WO2016035468A1

WO2016035468A1 - Process and device for producing nanofiber

Info

Publication number: WO2016035468A1
Application number: PCT/JP2015/070842
Authority: WO
Inventors: 小倉　徹; 片井　幸祐; 新井　利直
Original assignee: 富士フイルム株式会社
Priority date: 2014-09-04
Filing date: 2015-07-22
Publication date: 2016-03-10
Also published as: JP6170888B2; JP2016053228A

Abstract

A process and a device for producing a nanofiber are provided in which a Taylor cone is stably maintained to improve the production efficiency. A solution (25) obtained by dissolving a cellulosic polymer in a solvent is sent out from the tip of a nozzle (13) while keeping the solution at a constant temperature in the range of 5-40°C, thereby forming a Taylor cone (44) at the tip orifice (13a). A voltage is applied between the solution (25) and a collector (50) by an electric power source (62) to eject a fiber as a spinning-solution jet (45) from the Taylor cone (44) to the collector (50). A cooling gas (43) supplied through a gas supply pipe (20) and having a constant temperature in the range of 5-15°C is sent to the periphery of the Taylor cone (44) through a gas supply slit (21), which is the space between the wall of the gas supply pipe (20) and the outer peripheral surface of the nozzle (13). Due to this, the evaporation of the solvent from the Taylor cone (44) is inhibited and the occurrence of droplets due to surface solidification and resultant skin formation is inhibited. Thus, production failures caused by the droplets are eliminated.

Description

Nanofiber manufacturing method and apparatus

The present invention relates to a nanofiber manufacturing method and apparatus.

For example, a fiber (nanofiber) having a nano-order diameter of several nm or more and less than 1000 nm can be used as a material of a product such as a biofilter, a sensor, a fuel cell electrode material, a precision filter, electronic paper, or a heat pipe wick. It is possible to develop applications in various fields such as engineering and medical care.

One method for producing nanofibers is the electrospinning method (electrospinning method). The electrospinning method is performed using an electrospinning device (electrospinning device) having a nozzle, a collector, and a power source (see Patent Document 1). In this electrospinning apparatus, a voltage is applied between a nozzle and a collector by a power source, and for example, the nozzle is negatively charged and the collector is positively charged.

When a solution as a raw material is taken out from the nozzle in a state where a voltage is applied, a conical protrusion composed of a solution called a Taylor cone is formed at an opening at the tip of the nozzle (hereinafter referred to as a tip opening). When the applied voltage is gradually increased and the Coulomb force exceeds the surface tension of the solution, the solution is ejected from the tip of the Taylor cone and a spinning jet is formed. The spinning jet moves to the collector by Coulomb force and is collected as nanofibers on the collector.

When using a highly volatile solvent for the solution sent from the nozzle, the solution may solidify and clog at the opening of the tip. Moreover, when the solution solidified to some extent moves away from the opening of the tip, the solidified solution may fall on the collecting surface of the nanofibers collected on the collector. Thus, the clogging or solidification of the solution makes it impossible to reduce the quality of the product or to use it as a product. For this reason, in Patent Document 2, the cleaning means is used to remove the solidified solution by bringing the flexible member into contact with the tip opening, or to remove the solidified solution by sucking the tip opening.

In Patent Document 3, an air spraying portion is provided at a position separated from the nozzle tip opening by a predetermined distance, and air is sprayed by the air spraying portion in the traveling direction of the spinning jet to promote the movement of the spinning jet to the collector. Increasing fiber production.

JP 2005-330624 A JP 2008-202169 A JP 2014-47440 A

As shown in Patent Document 2, in the method of moving the nozzle to the cleaning station and bringing the flexible member into contact with the tip opening to remove the solidified solution, the flexible member and the nozzle are brought into contact with the tip opening by contacting the flexible member. Will bend. And when the flexible member leaves the tip opening, the deflected member or nozzle returns to its original posture, and the solidified solution adhering to the flexible member or tip opening jumps off with the momentum of returning. There are cases where stable production for a long time is difficult.

Also, in the cleaning of the tip opening by suction, in the case of a solvent that evaporates quickly, the solidified solution becomes quite hard, and thus strong suction is required. As a result, the wind flow in the spinning area (the area where spinning is performed in the spinning device) is disturbed, and the nanofibers laminated on the collector may not be uniform, and the product quality may be significantly reduced.

By the way, when a raw material such as a dilute aqueous solution of polyvinyl alcohol is used, a Taylor cone is stably formed, and the spinning jet and the flying of the fiber are also stabilized. However, in a solution having a high solvent volatilization rate, a Taylor cone cannot be formed well, and a liquid ball may be generated due to rapid evaporation of the solvent on the surface of the solution extruded from the nozzle. The liquid ball has a substantially spherical shape due to deformation of the Taylor cone, and the surface is increased in viscosity by evaporation of the solvent to form a skin, and the inside remains as a solution having a high solvent concentration. If a liquid ball is generated, it will be difficult to blow out the solution from the surface even if there is sufficient charge, and even if the spinning jet is ejected, the flight will be discontinuous and the nanofiber will be of uniform thickness It becomes difficult to form.

Also, the liquid ball may fall due to the vibration of the device. In this case, the integrated nanofiber may not be used as a product, or the quality of the nonwoven fabric may be deteriorated, for example.

As described above, in the electrospinning method of Patent Document 2, although the liquid ball is generated due to the solidification of the solution at the nozzle tip, the liquid ball is merely washed and removed symptomatically. No solution has been reached.

In the electrospinning apparatus of Patent Document 3, air is blown by an air blowing portion in the traveling direction of the spinning jet to promote the movement of the spinning jet to the collector, and the production amount of nanofibers is increased. However, the purpose is to promote the movement of the spinning jet to the collector and no consideration is given to the suppression of the liquid balls.

As described above, in the conventional electrospinning apparatus, the Taylor corn liquid balls have not been sufficiently studied. An object of this invention is to provide the nanofiber manufacturing method and apparatus which can maintain a Taylor cone stably and can improve manufacturing efficiency in view of the said problem.

In the nanofiber manufacturing method of the present invention, a solution in which a cellulosic polymer is dissolved in a solvent is sent from the tip of the nozzle as a constant temperature within a range of 5 ° C. or more and 40 ° C. or less, and a voltage is applied between the solution and the collector. A nanofiber manufacturing method in which a fiber is ejected from a solution to a collector, and a gas having a constant temperature within a range of 5 ° C. to 15 ° C. is sent to a peripheral surface of the solution sent from the tip of a nozzle. is there.

In addition, it is preferable to have a blower pipe that is arranged concentrically with the nozzle on the outside of the nozzle and in which a blower slit is formed between the nozzle and the outer peripheral surface of the nozzle, and gas is blown from the blower slit. Moreover, it is preferable that the front-end | tip of a ventilation pipe | tube protrudes rather than the front-end | tip of a nozzle, and covers the solution sent out from the nozzle by the front-end | tip part which the ventilation pipe | tube protrudes. It is preferable that the front-end | tip part which the ventilation pipe | tube protrudes has a cooling part by which a cooling medium circulates inside. The gas flow rate from the blow slit is preferably a constant flow rate in the range of 5 mm / second to 50 mm / second.

In the nanofiber manufacturing method of the present invention, a solution in which a cellulosic polymer is dissolved in a solvent is sent from the tip of the nozzle as a constant temperature within a range of 5 ° C. or more and 40 ° C. or less, and a voltage is applied between the solution and the collector. A nanofiber manufacturing method in which a fiber is jetted from a solution to a collector, the peripheral surface of the solution sent from the tip of the nozzle is covered with a cooling pipe, and the temperature of the peripheral surface of the solution is 5 ° C. It is held at a constant temperature within the following range.

The cooling pipe is arranged concentrically with the nozzle outside the nozzle, the cooling medium is circulated inside, the tip of the cooling pipe protrudes from the tip of the nozzle, and the tip of the cooling pipe protrudes from the tip of the nozzle. It is preferable to cover the solution being pumped.

The nanofiber manufacturing apparatus of the present invention sends a solution in which a cellulosic polymer is dissolved in a solvent from a tip of a nozzle as a constant temperature within a range of 5 ° C. or more and 40 ° C. or less, and applies a voltage between the solution and the collector. A nanofiber manufacturing apparatus for applying and ejecting a fiber from a solution to a collector, wherein the blower pipe is arranged concentrically with the nozzle on the outside of the nozzle and has a blower slit formed between the outer peripheral surface of the nozzle, And a cooling gas supply unit that sends a gas having a constant temperature within a range of 5 ° C. or more and 15 ° C. or less from the slit.

In addition, it is preferable that the tip of the blower tube protrudes from the tip of the nozzle, and the solution fed from the nozzle is covered with the tip of the blower tube protruding. Moreover, it is preferable that the front-end | tip part which the blast pipe protrudes has a cooling part by which a cooling medium circulates inside. The cooling gas supply unit preferably supplies the gas at a constant flow rate in the range of 5 mm / second or more and 50 mm / second or less from the blow slit.

The nanofiber manufacturing apparatus of the present invention sends a solution in which a cellulosic polymer is dissolved in a solvent from a tip of a nozzle as a constant temperature within a range of 5 ° C. or more and 40 ° C. or less, and applies a voltage between the solution and the collector. A nanofiber manufacturing apparatus that applies and jets a fiber from a solution to a collector, and has a cooling pipe arranged concentrically with the nozzle outside the nozzle and circulating a cooling medium inside, and the tip of the cooling pipe is It protrudes from the tip of the nozzle, covers the solution delivered from the nozzle by the protruding tip of the cooling tube, and maintains the temperature of the peripheral surface of the solution at a constant temperature in the range of 5 ° C to 15 ° C. is there.

According to the present invention, the solution fed from the nozzle tip can be cooled, and the evaporation rate of the solvent is suppressed. Therefore, electrospinning can be stably performed even with a solution having a high evaporation rate.

It is a side view which shows the outline of the nanofiber manufacturing apparatus of this invention. It is sectional drawing which shows the front-end | tip part of a nozzle and a blast pipe. It is sectional drawing which shows another embodiment which made the front-end | tip of the nozzle and the blast pipe the same position. It is sectional drawing which shows another embodiment which has a guide cylinder on the outer side of a ventilation pipe | tube. It is sectional drawing which shows another embodiment which has a cooling part in the front-end | tip part of a blast pipe.

As shown in FIG. 1, the nanofiber manufacturing apparatus 10 of the present invention is for manufacturing a nanofiber 46 from a solution 25 in which a cellulose polymer is dissolved in a solvent. The nanofiber manufacturing apparatus 10 includes a spinning chamber 11, a solution supply unit 12, an electrospinning nozzle (hereinafter simply referred to as a nozzle) 13, a cooling gas supply unit 14, an accumulation unit 15, and a power source 62. The spinning chamber 11 accommodates, for example, the nozzle 13, the pipe 32 of the solution supply unit 12, the cooling gas supply unit 14 and a part of the accumulation unit 15, and is configured to be hermetically sealed, so that the solvent gas leaks to the outside. To prevent that. The solvent gas is obtained by vaporizing the solvent of the solution 25.

A nozzle 13 is disposed in the upper part of the spinning chamber 11. The nozzle 13 is for discharging the solution 25 in a state of being charged negatively (−), for example, by a power source 62 as will be described later. As shown in FIG. 2, the nozzle 13 is comprised from the cylinder. A blower tube 20 is disposed outside the nozzle 13 concentrically with the nozzle 13. The blower pipe 20 has an inner diameter larger than the outer diameter of the nozzle 13 so as to form a blower slit 21 between the blower pipe 20 and the outer peripheral surface of the nozzle 13.

The nozzle 13 is made of stainless steel having an outer diameter of 0.6 mm and an inner diameter of 0.4 mm, for example, and is cut so that a tip opening edge portion 13b around the tip opening 13a is orthogonal to the cylinder center direction. The front end opening edge 13b, which is the cut surface, is polished flat.

The blower tube 20 is made of stainless steel having an outer diameter of 11 mm and an inner diameter of 10 mm, for example, and the nozzle 13 is held by a spacer (not shown) so that the tube core of the nozzle 13 and the tube core of the blower tube 20 coincide. . The material of the nozzle 13 and the blower tube 20 may be made of a conductive material such as an aluminum alloy, a copper alloy, or a titanium alloy in addition to stainless steel. For electrospinning, the solution 25 only needs to be in contact with the metal member at any location and voltage is applied. Therefore, if a voltage is applied at any place, the tip opening 13a does not necessarily need to be a conductive material.

The tip 20a of the blower tube 20 protrudes with a protruding amount L1 of, for example, about 10 mm with respect to the tip opening 13a. A tailor cone 44 made of the solution 25 sent out from the nozzle 13 is covered by the protruding tip portion 20 b of the blower pipe 20. The protrusion amount L1 is preferably changed in accordance with the sizes of the inner diameters of the nozzle 13 and the blower pipe 20. The protrusion amount L1 covers the Taylor cone 44 and is maintained at a constant temperature by the cooling gas 43. It is preferable that

As shown in FIG. 1, a pipe 32 of the solution supply unit 12 is connected to the base end of the nozzle 13. The solution supply unit 12 is for supplying the solution 25 to the nozzle 13 of the spinning chamber 11. The solution supply unit 12 includes a storage container 30, a pump 31, and a pipe 32. The storage container 30 stores the solution 25 as a constant temperature within a range of 5 ° C. or higher and 40 ° C. or lower. Thereby, the temperature of the solution 25 which comes out of the nozzle 13 is made into the range of 5 to 40 degreeC. If it is less than 5 degreeC, since a water | moisture content mixes by the dew condensation in the storage container 30, it is not preferable. Moreover, when it exceeds 40 degreeC, it will become difficult to suppress evaporation of the solvent in the solution 25, and it is not preferable.

The pump 31 sends the solution 25 to the nozzle 13 via the pipe 32. By changing the number of rotations of the pump 31, the flow rate of the solution 25 delivered from the nozzle 13 can be adjusted. In the present embodiment, the flow rate of the solution 25 is 4 cm ³ / hour, but the flow rate is not limited to this. When the solution 25 is sent to the nozzle 13 by the pump 31, as shown in FIG. 2, a substantially conical Taylor cone 44 is formed by the solution 25 at the tip opening 13 a of the nozzle 13. In addition, although the solution supply part 12 which consists of the storage container 30 and the pump 31 is used, when the solution 25 supplied to the nozzle 13 is a small amount, a syringe (not shown) may be used.

As shown in FIG. 1, a pipe 38 of the cooling gas supply unit 14 is connected to the proximal end of the blower pipe 20. The cooling gas supply unit 14 includes a blower 35, a flow rate adjustment valve 36, a cooler 37, and a pipe 38. The blower 35 compresses air. In addition, although air is used as the cooling gas 43, an inert gas such as carbon dioxide gas may be used. When an inert gas is used, an inert gas supply source is connected instead of the blower 35. The cooler 37 which is a part of the cooling gas supply unit 14 is disposed in the spinning chamber 11, but may be disposed outside the spinning chamber 11.

The flow rate adjusting valve 36 adjusts the feed amount of the cooling gas 43 from the blow slit 21 of the blow pipe 20. By adjusting the feed amount, the flow rate of the cooling gas 43 from the blow slit 21 to the outer peripheral surface of the solution 25 is set to a constant flow rate within a range of 5 mm / second to 50 mm / second. By setting the flow rate of the cooling gas 43 within the range of 5 mm / second or more and 50 mm / second or less, the Taylor cone 44 can be wrapped with the cooling gas 43 and cooled. In addition, when the speed of the cooling gas 43 is 5 mm / second or more, the periphery of the Taylor cone 44 can be reliably cooled compared to less than 5 mm / second, and generation of liquid balls can be suppressed. Further, instability in the spinning direction of the spinning jet 45 and uneven distribution due to a part of the surface of the Taylor cone 44 becoming hard can be suppressed. When the speed of the cooling gas 43 is 50 mm / second or less, the supercooling to the spinning jet 45 flying from the Taylor cone 44 is suppressed as compared with the case where the cooling gas 43 exceeds 50 mm / second, and evaporation of the solvent from the spinning jet 45 is suppressed. The nanofiber 46 can be obtained reliably without being obstructed.

The cooler 37 cools the air that has passed through the flow rate adjusting valve 36 to a constant temperature within a range of 5 ° C. to 15 ° C. As the cooler 37, one using a cooling medium or one using various other cooling methods can be used. Below 5 ° C., depending on the temperature and humidity conditions in the spinning area, moisture contained in the gas phase (atmosphere gas in the apparatus = usually air) in the spinning area is partially condensed in the solution 25 discharged from the nozzle 13, and spinning is performed. Becomes unstable. When it exceeds 15 degreeC, the liquid-ball suppression effect by cooling will fall.

The accumulation unit 15 is disposed below the nozzle 13. The stacking unit 15 includes a collector 50, a collector rotating unit 51, a support body supply unit 52, and a support body winding unit 53. The collector 50 is for collecting the solution 25 delivered from the nozzle 13 as nanofibers 46. The collector 50 is made of an endless belt made of a strip-shaped metal, for example, stainless steel. The collector 50 is not limited to stainless steel, and may be formed of a material that is charged by application of a voltage from the power source 62. The collector rotating unit 51 is composed of a pair of

rollers

55 and 56, a motor 57, and the like. The collector 50 is stretched horizontally around a pair of

rollers

55 and 56. A motor 57 disposed outside the spinning chamber 11 is connected to the shaft of one roller 55 and rotates the roller 55 at a predetermined speed. By this rotation, the collector 50 circulates and moves between the pair of

rollers

55 and 56. In this embodiment, the moving speed of the collector 50 is 10 cm / hour, but is not limited to this.

The support body 60 made of a strip-shaped aluminum sheet is supplied to the collector 50 by the support body supply section 52. The support body 60 in the present embodiment has a thickness of approximately 25 μm. The support 60 is for collecting the nanofibers 46 and obtaining the nanofiber layers (nonwoven fabrics) 47. The support body 60 on the collector 50 is wound up by the support body winding part 53. The support body supply unit 52 has a delivery shaft 52a. A support roll 54 is attached to the delivery shaft 52a. The support roll 54 is configured by winding the support 60. The support winding portion 53 has a winding shaft 58. The winding shaft 58 is rotated by a motor (not shown), and the support body 60 on which the nanofiber layer 47 is formed is wound around the core 61 to be set. As described above, the nanofiber manufacturing apparatus 10 has a function of manufacturing a nonwoven fabric composed of the nanofiber layer 47 in addition to a function of manufacturing the nanofiber 46, and a nanofiber manufacturing method by an electrospinning method is performed. The moving speed of the collector 50 and the moving speed of the support 60 are preferably the same so that friction does not occur between them. Note that the support 60 may be placed on the collector 50 and moved by the movement of the collector 50. Further, the support 60 may be interlocked with the collector 50 by applying a winding tension to the support 60.

The power source 62 applies a voltage of, for example, 30 kV between the nozzle 13 and the collector 50 to charge the nozzle 13 to minus (−) and charge the collector 50 to plus (+). Due to this charging, a spinning jet 45 is ejected from the Taylor cone 44 formed in the tip opening 13 a toward the collector 50. Note that the polarity of charging may be reversed. The distance L2 between the tip of the nozzle 13 and the collector 50 varies depending on the type of polymer and solvent, the mass ratio of the solvent in the solution 25, etc., but is preferably in the range of 30 mm to 300 mm. In this embodiment, the distance L2 is 170 mm. Yes. Since the distance L2 is 30 mm or more, the spun jet 45 to be ejected is more reliably split by repulsion due to its own charge before reaching the collector 50, compared to a case where the distance L2 is shorter than 30 mm. The nanofiber 46 can be obtained more reliably. Since the solvent evaporates more reliably by splitting in this way, a sticky nonwoven fabric can be more reliably prevented. Moreover, when the distance L2 is 300 mm or less, the applied voltage can be kept low compared with the case where the distance L2 exceeds 300 mm and is too long. Therefore, since the insulation of the apparatus is more reliably prevented from being broken by the application of a high voltage, the apparatus is not damaged due to an unintended short circuit.

The thickness of the obtained nanofiber 46 varies depending on the magnitude of the voltage applied to the nozzle 13 and the collector 50. From the viewpoint of forming a thin fiber, it is preferable that the voltage is as low as possible. However, if it is lowered too much, it may not be in the form of a fiber but may become a ball and adhere to the collector 50 in some cases. On the contrary, if the voltage is increased, the fiber becomes thicker. If the voltage is increased too much, the insulation of the device may be broken and the device may be damaged due to electric leakage from an unexpected place. Therefore, the voltage applied to the nozzle 13 and the collector 50 is preferably 2 kV or more and 40 kV or less.

As the cellulose-based polymer, cellulose triacetate (TAC) is used in the present embodiment, but is not limited to this. Cellulose diacetate (DAC), cellulose propionate, cellulose butyrate, cellulose acetate propionate, nitro It may be at least one of cellulose, ethyl cellulose, carboxymethyl ethyl cellulose, or a mixture thereof.

Solvents for dissolving the cellulose polymer include methanol, ethanol, isopropanol, butanol, benzyl alcohol, acetone, methyl ethyl ketone, cyclohexanone, methyl acetate, ethyl acetate, propyl acetate, butyl acetate, methyl formate, ethyl formate, hexane, cyclohexane, dichloromethane Chloroform, carbon tetrachloride, benzene, toluene, xylene, dimethylformamide, N-methylpyrrolidone (NMP), diethyl ether, dioxane, tetrahydrofuran, 1-methoxy-2-propanol and the like. These may be used alone or in combination depending on the type of cellulosic polymer. When the solvent is used alone, the formation of liquid balls becomes prominent when the boiling point of the solvent is about 50 ° C. or lower. In addition, a solvent having a low boiling point tends to form a liquid ball because the evaporation rate of the solvent is high. In order to suppress this, it is preferable to adjust the evaporation rate of the solvent by mixing a solvent having a high boiling point. In the present embodiment, a mixture of dichloromethane and NMP is used as the solvent.

Generally, in a polymer solution, the viscosity often changes greatly as the temperature decreases. In the present embodiment, since the concentration of the solution 25 is sufficiently dilute at 2% by mass or more and 10% by mass or less, the solution viscosity is low, and the effect of suppressing the solvent evaporation by the cooling gas 43 appears remarkably.

Next, the operation of this embodiment will be described. In FIG. 1, a voltage is applied by a power source 62 to the nozzle 13 and the collector 50 that circulates and moves. The cooling gas supply part 14 is operated and the cooling gas 43 is sent from the ventilation slit 21 of the nozzle 13 (refer FIG. 2). The collector 15 and the support 60 are moved by operating the stacking unit 15. When the solution supply unit 12 is operated and the solution 25 is sent out from the tip opening 13a of the nozzle 13 as shown in FIG. 2, a Taylor cone 44 is formed in the tip opening 13a. The collector 50, which is positively charged by the application of voltage, attracts the solution 25 sent from the tip opening 16b in a negatively charged state, and the spinning jet 45 is ejected toward the collector 50. The negatively charged spinning jet 45 splits into a smaller diameter due to repulsion due to its own charge while traveling toward the collector 50, and is collected as a nanofiber 46 on the support 60. The collected nanofibers 46 are sent to the support winding portion 53 together with the support 60 as a nanofiber layer 47. The nanofiber layer 47 is wound around the core 61 in a state where the nanofiber layer 47 overlaps the support 60.

After the core 61 is removed from the winding shaft 58, the nanofiber layer 47 is separated from the support 60. Thereafter, the nanofiber layer 47 is cut into a desired size, and a nonwoven fabric made of the nanofibers 46 is obtained.

In the present embodiment, as shown in FIG. 2, the cooling gas 43 is sent out from the blowing slit 21 between the blowing pipe 20 and the nozzle 13, and the cooling gas 43 covers the Taylor cone 44 at the tip of the nozzle 13, so that the solution The evaporation rate of 25 solvents is suppressed. Thereby, the surface of the Taylor cone 44 does not become hard, and generation | occurrence | production of a liquid ball is suppressed. Therefore, the problem that it becomes difficult to form the nanofiber 46 having a uniform thickness due to the generation of the liquid ball and the problem of the generation of defective products due to the drop of the liquid ball are solved. Thus, electrospinning can be performed stably even with a solution having a high evaporation rate.

In the said 1st Embodiment, although the front-end | tip 20a of the ventilation pipe | tube 20 protruded with respect to the front-end | tip opening 13a of the nozzle 13, the tailor cone 44 of the front-end | tip opening 13a was covered with the ventilation pipe | tube 20, FIG. As in the second embodiment, the tip 71a of the blower pipe 71 may be positioned in accordance with the tip 70a of the nozzle 70. In this case, since the tip 70a of the nozzle 70 is not hidden in the tip 71b of the blower pipe 71 as in the first embodiment, the tip 70a can be easily cleaned. In each embodiment, the same constituent members are denoted by the same reference numerals, and redundant description is omitted.

As shown in FIG. 4, in the third embodiment of the present invention, a guide tube 75 is attached to the distal end portion 71b of the blower tube 71 of the second embodiment so as to be movable in the cylinder center direction. In the case of this third embodiment, at the guide position where the guide tube 75 is lowered (see FIG. 4), the cooling gas 43 from the blow slit 21 covers the Taylor cone 44 by the guide tube 75 and the blow tube 71. The Taylor cone 44 can be reliably cooled by the cooling gas 43. In cleaning, the tip 70a of the nozzle 70 can be exposed by sliding the guide tube 75 upward from the guide position to the retracted position. For this reason, the tip opening 13a of the nozzle 13 can be reliably cleaned. The guide tube 75 may be biased so as to protrude toward the tip by a spring (not shown) or the like, and may be positioned at a protruding position and a retracted position by a click mechanism (not shown).

In the fourth embodiment shown in FIG. 5, a cooling portion 81 in which a cooling medium 80 is circulated is provided at the tip 20b of the blower tube 20 of the first embodiment. In this case, the Taylor cone 44 can be cooled by the cooling unit 81 of the blow pipe 20 in addition to the cooling gas 43. Therefore, the evaporation rate of the solvent in the Taylor cone 44 can be further suppressed, and the generation of liquid balls can be suppressed.

In the fifth embodiment, the air from the air duct 20 of the fourth embodiment is eliminated, and the Taylor cone 44 is cooled by the cooling unit 81 of the air duct 20. As described above, even when the blower pipe 20 is used as a cooling pipe, the Taylor cone 44 can be cooled, and generation of liquid balls can be suppressed. In addition, although not shown in the drawing, the cooling pipe having the cooling unit 81 may be used at the tip 20b. The cooling unit 81 of the cooling pipe may use various cooling devices having a cooling function in addition to the cooling medium 80 that is circulated and cooled.

In each of the above embodiments, the description has been made assuming that only one nozzle 13 or 70 is provided, but a plurality of nozzles 13 or 70 may be used. When a plurality of nozzles are used, it is preferable to provide a plurality of nozzles 13 and 70 in a direction perpendicular to the feeding direction of the support 60. Further, the nozzles 13 and 70 may be arranged in a matrix in the feeding direction of the support 60 and in a direction orthogonal to the feeding direction. By making the nozzles 13 and 70 plural, the area of the obtained nanofiber layer 47 can be increased, and the production efficiency can be increased. In addition, when the number of nozzles 13 and 70 increases and the total solution discharge amount from the nozzles 13 and 70 increases, it is preferable to provide a solvent recovery unit (not shown) in the spinning chamber 11.

In the above embodiment, the cross-sectional shape of the nozzles 13 and 70 is circular, but it may be a long and narrow rectangular slit not shown. In this case, the blower slit is similarly formed into an elongated slit shape in accordance with the sectional shape of the nozzle.

Next, an example for confirming the effect of the present invention will be described. In Example 1, a solution 25 in which cellulose triacetate was dissolved in a mixed solvent was used. For the mixed solvent, the mixing ratio (mass) of dichloromethane and NMP was dichloromethane: NMP = 8: 2, and the concentration of the cellulose triacetate solution was 4 mass%.

The nozzle 13 used was a single stainless steel cylindrical tube having an inner diameter of 0.4 mm and an outer diameter of 0.6 mm. The tip opening edge 13b was cut horizontally, and then the cut surface was polished. The blower tube 20 having an inner diameter of 10 mm and an outer diameter of 11 mm was concentric with the nozzle 13, the tip of the blower tube 20 was projected from the tip opening edge 13 b, and the projection amount L 1 at this time was 10 mm.

An aluminum sheet having a thickness of about 25 μm was set as the support 60 on the collector 50, and the distance L2 from the nozzle 13 to the collector 50 was set to 170 mm. The collector 50 was moved at a speed of 100 mm / hour. The support 60 on the collector 50 was also moved at the same speed as the collector 50 was moved.

Air was used as the cooling gas 43 from the blower tube 20, and the air was cooled to 10 ° C. and sent out from the blower slit 21 at 20 mm / second. A voltage of 35 kV was applied between the nozzle 13 and the collector 50, the nozzle 13 was charged negatively, and the collector 50 was charged positively. The solution 25 was supplied to the nozzle 13 at a speed of 4 cm ³ / hour, and a sample of A4 size was collected.

Example 2 was the same as Example 1 except that the nozzle 13 shown in FIG. 3 was used instead of the nozzle 13 of Example 1. The third embodiment is the same as the first embodiment except that the tailor cone 44 is maintained at 10 ° C. without using the blower pipe 20 having the cooling unit 81 in which the cooling medium 80 is circulated in the interior shown in FIG. Condition.

Comparative Example 1 was the same as Example 1 except that the cooling gas 43 was not supplied from the blower tube 20 in Example 1. In Comparative Example 2, the same conditions as in Example 1 were used except that the cooling gas 43 was supplied from the blower pipe 20 at 100 mm / second in Example 1. In Comparative Example 3, the same conditions as in Example 1 were used except that the cooling gas 43 was supplied at room temperature (25 ° C.) without being cooled.

The number of clogged nozzles and the number of drops of liquid balls (solidified solution) before taking A4 size samples were measured, and the examples and comparative examples were evaluated. When the nozzle is clogged, there are a case where spinning can be resumed by removing the solidified portion at the tip of the nozzle and a case where removal is not completely eliminated even if the solidified portion is removed, and resumption is impossible. If resumable, spinning continued. If it was impossible to resume, spinning was interrupted. When a sample of A4 size was able to be collected, it was determined to be acceptable, and when a sample could not be collected due to interruption, it was determined to be unacceptable.

In Examples 1 and 3, the number of nozzle clogging and the number of drops of liquid balls were both 0, which was acceptable. In Example 2, the number of drops of the liquid ball was 1, and the sample defect was minor and passed. On the other hand, in Comparative Example 1, the number of clogged nozzles was 3, the number of drops of the liquid ball was 13, and the spinning was interrupted, so it was rejected. Further, in Comparative Example 2, the number of nozzle cloggings was 2, the number of drops of liquid balls was 19, and the spinning was interrupted, so it was rejected. In Comparative Example 3, the number of clogged nozzles was 5, the number of dropped liquid balls was 17, and the spinning was interrupted, so it was unacceptable. Thus, in the present invention, there is almost no nozzle clogging or drop of liquid balls, and spinning can be performed smoothly.

DESCRIPTION OF SYMBOLS 10 Nanofiber manufacturing apparatus 12 Solution supply part 13 Nozzle 13a Tip opening 13b Tip opening edge part 14 Cooling gas supply part 15 Accumulation part 20 Air blower 20a Tip 20b Tip part 21 Air blow slit 25 Solution 43 Cooling gas 44 Taylor cone 45 Spinning jet 46 Fiber 47 Nanofiber layer 50 Collector 62 Power supply 70 Nozzle 71 Blower pipe 75 Guide pipe 80 Cooling medium 81 Cooling section

Claims

A solution in which the cellulosic polymer is dissolved in the solvent is sent out from the tip of the nozzle as a constant temperature in the range of 5 ° C. or more and 40 ° C. or less, and a voltage is applied between the solution and the collector to remove the solution from the solution. In a nanofiber manufacturing method for ejecting a fiber to a collector,
The nanofiber manufacturing method which sends the gas of the constant temperature in the range of 5 to 15 degreeC to the surrounding surface of the said solution sent out from the front-end | tip of the said nozzle.
2. The nanofiber according to claim 1, further comprising a blower pipe that is concentrically arranged on the outside of the nozzle and has a blower slit formed between the nozzle and an outer peripheral surface of the nozzle, and the gas is blown from the blower slit. Production method.
The nanofiber manufacturing method according to claim 2, wherein a tip of the blower tube protrudes from a tip of the nozzle, and the solution fed from the nozzle is covered by a tip of the blower tube protruding.
4. The nanofiber manufacturing method according to claim 3, wherein the projecting tip of the air duct has a cooling part in which a cooling medium is circulated.
The method of manufacturing a nanofiber according to any one of claims 2 to 4, wherein a flow rate of the gas from the blow slit is a constant flow rate in a range of 5 mm / second to 50 mm / second.
A solution in which the cellulosic polymer is dissolved in the solvent is sent out from the tip of the nozzle as a constant temperature in the range of 5 ° C. or more and 40 ° C. or less, and a voltage is applied between the solution and the collector to remove the solution from the solution. In a nanofiber manufacturing method for ejecting a fiber to a collector,
A method for producing nanofibers, wherein the peripheral surface of the solution fed from the tip of the nozzle is covered with a cooling pipe, and the temperature of the peripheral surface of the solution is maintained at a constant temperature within a range of 5 ° C to 15 ° C.
The cooling pipe is arranged concentrically with the nozzle outside the nozzle, a cooling medium is circulated therein, a tip of the cooling pipe protrudes from a tip of the nozzle, and a tip of the cooling pipe protrudes. The nanofiber manufacturing method according to claim 6, wherein the solution fed from the tip of the nozzle is covered.
A solution in which the cellulosic polymer is dissolved in the solvent is sent out from the tip of the nozzle as a constant temperature in the range of 5 ° C. or more and 40 ° C. or less, and a voltage is applied between the solution and the collector to remove the solution from the solution. In the nanofiber manufacturing equipment that ejects the fiber to the collector,
A blower pipe having a blower slit formed concentrically with the nozzle on the outside of the nozzle and formed between the outer peripheral surface of the nozzle;
A nanofiber manufacturing apparatus comprising: a cooling gas supply unit configured to send a gas having a constant temperature within a range of 5 ° C. to 15 ° C. from the blow slit.
9. The nanofiber manufacturing apparatus according to claim 8, wherein a tip of the blower tube protrudes from a tip of the nozzle, and the solution fed from the nozzle is covered by a protruding tip of the blower tube.
10. The nanofiber manufacturing apparatus according to claim 9, wherein the projecting tip of the air duct has a cooling part in which a cooling medium is circulated.
11. The nanofiber manufacturing apparatus according to claim 8, wherein the cooling gas supply unit supplies the gas at a constant flow rate in a range of 5 mm / second to 50 mm / second from the air blowing slit. .
A solution in which the cellulosic polymer is dissolved in the solvent is sent out from the tip of the nozzle as a constant temperature in the range of 5 ° C. or more and 40 ° C. or less, and a voltage is applied between the solution and the collector to remove the solution from the solution. In the nanofiber manufacturing equipment that ejects the fiber to the collector,
A cooling pipe that is arranged concentrically with the nozzle outside the nozzle and in which a cooling medium is circulated;
The tip of the cooling tube protrudes from the tip of the nozzle, the tip of the cooling tube protrudes to cover the solution fed from the nozzle, and the temperature of the peripheral surface of the solution is 5 ° C. or more and 15 ° C. or less. Nanofiber manufacturing equipment that maintains a constant temperature within the range of.