JP4862665B2 - Nozzle for polymer fiber production - Google Patents

Description

The present invention relates to a nozzle for producing a polymer fiber and a polymer fiber producing apparatus using the same, and is suitable, for example, for producing a large amount of a porous polymer web. or a centrifugal force is accompanied thereto, but relates to the nozzle for generating polymer fibers to electronic spun as a polymer fiber.

  In order to spin a polymer melt or solution as a material, a charge-induced spinning method (electrospinning method) or an electrospinning method (for example, Patent Literature 1, 2) is already known. In the electrospinning method, a polymer solution that is supplied linearly to a nozzle or capillary and is discharged linearly is charged through a nozzle or the like, and the distance between charged charges decreases as the solvent of the polymer solution evaporates. When the acting Coulomb force increases and the Coulomb force overcomes the surface tension of the linear polymer solution, a phenomenon that the linear polymer solution is stretched explosively is obtained. A phenomenon called “primary”, “secondary” and “tertiary” is repeated to create a polymer fiber having a sub-micron diameter, so-called nanofiber. In recent years, polymer fibers and fine polymer particles or powders are obtained by electrospinning in the form of spray instead of fibers.

Further, the intervals between the plurality of fluid separation portions on the side where the liquid for preventing electrons flows out with charging are integrated to less than 1 mm, and the fluid supplied from the plurality of fluid separation portions is made into fibers by charge induction on the receiving side. A technology that enables high-efficiency production of polymer fibers by receiving them is already known (see, for example, Patent Document 3). Further, Patent Document 3 states that it is desirable that the shape of the fluid detachment portion is convex, in addition to limiting the distance between the fluid detachment portion and the receiving side to an extremely small range of 0.1 cm to 5 cm. As an example, mentioning 50 mm and 250 mm long capillaries made of stainless steel, enumeration of various three-dimensional forms, flat plate forms, and various forms using polyethylene, etc. The fluid can be guided to the tip by surface tension, gravity, stretching tension, etc., and a groove can be formed in each fluid separation site to make the fluid easy to pass. The fluid may ooze out from the inside, or a combination of these may be used. Furthermore, two of these two-dimensional flat plates are used in parallel, and the gap can be used as a fluid flow path. Also, an isosceles triangle film with a thickness of 0.5 mm or less is attached to the capillary tip, and the surface tension There is also a method of guiding the fluid to the apex of the triangle. The base of the isosceles triangle is preferably 100 microns or less, and the tip angle is preferably 60 to 120 °.
JP 2002-201559 A JP 2006-507428 A JP 2006-152479 A

  By the way, the present inventor has been developing so that a large amount of nanofibers can be produced by spraying a polymer solution through the nozzle, and the nozzle is made dense like the fluid separation part disclosed in Patent Document 3. Arranging is certainly effective. However, how efficiently a polymer fiber can be produced with one nozzle greatly affects the production efficiency. From the development experience of the present inventor, it has been found that the outflow efficiency of the polymer liquid from the nozzle and the concentration of the charge at the nozzle opening through which the polymer liquid flows out are important factors. The magnitude and clogging of the resistance of the polymer solution passing through the nozzle affect the outflow efficiency, and if the nozzle opening is large, the generated polymer fiber is difficult to be thinned. In addition, if the concentration ratio of the charge at the opening is low, the charge rate of the polymer liquid flowing out from the nozzle opening is low, and the effect of stretching due to electrostatic explosion, the dispersion of the polymer fiber formed by the flowing polymer liquid is weakened by the charge induction effect. And stretchability are reduced. When the length is as long as 50 mm or 250 mm as in a metal capillary as described in Patent Document 3, the concentration ratio of charges to the opening through which the polymer solution flows out increases, but the outflow resistance of the polymer solution is large and clogging occurs. Productivity is low. In addition, if the resin nozzle described in Patent Document 3 is used, the concentration of electric charge on the opening cannot be expected, and if the nozzle length is shortened to 3 mm or less, the outflow efficiency of the polymer liquid is increased. Even when the same voltage as that exceeding 3 mm is applied, the amount of polymer fiber that can be generated is reduced, and in this case, productivity is not increased. In addition, in the method of exuding the polymer solution described in Patent Document 3, the outflow efficiency is significantly reduced.

An object of the present invention is to provide a Nozzle suitable polymeric fiber product to produce a large amount of the polymer fiber.

In order to achieve the above-described object, the present invention provides a polymer fiber producing method in which a polymer liquid is caused to flow out of a small hole accompanied by charging with a high voltage, and a polymer fiber is produced at least with stretching due to electrostatic explosion. A nozzle having a conductive portion for forming at least an outer surface layer from a high voltage application portion on the base side to a small hole opening, and charging the polymer liquid flowing out from the small hole to a high voltage. The outer surface formed is narrow from the high voltage application portion toward the small hole opening satisfying a predetermined applied voltage concentration distance, and the small hole opening serves as a charge concentration portion.

  According to such a feature, the high-voltage application unit of the nozzle is used to cause the polymer liquid to flow out of the small hole of the nozzle with charging by a high voltage and to generate a polymer fiber at least with stretching by electrostatic explosion. From the high-voltage application part to the small hole opening, the opening is made as a charge concentrating part that tends to concentrate the electric charge. , The concentration of charge at the aperture of the small hole is realized at a relatively short applied voltage concentration distance, and the charging effect on the flowing polymer solution is enhanced, and the applied voltage concentration distance from the nozzle of the polymer solution can be shortened as much as possible. Outflow resistance can be reduced. Further, if necessary, the outer surface layer of the nozzle can be made of a conductive material, and the inner surface layer can be made of a different material having a better releasability from the polymer liquid than the conductive material.

  Furthermore, the charge concentrating portion is characterized in that it has a projecting piece extending in at least one circumferential direction around the small hole opening in the outflow direction of the polymer solution.

According to this feature, the protrusion extending from the charge concentration unit formed by opening Roh nozzle, without particularly increasing the outflow resistance of the polymer solution without done the closure, therefore, is not a cause of clogging, The chargeability of the polymer solution flowing out by extending the charge concentration portion of the opening can be enhanced.

  According to the nozzle for producing the polymer fiber of the present invention, the polymer liquid is discharged from the small hole of the nozzle with charging with a high voltage, and at least with stretching due to electrostatic explosion, the polymer fiber is produced. While realizing the stable outflow without clogging by shortening the applied voltage concentration distance from the high voltage applying part to the opening of the small hole by taking advantage of the electric charge transfer property due to conductivity to reduce the outflow resistance of the polymer liquid Because the polymer liquid that flows out with the opening as a charge concentration part can be charged efficiently due to the narrow shape toward the opening, the amount of polymer fiber generated and stretched using electrostatic explosion that is strong and often collected repeatedly , And further, stretchability and flight distance by charge induction can be improved.

  Hereinafter, a polymer fiber generating nozzle and a polymer fiber generating apparatus using the same according to an embodiment of the present invention will be described with reference to FIGS. 1 to 8 for the understanding of the present invention.

  As shown in FIG. 1 (a), a nozzle 1 for producing a polymer fiber is provided in an electrospinning system such as a container 2, and a high voltage V1 of about 1 KV to 100 KV, for example, is applied from a high voltage generator 3 to the container 1. The polymer liquid 4 in 2 is discharged from the small hole 5 with charging, and a polymer fiber generating device 10 is formed that generates a polymer fiber with stretching at least by electrostatic explosion.

  Here, the polymer liquid 4 is a variety of polymers as known in Patent Documents 1 and 2, such as petroleum-based polymers such as polyvinylidene fluoride (FVDF), polyvinylidene fluoride-co-hexafluoropropylene, and polyacrylonitrile. A variety of polymers are applicable, including polymers such as copolymers and mixtures thereof melted or dissolved in any solvent.

  The nozzle 1 of the present embodiment includes the case where the whole is made of a conductive material in common, such as the example shown in FIG. 1, the example shown in FIG. 2, the example shown in FIG. 3, and the example shown in FIG. A main body having a conductive portion for charging the polymer liquid 4 flowing out from the small hole 5 to a high voltage is formed from at least the outer surface layer from the high voltage applying unit 1b on the base 1a side to the opening 1c of the small hole 5. The outer surface formed by the conductive portion is narrowed from the high voltage application portion 1b toward the opening 1c of the small hole 5 to satisfy a predetermined applied voltage concentration distance L, and the opening 1c of the small hole 5 is used as the charge concentration portion. Has a basic configuration. As a result, the polymer solution 4 flows out from the small hole 5 of the nozzle 1 with charging by a high voltage, and a polymer fiber is generated at least with stretching by electrostatic explosion. From the high voltage application part 1b to the opening part 1c of the small hole 5, the opening part 1c tends to concentrate the electric charge. As a result, the concentration of charges on the opening 1c of the small hole 5 is realized at a relatively short applied voltage concentration distance L, and the charging effect on the polymer liquid 4 flowing out is enhanced. The outflow resistance of the polymer solution 4 from the nozzle 1 can be reduced by the amount that can be shortened.

  As a result, the applied voltage concentration distance L from the high voltage application portion 1b utilizing the electric charge transferability due to the conductivity to the opening portion 1c of the small hole 5 is shortened to reduce the outflow resistance of the polymer solution 4 and to prevent clogging. The polymer liquid 4 that flows out with the opening 1c as a charge concentrating portion can be efficiently charged by the shape narrowed toward the opening 1c while realizing a stable and stable outflow. The amount of polymer fiber used, stretchability, and the polymer fiber generator 10 is used to charge the collector 7 to a high voltage V2 having a polarity opposite to that of the nozzle 1 or as shown in FIG. The stretchability and the flight distance can be improved by charge induction by using the polymer upper production apparatus 20 connected to. Therefore, the produced polymer fiber is collected to form a porous polymer web, which is suitable for increasing the porosity and the density and improving the productivity. The collecting body 7 may be stopped or a moving body such as a conveyor.

  The tapered shape of the nozzle 1 from the high voltage application portion 1b toward the small hole opening portion 1c is a circular taper shape, but is not limited thereto. For example, the tapered surface in the figure can be a concave elliptical surface or a convex elliptical surface.

  Moreover, although the brass etc. are employ | adopted as an electroconductive material, it is not restricted to this. In the nozzle 1 in which the conductive material is a partial example, the outer surface layer of the nozzle 1 may be a conductive material, and the inner surface layer may be made of a different material having better releasability from the polymer liquid than the conductive material, if necessary. In the case where the whole is made of a conductive member, it can be easily manufactured as a single unit and the cost can be reduced.

  Furthermore, it has a clogging relief shape in which the passage cross-sectional area A2 of the polymer liquid supply passage 6 connected to the back of the small hole 5 is larger than the opening area A1 of the small hole 5. Thereby, the opening area A1 of the small hole 5 is made small enough to generate a polymer fiber having a predetermined thinness such as a nano unit, and the polymer liquid supply path 6 at the back connected to the small hole 5 is opened to the small hole 5. The clogging relief shape having a larger passage cross-sectional area A2 than the area A1 is formed, the outflow resistance of the polymer liquid 4 toward the small holes 5 is reduced, and the small holes 5 can flow out without clogging. For this purpose, it is more advantageous to make the length L1 of the small hole 5 smaller as shown in FIG. 2A than to increase the length L1 as shown in FIG. 1A, as shown in FIG. Thus, it is more preferable to set the length L1 to zero.

  The clogging relief shape of the polymer liquid supply path 6 is a shape in which the passage cross-sectional area increases from the inner opening of the small hole 5 toward the back portion, and the step portion is formed while the passage cross-sectional area gradually decreases toward the small hole 5. The polymer liquid 4 that is connected to the small hole 5 and flows out through the nozzle 1 is smoothly flowed out of the small hole 5. More specifically, the clogging relief shape is a circular tapered surface. However, it is not limited to this. For example, the illustrated tapered surface can be a concave ellipsoid or a convex ellipsoid.

  In the example shown in FIG. 4, the small hole opening 1 c forming the charge concentrating portion is in particular the flow direction of the polymer solution 4 from at least one circumferential direction around the small hole 5, that is, the front on the axis of the nozzle 1. It is assumed to have a protruding piece 1d extending in the direction. In this way, the projecting piece 1d extending from the charge concentration portion formed by the opening 1c of the nozzle 1 does not close the circuit and does not particularly increase the outflow resistance of the polymer solution 4, and therefore does not cause clogging. The chargeability of the polymer liquid 4 flowing out by extending the charge concentration portion in the opening 1c can be enhanced. In the case where the charging effect is enhanced by such a projecting piece 1d, it is easy to prevent a bias in charging by arranging the plurality of projecting pieces 1d evenly in the circumferential direction. The larger the number of projecting pieces 1d, the more the charging performance can be improved and the bias can be prevented. However, since the outflow resistance increases, the condition may be selected as necessary. In particular, in this example, since the protruding piece 1d is provided under the condition that the length L1 of the small hole 5 is zero, the outflow resistance of the polymer solution 4 can be kept low even if the protruding piece 1d is extended as shown in the figure. It becomes easy to provide a plurality of protruding pieces 1d.

  Here, the correlation between the applied charge concentration distance L and the number of polymer fibers to be generated, which the inventor has found in experiments, will be described as shown in FIG. The number of polymer fibers produced from 1 mm to 3 mm was obtained by using the nozzle 1 in which the applied voltage concentration distance L was increased to about 1 mm to 5 mm in increments of 1 mm, and polymer fibers were produced under the same conditions. Increases substantially proportionally, and when it exceeds 3 mm, the number of polymer fibers produced shows a slight increase but becomes almost flat. The increase in charging efficiency with respect to the outflowing polymer liquid 4 due to the charge concentration accompanying the increase in the applied voltage concentration distance L from 1 mm to 3 mm increases the number of polymer fibers produced, and the polymer exceeds 3 mm. The tendency for the number of fibers to be leveled off is considered to be the effect of suppressing the outflow of the polymer solution 4 as the nozzle 1 becomes longer regardless of the increase in charging efficiency.

  In FIG. 5, the measurement of the number of fibers is an experiment conducted with the weight of fibers generated within a predetermined time.

  Therefore, the applied power concentration distance L of the nozzle 1 may be 3 mm or more, but is preferably 10 mm or less from the viewpoint of increasing the outflow resistance and preventing clogging. In particular, the short nozzle 1 whose applied power concentration distance L has a lower limit of 3 mm satisfies the charge concentration in the opening 1c, and the polymer solution 4 can be stably discharged so as not to clog with less resistance. Thereby, it becomes advantageous also for cost reduction and weight reduction when many nozzles 1 are used.

  The supply of the polymer solution 4 is pumped into the container 2 through the polymer solution supply pipe 22 by the pump 11 as shown in FIG. 1A, and the polymer solution 4 is pressurized and sprayed from the small holes 5. Accordingly, it is suitable for further refinement of polymer fiber generation and increase in the generation amount that the polymer solution 4 is also pressurized and flowed out more quickly and in a large amount from the small holes 5. In this case, the diameter forming the opening area A1 of the small hole 5 is preferably set in a range of about 0.1 mm to 0.9 mm in order to produce a nano-unit polymer fiber, and the area A3 of the opening 1c is set to be small. The diameter formed is naturally larger than the diameter forming the opening area A1 of the small hole 5, but it is preferable to make it as small as possible in order to increase the charging efficiency with respect to the polymer liquid 4 flowing out. Moreover, although the diameter which makes passage cross-sectional area A3 of the polymer solution supply path 6 is made larger than the diameter which makes opening area A1, it is easier to clean when making it large at a rear end. However, in consideration of the influence on the outer diameter of the rear end in terms of reducing the arrangement pitch of the nozzles 1, it is preferable that the maximum is about 10 mm, and the area A4 shown in FIG. The diameter is preferably about 12 mm.

  As a polymer fiber production apparatus 10 using the nozzle 1 as described above, as shown in FIG. 1A, the polymer liquid 4 is charged with the high voltage V1 from the high voltage generator 3 and the container 2 is small. In a polymer fiber generating device that flows out of the hole 5 and generates a polymer fiber accompanied by at least stretching by electrostatic explosion, a plurality of nozzles 1 for polymer fiber generation as described above are provided in a plurality of containers 2, respectively. It is preferable that the small holes 5 are formed. Thus, by providing a plurality of nozzles 1 for polymer fiber generation in the container 2, polymer fibers can be simultaneously generated from a plurality of locations while taking advantage of the above characteristics according to the type of each nozzle 1. Accordingly, the amount of polymer fiber produced per unit time can be further increased. For this purpose, it is preferable to provide more nozzles 1 in the container 2 as in the example shown in FIG. 6, the example shown in FIG. 7, and the example shown in FIG.

  In particular, it is provided on the outer periphery of the container 2 that is rotationally driven as in the example shown in FIG. 7 and the example shown in FIG. The polymer fiber 4 is generated by the outflow of the polymer liquid 4 due to the centrifugal force from the small hole 5 of the nozzle 1 provided on the outer periphery of the container 2 and the centrifugal force of the outflowed polymer liquid 4 and stretching due to electrostatic explosion. As a result, the amount of polymer fiber generated is increased by the amount of centrifugal force acting on the outflow of the polymer solution from the nozzle, and the outflow amount and stretchability are increased. With this, the amount of polymer fiber produced can be further increased. In both the example shown in FIG. 7 and the example shown in FIG. 8, the reflecting member charged to the same polarity as the charged polarity of the polymer fiber formed by the polymer solution 4 flowing out to one end side in the axial direction of the container 2 is used. By arranging, the continuously generated polymer fiber is caused to fly toward the other end side of the container 2 in the axial direction, and is collected in a collector or the like that is charged with a reverse polarity (not shown) or connected to the ground. Although the collection efficiency can be increased, in the case of the container 2 installed in the horizontal direction in the example shown in FIG. 7, the collection at the other end in the axial direction needs to overcome gravity, but the vertical direction in the example shown in FIG. 8. In this example, there is an advantage that the gravitational action can be effectively used to increase the collection efficiency by flying the generated polymer fiber downward by the reflecting member. In the example of FIG. 7, the example of FIG. 8, and the example of FIG. 9, the power supply path 17 is provided so as to cover the entire surface of the container 2, and the power supply path 17 is connected to the entire circumference of the high voltage application unit 1 b of the nozzle 1. Therefore, the voltage application efficiency is improved. For this purpose, it is not necessary to cover the entire surface of the container 2, and it may be branched from the connection position with the high voltage generator 3, which is an external power supply, so as to be provided only in the region where the nozzles 1 are arranged. However, depending on the case, it can also form in the shape of a line which connects part of the circumferential direction of the high voltage application part 1b of the nozzle 1 mutually.

  As a polymer fiber production apparatus 10 provided with the container 2 that is rotationally driven as described above, as representatively shown in the example of FIG. 7, the drive means 13 that rotationally drives the container 2 with a motor 12 or the like, and the height of the nozzle 1 A high voltage applying means 14 for applying a high voltage from the high voltage generating section 3 to the voltage applying section 1b, and a polymer solution 4 is supplied to the container 2 by a pump 11 or the like, and at least the container 2 is rotationally driven from the small hole 5 of the container 2. The polymer liquid supply means 15 that flows out by the centrifugal force of the above, the drive means 13, the high voltage application means 14, and the control means 16 that controls the polymer liquid supply means 15 according to the setting may be used. The means 16 controls the drive means 13, the high voltage application means 14, and the polymer solution supply means 15 of the container 2 according to the initial setting based on the control program and the stored data, or the settings input by the operator from the operation panel 18. It can automatically generate a polymer fiber configuration as stably set as Te. In addition, when there is a control target for providing the collecting means to form the polymer web manufacturing apparatus, the control target may be controlled by the control means 16.

  Finally, in each of the examples shown in FIGS. 1 to 4 and FIGS. 6 to 8, the high voltage applying means 14 is connected to the power supply path 17 on the container 2 as representatively shown in FIG. The high voltage generating unit 3 that is one external power supply and the high voltage applying unit 1b of the nozzle 1 are connected to each other. As a result, the plurality of nozzles 1 protrude from the high voltage application unit 1 b to the opening 1 c at the tip on the outer surface of the container 2, and each high voltage application unit 1 b has one power supply path 17 provided on the container 2. All are connected to the high voltage generator 3 as an external power supply and can receive a high voltage all at once. In particular, as shown in FIG. 1A, the nozzle 1 has a state in which the base 1a side is embedded up to the high voltage application unit 1b, and the high voltage application unit 1b is connected to a power supply path 17 formed in a layer on the outer surface of the container 2. It is supposed to be. As a result, the nozzle 1 is simply embedded and held on the outer surface of the container 2 so that the high voltage application section 1b protrudes from the opening 1c at the tip, and the high voltage application section is provided in the power supply path 17 provided on the container 2. 1b is connected to a high voltage generator 3 which is an external power supply and can receive a high voltage.

  Further, as shown in FIG. 1A, the nozzle 1 is embedded in the container 2 up to the high voltage applying part 1b on the base 1a side, and the high voltage applying part 1b is connected to the power supply path 17 formed in a layer on the outer surface of the container 2. I try to be in the state. As a result, the nozzle 1 is simply embedded and held on the outer surface of the container 2 so that the high voltage application section 1b protrudes from the opening 1c at the tip, and the high voltage application section is provided in the power supply path 17 provided on the container 2. There is an advantage that 1b is connected to the high voltage generator 3 which is an external power supply and can receive a high voltage. Further, when the nozzle 1 is mounted on the wall of the container 2 so as to be detachable, maintenance such as removal and cleaning can be performed. All of the cleaning etc. can be removed and replaced, and can be cleaned at a different location. As shown in FIG. 1A, the nozzle 1 can be attached to the removable container 2 by press-fitting from the inner surface side of the container 2 to prevent leakage of the polymer liquid 4 without any special sealing structure. If a flange 1e is provided at the base end of the base 1a of the nozzle 1 so that it does not escape to the outside due to pressure or centrifugal force, inadvertent removal can be prevented. Further, it can be mounted by screw fitting at a fine pitch instead of press-fitting.

  In the case of the container 2 that is rotationally driven in the examples shown in FIGS. 7 and 8, the polymer liquid supply means 15 is not vertically passed through the rotation shaft 21 of the container 2 as representatively shown in the example of FIG. 7. The rotating polymer liquid supply pipe 22 supplies the liquid into the container 2, but the rotating shaft 21 is supported by a bearing (not shown) as an insulator such as resin together with the container 2, and once a high voltage is generated on the fixed ring of the bearing. Connecting the nozzle 3 and the high voltage generator 3 that is an external power supply without connecting the part 3 and connecting the inner ring to the power feeding path 17 on the surface of the container 2 without the influence of the container 2 rotating. Can do.

  The present invention is practical for producing polymer fibers by electrospinning and is suitable for producing a large amount of polymer fibers.

BRIEF DESCRIPTION OF THE DRAWINGS It is the front view which shows the nozzle for polymer fiber production | generation of embodiment which concerns on this invention, a perspective view, the schematic diagram which shows the polymer fiber production | generation apparatus and polymer web manufacturing apparatus using this nozzle. It is sectional drawing, the front view, and perspective view which show the nozzle of another example for the polymer fiber production | generation of embodiment which concerns on this invention. It is sectional drawing, the front view, and perspective view which show the nozzle of the other example for the polymer fiber production | generation of embodiment which concerns on this invention. It is sectional drawing, a front view, a side view, and a perspective view which shows the nozzle of this example for the polymer fiber production | generation of embodiment which concerns on this invention. It is a graph which shows the correlation with the applied voltage concentration distance in the opening part of a small hole from the high voltage application part of a nozzle, and the production | generation number of a polymer fiber. It is a perspective view which shows typically the polymer fiber production | generation apparatus with which the nozzle of the example shown in FIGS. 1-4 is applied. It is a perspective view which shows typically the polymer fiber production | generation apparatus made into the rotation type horizontal type to which the nozzle of the example shown in FIGS. 1-4 is applied. It is a perspective view which shows typically the polymer fiber production | generation apparatus made into the rotary vertical type to which the nozzle of the example shown in FIGS. 1-4 is applied.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Nozzle 1a Base 1b High voltage application part 1c Opening part 1d Projection piece 2 Container 3 High voltage generation part 4 Polymer liquid 5 Small hole 10 Polymer fiber production | generation apparatus 11 Pump 12 Motor 13 Driving means 14 High voltage application means 15 Polymer Liquid supply means 16 Control means 17 Power supply path 22 Polymer liquid supply pipe

Claims (1)

In a nozzle for generating a polymer fiber that causes a polymer liquid to flow out of a small hole with charging by a high voltage and generate a polymer fiber at least with stretching due to electrostatic explosion,
At least the outer surface layer from the high voltage application part on the base side to the small hole opening part has a conductive part that charges the polymer liquid flowing out from the small hole to a high voltage, and the outer surface formed by the conductive part has a high voltage The applied portion is narrowed toward the small hole opening satisfying a predetermined applied voltage concentration distance, and the small hole opening is defined as a charge concentration portion. The charge concentration portion is high from at least one circumferential direction around the small hole opening. A nozzle for producing a polymer fiber, characterized in that it has a projecting piece extending in the outflow direction of the molecular liquid .

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