiber structure are the same diameter as existing fibers (several to several tens of μm). It is difficult to produce fibers with submicron or nanoscale diameters. In addition, the equipment used for extruding the fiber-forming substance under high pressure and cooling / solidifying the fiber structure is complicated and expensive, which hinders an increase in manufacturing cost and stable product supply.

  Therefore, as a new spinning technique, the “electrospinning method” exemplified in Patent Documents 1 and 2 has attracted attention. In this method, a fiber-forming substance-containing solution is charged positively or negatively, and is spun through a nozzle or a needle to a fiber structure deposition portion charged in the opposite polarity or grounded. Is the method. The fibrous fiber-forming substance spun from the nozzle or needle is refined under the influence of a potential gradient formed between the nozzle or needle and the fiber structure deposition portion. According to this method, a fiber having a diameter of several nm can be produced.

  On the other hand, studies on mass production technology, which is the subject of this method, are also being actively conducted. In Patent Document 3, a barrel that stores a liquid polymer material, a pump that pressurizes the liquid polymer material from the barrel, and a spinning device that injects the liquid polymer material supplied from the pump through a charged nozzle. A high-voltage generating unit for charging a liquid polymer substance, and a web depositing unit (collector) charged to a polarity different from that of the spinning unit is taught. According to this method, it is possible to produce a polymer web at high speed and in large quantities, unlike laboratory-scale production using a single needle provided for research purposes.

  However, according to this method, the inside of the pump is charged to a high voltage via the polymer substance, causing an electrical malfunction, and there is a high possibility that the liquid feed amount and the spinning amount will become unstable and stable. Adversely affects the production of the finished fiber structure. In addition, when using a plurality of nozzles for the purpose of obtaining a fiber structure having a uniform opening, it is necessary to provide a plurality of pumps for the purpose of stabilizing the discharge pressure and spinning amount at each nozzle. In general, pumps required for this method that require control of the amount of liquid to be supplied to a very small range are expensive, and an increase in equipment cost required for this is inevitable.

  In Patent Document 4, in an electrospinning apparatus including a polymer dope main tank, a metering pump, a nozzle block, a collector, and a power source, a dope dripping device is provided between the metering pump and the nozzle block, and the device is a sealed cylinder. An apparatus having a dope introduction tube, a gas introduction tube, a dope charge removal tube, and a hole for dropping the dope is taught. According to this method, since the charged dope is temporarily stored in a dope dropping apparatus that does not have any electrical drive unit, there is a risk that the metering pump disposed in the upper stage of the apparatus may cause an erroneous operation for the reason already described. There is no sex. Further, since a high voltage can be intermittently applied to the dope, electrostatic spinning with less energy loss is possible.

  However, in this method, gas is introduced into the apparatus in order to push out the dope into the nozzle block from within the dope dropping apparatus. Dripping is inhibited. In order to avoid this, it is necessary to increase the discharge pressure of the metering pump, but this further increases the pressure applied to the device and increases the amount of liquid to be fed. The liquid feeding amount is unsuitable for electrospinning. It is necessary to control the discharge pressure of the dope and the pressure of the gas to appropriate amounts in order to set the appropriate liquid feeding amount, but in a state where there is no pressure measuring device in the device, which is a sealed container, and extremely It is extremely difficult to control these pressures so that a very small amount of liquid is delivered.

  As described above, when the feeding of the fiber-forming substance-containing solution is unstable, the spinning of the solution at the nozzle becomes unstable, so that the thickness and openings of the resulting fiber structure are not uniform. For example, when the fiber structure is used as a filter base, the pressure loss amount becomes non-uniform, which causes a filtration failure.

US Pat. No. 6,106,913 US Pat. No. 6,110,590 JP 2002-201559 A International Publication No. 03/004735 Pamphlet

  The present invention relates to a method for stably producing a uniform fiber structure in a method for producing a fiber structure by an electrospinning method, and more specifically, in a method for producing a fiber structure of a fiber-forming substance by an electrospinning method. It is to provide.

The inventors diligently studied to solve the above-described problems, and led to the following invention.
1. In the method for producing a fiber structure of a fiber-forming substance by an electrostatic spinning method, the fiber-forming substance-containing solution is spun and at least one of the solutions connected to at least one spinning part (A) is spun. A non-condensable gas is continuously introduced into the storage tank (B) via at least one pressure control device (C), and the solution is fed to the spinning section (A) with the pressure of the gas. A method for producing a fiber structure by an electrospinning method.
2. The pressure control device (C) and the liquid level measuring device (D) disposed in the storage tank (B) are interlocked, and the gas introduced by the liquid level height of the storage tank (B). 1. Control the pressure of The method described in 1.
3. The pressure control device (C) and the thickness measuring unit (E) for measuring the thickness of the fiber structure are interlocked to control the pressure of the gas introduced by the thickness of the fiber structure. Or 2. The method described in 1.
4). The gas is air or nitrogen; ~ 3. The method in any one of.
5. The pressure of the gas is not less than atmospheric pressure and less than 1 MPa. ~ 4. The method in any one of.
6). The temperature of the gas is in the range from the freezing point to the boiling point of the solvent contained in the fiber-forming substance-containing solution. ~ 5. The method in any one of.

  By the above-described method for producing a fiber structure using an electrospinning method, it is possible to stably obtain a fiber structure of a fiber-forming substance having a uniform thickness and openings. The fiber structure thus obtained can be used, for example, as a filter base material, and can be a base material capable of capturing ultrafine particles without causing poor filtration.

The production method of the present invention will be described in detail below.
1 to 3 are schematic views of a fiber structure manufacturing process according to an embodiment of the present invention. Hereinafter, the present invention will be described in detail with reference to these drawings, but the scope of the present invention is not limited thereby.

In the production method of the present invention, in a method for producing a fiber structure of a fiber-forming substance by an electrostatic spinning method, the fiber-forming substance-containing solution is spun and connected to at least one spinning part (A). The non-condensable gas is continuously introduced into at least one storage tank (B) of the solution via at least one pressure control device (C), and the solution is spun by the pressure of the gas. Liquid is fed to (A).
First, the fiber-forming substance-containing solution is introduced into the fiber-forming substance-containing solution storage tank (B), that is, the solution storage tank 1.

  Examples of the fiber-forming substance used in the present invention include polypropylene, polyethylene, polystyrene, polyethylene oxide, polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, poly-m-phenylene terephthalate, poly-p-phenylene isophthalate, polyfluoride. Vinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene copolymer, polyvinyl chloride, polyvinylidene chloride-acrylate copolymer, polyacrylonitrile, polyacrylonitrile-methacrylate copolymer, polycarbonate, polyarylate, polyester carbonate, nylon, aramid, Examples include polycaprolactone, polylactic acid, polyglycolic acid, collagen, polyhydroxybutyric acid, polyvinyl acetate, and polypeptide Can, at least one selected from these are used, but the invention is not particularly limited thereto.

  Examples of the solvent used in the present invention include methanol, ethanol, 1-propanol, 2-propanol, hexafluoroisopropanol, tetraethylene glycol, triethylene glycol, dibenzyl alcohol, 1,3-dioxolane, 1,4-dioxane, Methyl ethyl ketone, methyl isobutyl ketone, methyl-n-hexyl ketone, methyl-n-propyl ketone, diisopropyl ketone, diisobutyl ketone, acetone, hexafluoroacetone, phenol, formic acid, methyl formate, ethyl formate, propyl formate, methyl benzoate, benzoic acid Ethyl acetate, propyl benzoate, methyl acetate, ethyl acetate, propyl acetate, dimethyl phthalate, diethyl phthalate, dipropyl phthalate, methyl chloride, ethyl chloride, methylene chloride, chloroform , O-chlorotoluene, p-chlorotoluene, chloroform, carbon tetrachloride, 1,1-dichloroethane, 1,2-dichloroethane, trichloroethane, dichloropropane, dibromoethane, dibromopropane, methyl bromide, ethyl bromide, bromide Examples include propyl, acetic acid, benzene, toluene, hexane, cyclohexane, cyclohexanone, cyclopentane, o-xylene, p-xylene, m-xylene, acetonitrile, tetrahydrofuran, N, N-dimethylformamide, pyridine, water and the like. At least one selected from these is used, but is not particularly limited thereto.

It is also possible to mix an inorganic solid material in the fiber-forming substance and the solvent described above. Examples of the inorganic solid material include oxides, carbides, nitrides, borides, silicides, fluorides, sulfides, etc., but oxides are preferably used from the viewpoint of heat resistance and workability. .
Examples of the oxide include Al ₂ O ₃ , SiO ₂ , TiO ₂ , Li ₂ O, Na ₂ O, MgO, CaO, SrO, BaO, B ₂ O ₃ , P ₂ O ₅ , SnO ₂ , ZrO ₂ , K. _{2 O, Cs 2 O, ZnO} , Sb 2 O 3, As 2 O 3, CeO 2, V 2 O 5, Cr 2 O 3, MnO, Fe 2 O 3, CoO, NiO, Y 2 O 3, Lu 2 O ₃ , Yb ₂ O ₃ , HfO ₂ , Nb ₂ O _{5 and the} like can be exemplified, and at least one selected from these can be used, but is not particularly limited thereto.

  The storage tank 1 is connected to the spinning section (A), that is, the spinning nozzle 2 via a liquid feeding pipe. The nozzle 2 is connected to the high voltage generator 3 by electrical wiring, and has a structure in which a high voltage is applied to the fiber-forming substance-containing solution fed to the nozzle 2. The solution is directed toward the counter electrode 8 installed on the back surface of the base material 7 during the transport of the base material 7 unwound from the unwinding roll 4 and taken up by the take-up roll 6 via the free roll 5. Spin out. The electrode 8 is applied with a voltage having a polarity different from the voltage applied to the nozzle 2 or grounded. By the above-described method, a fiber structure of the fiber-forming substance is obtained on the base material 7.

  The solution consumed by the nozzle 2 is continuously supplemented from the storage tank 1, and a pump capable of supplying a very small amount of liquid is often employed as the compensation method. In the liquid feeding method using a pump, since the solution is forcibly fed, it is extremely difficult to form a droplet that can be held at the tip of the nozzle 2. When the droplet formation of the solution cannot be confirmed at the tip of the nozzle 2 due to insufficient liquid feeding, the surface tension of the solution becomes excessive with respect to the electric attractive force generated in the electrostatic field. The solution is not spun. Further, when the liquid feeding becomes excessive, the liquid droplets are not held at the tip of the nozzle 2 and the liquid dripping occurs. In some cases, the liquid reaches the substrate 7 in a liquid droplet state. This also adversely affects the uniform surface properties of the thickness of the resulting fiber structure.

In addition, the above-described pump often generates unique pulsation due to the mechanism of the liquid feeding operation. Although the amount of liquid fed per unit time changes due to pulsation, the effect on the amount of spinning is enormous when handling a very small amount of spinning.
Therefore, in the present invention, a non-condensable gas is continuously introduced into the storage tank 1 through at least one pressure control device (C), that is, 10 in the figure, and the solution is supplied to the nozzle by the pressure of the gas. 2 to liquid. As the pressure control device 10, it is preferable to employ a mechanism that controls the pressure by detecting the internal pressure of the upstream of the pressure control device 10 and / or the internal pressure of the downstream of the pressure control device 10, and controls the outlet pressure by an input signal. Valves such as regulator valves and relief valves that can be used, and devices including them can be used, but are not limited thereto.

  According to the present method, the adjustment of the liquid feeding amount can be easily performed by the pressure control by the pressure control device 10, and since the liquid feeding is performed by the pressure of the gas, instability due to the pulsation of the pump described above. It is possible to eliminate unnecessary liquid feeding. In particular, when a very small amount of liquid is supplied, it is also a suitable technique to arrange a plurality of the pressure control devices 10 having different control ranges in series.

  In general, since the solution in the storage tank 1 decreases due to consumption of the solution, it is necessary to add the solution to the storage tank 1, but in the electrospinning method, the consumption amount of the solution is In this method, the amount of the solution can be stored in advance in the storage tank 1 so that the target production can be completed. When the production amount of the target fiber structure increases, the storage tank 1 can be regarded as an intermediate storage tank, and the storage tank of the solution can be further disposed on the upper stage of the storage tank 1, It is not limited.

  Moreover, in this invention, the said pressure control apparatus (C) and the liquid level height measuring apparatus (D) arrange | positioned in the said storage tank (B) are made to interlock | cooperate, and it introduce | transduces by the liquid level height of the said storage tank (B). It is preferable to control the pressure of the gas.

Although stable liquid feeding is possible by the method described above, depending on various physical properties such as the concentration and viscosity of the solution and the airtightness of the storage tank 1, the liquid head of the solution held in the storage tank 1 Such pressure may affect the amount of liquid delivered. When the liquid level of the solution in the storage tank 1 is at a high position, the pressure applied to the liquid head of the solution is large. Conversely, when the liquid level is at a low position, the pressure applied to the liquid head is small. Since the position of the liquid surface easily fluctuates due to the consumption or addition of the solution, it can be a serious problem in the present method that handles a very small amount of liquid feeding.
Therefore, in the present invention, the liquid level height measuring device (D), that is, 11 in FIG. 2 is arranged in the storage tank 1, and this is linked with the pressure control apparatus 10 described above, so that the liquid level height of the storage tank 1 is set. Thus, the pressure of the gas to be introduced is controlled.

  The liquid level height measuring device 11 may be a contact type level meter such as a capacitance type, a float type or a displacer type, or a non-ultrasonic type, a distortion type, a microwave type, a laser type, a radiation type or the like. A contact-type level meter and a device including them can be used, but are not limited thereto.

According to this method, since the influence of the pressure applied to the liquid head of the solution held in the storage tank 1 is also fed back to the pressure control device 10 described above, it is not affected by the physical properties of the solution, Stable liquid feeding becomes possible.
Moreover, in this invention, the said pressure control apparatus (C) and the thickness measurement part (E) which measures the thickness of the said fiber structure are made to interlock | cooperate, and the pressure of the said gas introduced with the thickness of the said fiber structure is controlled. It is preferable.

  The above-described method relates to stabilization of liquid feeding, that is, further homogenization of the obtained fiber structure, and in order to obtain a fiber structure having a desired thickness, within a range where stable liquid feeding and spinning are possible. The pressure of the non-condensable gas described above must be adjusted. However, when the thickness of the obtained fiber structure is measured off-line and the pressure of the gas is adjusted based on the measurement result, the desired thickness is reflected while the adjusted pressure is reflected in liquid feeding and spinning. The fiber structure which does not have this will be manufactured in large quantities, and the yield of a process will deteriorate, and, thereby, manufacturing cost will increase. In order to stably obtain a fiber structure having a desired thickness, an on-line system that does not deteriorate the process yield and enables fine adjustment of the pressure of the gas is essential.

Therefore, in the present invention, the thickness measuring device 12 for measuring the thickness of the fiber structure is disposed downstream from the spinning nozzle 2 and upstream from the take-up roll 6, and further interlocked with the pressure control device 10, thereby the fiber structure. The pressure of the gas introduced is controlled by the thickness of the gas. The thickness of the fiber structure is measured online by the thickness measuring device 12, and information regarding the thickness of the fiber structure obtained here is fed back to the pressure control device 10 described above. Generally, when the desired thickness of the fibrous structure is small, the pressure of the gas is small, and conversely, when the thickness is large, the pressure of the gas is controlled to be large.
The thickness measuring device 12 includes a contact type thickness meter such as a linear gauge, a non-contact thickness meter such as an air type, a laser type, an infrared type, a capacitance type, and an X-ray type and a device including these. Although it can employ | adopt, it is not limited to these.

According to this method, the thickness of the fiber structure is measured online, and the amount of liquid to be fed is freely changed according to the measurement result, so that the fiber structure having a desired thickness can be stably obtained. In addition, the generation of defective products and the deterioration of process yield due to pressure adjustment can be minimized.
Moreover, in this invention, it is preferable that the noncondensable gas introduce | transduced into the said storage tank 1 is air or nitrogen. Use of gases other than these may cause various problems such as partial condensation due to pressurization, dissolution in the solution, and partial reaction with the solution, making pressure control in the storage tank 1 extremely difficult. In addition, many gases other than these are expensive and risky, which is not only contrary to the gist of the present invention aimed at reducing the manufacturing cost but also has a high possibility of adversely affecting the environment.

  Therefore, in the present invention, air or nitrogen is used as the gas. Since these gases are generally used as an inert gas as a pressurizing source for various processes and instruments, it can be said that they are also suitable in this method. According to this method, the solution can be fed under pressure without adversely affecting the solution.

  In the present invention, the pressure of the gas is preferably at least atmospheric pressure and less than 1 MPa. When the inside of the storage tank 1 is less than the atmospheric pressure, the solution is no longer sent from the storage tank 1 to the nozzle 2, and when the pressure is 1 MPa or more, the pressure far exceeds the surface tension of the solution and the attractive force applied to the electrostatic field. Is applied to the solution, the solution is ejected from the nozzle 2 and a fiber structure cannot be obtained. Moreover, since it becomes high voltage | pressure, not only the structure of the liquid feeding piping provided to this, the said storage tank 1, and the said nozzle 2 will enlarge, but installation cost will increase significantly.

  Therefore, in the present invention, the pressure of the gas is set to atmospheric pressure or more and less than 1 MPa, preferably atmospheric pressure or more and less than 0.5 MPa, more preferably atmospheric pressure or more and less than 0.2 MPa. According to this method, the solution can be spun safely and stably without the solution being ejected from the nozzle 2. Moreover, it is possible to reduce the energy cost required for pressurization and the equipment cost required for processing the component parts.

Furthermore, in this invention, it is preferable to make the temperature of the said gas into the range more than the freezing point of the solvent contained in the said fiber-forming substance containing solution and below a boiling point.
When the temperature of the gas is lower than the freezing point of the solvent contained in the fiber-forming substance-containing solution, the solution is cooled and the fiber-forming substance, the coagulated solids or crystals of the solvent, etc. on the surface of the solution Therefore, clogging with these solid substances occurs in the liquid supply pipe and the nozzle 2. This not only induces uneven spinning due to fluctuations in the amount of the solution spun from the nozzle 2, but also causes damage to the storage tank 1 due to excessive pressure. In addition, even when the temperature of the gas is equal to or higher than the boiling point of the solvent, volatilization of the solvent from the solution is promoted by the introduction of the gas, so that the concentration of the solvent in the solution is reduced and the solid matter is reduced. It is likely to occur and causes the same problems as described above.

  Therefore, in the present invention, the temperature of the gas is introduced into the storage tank 1 in the range from the freezing point of the solvent to the boiling point. According to this method, no solid matter is generated in the storage tank 1, so that the pipe clogging that prevents stable production of the fiber structure does not occur. Further, there is no danger of over-pressurization due to piping blockage, and a safe fiber structure can be manufactured.

Hereinafter, the present invention will be described in detail with reference to examples, but the present invention is not limited thereto.
[Example 1]
Into a glass container (internal volume: 1000 mL) equipped with a stirrer with SUS304 anchor blade, 88 g of polyacrylonitrile is added, and 712 g of N, N-dimethylformamide (freezing point: -61 ° C., boiling point: 153 ° C.) is added. did. After sealing the open part of the container, it was stirred in a hot water bath at 70 ° C., and it was confirmed that polyacrylonitrile was uniformly dissolved in the solvent described above. The container is opened, and a total of 400 mL of the solution prepared by the above-described method is sucked up with a glass pipette with a suction rubber stopper, and this is the two solution storage tanks 1 (material: Teflon (registered trademark), contents shown in FIG. 200 ml each was put into each (300 ml), and the open portion was further sealed. Thereafter, nitrogen gas was introduced into the storage tank 1 from the gas inlet 9 via the pressure control device 10 which is a regulator valve capable of controlling the outlet pressure by an input signal. In addition, the temperature at the time of the introduction of the nitrogen gas into the pressure adjusting device 10 was 25 ° C., and the pressure was 0.2 MPa. A polyester nonwoven fabric is used as the base material 7, the roll-like base material 7 is attached to the unwinding roll 4, and is manually guided to the free roll 5 and then to the take-up roll 6. The rotational speed of the winding roll 6 was set to 2 m / min, and the drive power was turned on. Liquid feeding from the storage tank 1 to the spinning nozzle 2 (material: Teflon (registered trademark), spinning nozzle diameter: 0.3 mm, number of spinning nozzles: 6) started, and droplet dropping of the solution was confirmed at the nozzle 2 tip. At the point in time, the high-voltage generator 3 was turned on and electrostatic spinning of the solution was started. After leaving for 10 minutes, the supply of the gas, the power supply of the high voltage generator 3 and the drive power supply of the take-up roll 6 are stopped, and the roll-shaped substrate 7 and the fiber structure are removed from the take-up roll 6. It was collected. The fiber structure was peeled off from the base material 7, and 1 cm of each fiber structure was cut from 20 arbitrary locations, and the thickness of all of these was measured with an offline film thickness meter. Furthermore, all these surface states were observed with a scanning electron microscope. As a result, the thickness at each measurement location was all within ± 1.5 μm with respect to the average thickness of the fiber structure: 17 μm. Moreover, the average value of the fiber diameter in each measurement location was all within ± 100 nm with respect to the average value of the fiber diameter of all measurement locations: 331 nm.

[Example 2]
The same procedure as in Example 1 was performed except that the process illustrated in FIG. 2 using a capacitance-type non-contact level meter as the liquid level height measuring device 11 was adopted and the gas was changed to air. As a result, the thickness at each measurement location was within ± 2.0 μm for the average value of the thickness of the fiber structure: 23 μm. Moreover, the average value of the fiber diameter in each measurement location was all within ± 100 nm with respect to the average value of the fiber diameter of all measurement locations: 288 nm.

[Example 3]
It implemented similarly to Example 2 except having employ | adopted the process illustrated in FIG. 3 using the laser type non-contact thickness meter as the thickness measuring apparatus 12. FIG. As a result, the thickness at each measurement location was within ± 0.5 μm with respect to the average thickness of the fiber structure: 21 μm. Moreover, the average value of the fiber diameter in each measurement location was all within ± 100 nm with respect to the average value of the fiber diameter of all measurement locations: 309 nm.

[Example 4]
The same operation as in Example 3 was performed except that the gas was nitrogen gas at 65 ° C. and 0.5 MPa. As a result, the thickness at each measurement location was all within ± 0.5 μm with respect to the average thickness of the fiber structure: 25 μm. Moreover, the average value of the fiber diameter in each measurement location was all within ± 100 nm with respect to the average value of the fiber diameter of all measurement locations: 296 nm.

[Comparative Example 1]
The gas inlet 9 and the pressure control device 10 were removed from the manufacturing process shown in FIG. Moreover, it implemented similarly to Example 1 except having installed the tube pump between the solution storage tank 1 and the spinning nozzle 2, and sending the solution prepared by the method mentioned above with the said pump to the said nozzle 2. FIG. At this time, the amount of the solution fed was 7.8 mL / min. As a result, the thickness at each measurement location was within ± 40 μm with respect to the average thickness of the fiber structure: 59 μm. Moreover, the average value of the fiber diameter in each measurement location was all within ± 1 μm with respect to the average value of the fiber diameter in all measurement locations: 505 nm. Further, as a result of surface observation with a scanning electron microscope, spindle-shaped fiber structures confirmed when the droplets of the solution reached the substrate 7 without forming fibers were found.

[Comparative Example 2]
The same operation as in Comparative Example 1 was carried out except that the liquid feeding amount was 0.007 mL / min. As a result, the formation of the fiber structure could not be confirmed several minutes after the start of production. Clogging due to solidification of the solution could be confirmed at the tip of the spinning nozzle 2.

It is an example of the manufacturing process in the present invention, and is an example in which a pressure control device 10 is disposed between the solution storage tank 1 and the gas inlet 9. This is another example of the manufacturing process in the present invention, in which a pressure control device 10 is disposed between the solution storage tank 1 and the gas inlet 9, and a liquid level measuring device 11 is disposed in the storage tank 1. It is the other example of the manufacturing process in this invention, The pressure control apparatus 10 is measured between the said storage tank 1 and the gas inlet 9, The liquid level height measuring apparatus 11 is measured in the said storage tank 1, The thickness of a fiber structure is measured. This is an example in which a thickness measuring device 12 is provided.

Explanation of symbols

1. 1. Solution storage tank 2. Spinning nozzle 3. High voltage generator 4. Unwinding roll Freeroll 6. 6. Winding roll Base material 8. Counter electrode 9. Gas inlet 10. Pressure control device 11. Liquid level height measuring device 12. Thickness measuring device

Claims (6)

  In a method for producing a fiber structure made of a fiber-forming substance by an electrostatic spinning method, at least one solution connected to at least one spinning section (A) for spinning the fiber-forming substance-containing solution. Non-condensable gas is continuously introduced into the storage tank (B) via at least one pressure control device (C), and the solution is fed to the spinning section (A) with the pressure of the gas. A method for producing a fiber structure by an electrospinning method.   The pressure control device (C) and the liquid level measuring device (D) disposed in the storage tank (B) are interlocked, and the gas introduced by the liquid level height of the storage tank (B). The method of claim 1, wherein the pressure is controlled.   The pressure control device (C) and a thickness measuring unit (E) for measuring the thickness of the fiber structure are interlocked to control the pressure of the gas introduced by the thickness of the fiber structure. Or the method of 2.   The method according to claim 1, wherein the gas is air or nitrogen.   The method in any one of Claims 1-4 whose pressure of the said gas is more than atmospheric pressure and less than 1 MPa.   The method according to any one of claims 1 to 5, wherein the temperature of the gas is in the range from the freezing point to the boiling point of the solvent contained in the fiber-forming substance-containing solution.

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