TW201831743A - Nanofiber manufacturing method and device - Google Patents

Abstract

Provided are a nanofiber manufacturing method and device for manufacturing nanofibers with a good yield ratio and good efficiency. A method for manufacturing nanofibers in which: an electrically charged solution in which a nanofiber material is dissolved in a solvent is discharged from the tip of a nozzle provided at such an orientation that the tip is faced upward; and nanofibers are manufactured, wherein the method has a fluid discharge step and a collection step. In the fluid discharge step, the solution is taken from the nozzle, the tip of which is placed in an atmosphere including the solvent of the nanofiber material. In the collection step, the solution taken from the nozzle is drawn into a collector that is electrically charged with the reverse polarity of the solution, whereby the nanofibers are collected.

Description

Nano fiber manufacturing method and device

The invention relates to a method and a device for manufacturing nanofibers.

As a method for producing a so-called nanofiber having a nanometer diameter of several nm or more and less than 1000 nm, for example, an electric field spinning method is known. The electric field spinning method is also called an electrospinning method, and is performed using an electric field spinning device (also called an electrostatic spinning device) having a nozzle, a collector, and a power source. In the electric field spinning device, a voltage is applied between the nozzle and the collector by a power source, for example, the nozzle is charged negatively, and the collector is charged positively. When a solution in which a raw material of nanofibers (hereinafter referred to as a nanofiber material) is dissolved in a solvent is sprayed from a tip of a nozzle under a voltage applied state, the solution is moved to a collector electrode by Coulomb force, and Collected on the collector as nanofibers.

The electric field spinning device includes a nozzle disposed above a collector. In this type of electric field spinning device, the solution may sometimes agglomerate at the tip of the nozzle. This block contains a solvent, and sometimes falls on the collecting surface of the nanofibers accumulated on the collector. In this case, it is necessary to remove the part of the accumulated nanofibers to which the above-mentioned pieces are attached, so the yield is impaired. Therefore, there is a method described in Japanese Patent Application Laid-Open No. 2012-167409 and International Publication No. 2014/057927, that is, a solution sprayed from a nozzle set with the front end facing upward is induced to a position above the nozzle The collector is thereby captured as a nanofiber.

In addition, there is a method described in Japanese Patent Application Laid-Open No. 2009-074224, that is, the solution is ejected from the nozzle while the nozzle and the collector are immersed in a bath in which the nanofiber material is not dissolved.

However, in the methods described in Japanese Patent Application Laid-Open No. 2012-167409 and International Publication No. 2014/057927, although the output of nanofiber is good, the tip of the nozzle is blocked by a block. When the tip of the nozzle is clogged, in order to remove the block from the tip of the nozzle, manufacturing is stopped and manufacturing efficiency is poor. In the method described in Japanese Patent Application Laid-Open No. 2009-074224, the nozzle is immersed in a bath in which the nanofiber material is insoluble, so it is the same as the method of Japanese Patent Laid-Open No. 2012-167409 and International Publication No. 2014/057927 The tip of the nozzle is clogged.

An object of the present invention is to provide a nanofiber manufacturing method and apparatus for manufacturing nanofibers with good yield and good efficiency.

In the nanofiber manufacturing method of the present invention, a nanofiber is produced by spraying a solution in which a nanofiber material is dissolved in a solvent and charged, from the tip of a nozzle provided with the front end facing upward. The nanofiber manufacturing method has Discharge step and capture step. In the liquid discharge step, the solution is ejected from a nozzle disposed at the front end in an environment containing a solvent containing nanofiber material. In the capturing step, the solution ejected from the nozzle is induced to a collector electrode having a polarity opposite to that of the solution, thereby collecting nanofibers.

The nozzle is arranged in a container containing a liquid solvent in a state protruding from the liquid level in the container to the front end, and the solvent gas formed by vaporizing the solvent in the container is preferably placed under the environment.

The distance between the tip and the liquid surface is preferably within a range of 2 mm to 15 mm.

The temperature of the solvent in the container is preferably at least 5 ° C lower than the boiling point of the solvent.

The angle of the nozzle with respect to the liquid surface is preferably within a range of 45 ° to 90 °.

The solvent can be supplied to the front end by spraying.

In the liquid discharge step, it is preferable to eject the solution from a plurality of nozzles spaced apart from each other in a range of 1 mm to 20 mm.

It is preferable that the tips of the plurality of nozzles are in the same direction.

Either the nanofiber material is a cellulose polymer or an elastomer. When the nanofiber material is a cellulose polymer, cellulose triacetate is more preferable. When the nanofiber material is an elastomer, an acrylic elastomer is preferred.

The solvent is preferably dichloromethane.

The nanofiber manufacturing apparatus of the present invention includes a nozzle, a container, a collector, and a voltage application unit. The nozzle ejects a solution in which the nanofiber material is dissolved in a solvent from the front end. The container holds the solvent of the nanofiber material. The collector induces the solution ejected from the nozzle to be captured as nanofibers. The voltage applying section applies a voltage to the solution and the collector ejected from the front end, so that the solution and the collector are charged with opposite polarities. The nozzle is provided in the container in a state where the front end faces upward and extends from the liquid level of the solvent to the front end. [Inventive effect]

According to the present invention, nanofibers can be manufactured with good yield and good efficiency.

FIG. 1 is a schematic view of a nonwoven fabric manufacturing facility 20 to which the present invention is implemented. The non-woven fabric manufacturing equipment 20 is used for manufacturing nano fiber 11 and non-woven fabric 10. The non-woven fabric 10 can be used, for example, as a dust-free cloth, a filter cloth, a medical non-woven cloth (referred to as a drape), etc. that comes into contact with a wound or the like.

The nonwoven fabric 10 is composed of nanofibers 11. The nanofiber 11 is produced by an electric field spinning method as a method for producing a nanofiber. The diameter of the nanofibers 11 is in a range of 50 nm to 2000 nm, and in this embodiment, it is approximately 400 nm.

The nonwoven fabric manufacturing facility 20 includes a solution preparation unit 21, a nanofiber manufacturing apparatus 22, and a pipe 33 connecting these.

The solution preparation unit 21 prepares a solution 25 for forming the nanofibers 11. The solution preparation unit 21 prepares (prepares) a solution 25 by dissolving the nanofiber material 15 in a solvent 31 of the nanofiber material. The solution 25 prepared by the solution preparation unit 21 is guided to the nanofiber manufacturing apparatus 22 through a pipe 33.

The nanofiber manufacturing apparatus 22 performs an electric field spinning method. In this example, the nanofiber manufacturing apparatus 22 has a plurality of nozzles 36a to 36c arranged in a state of being separated from each other. In the following description, when the nozzle 36a, the nozzle 36b, and the nozzle 36c are not distinguished, the nozzle 36 will be described. One end of the nozzle 36 is connected to the solution preparation unit 21 via a pipe 33. Thereby, the solution 25 guided by the solution preparation unit 21 is ejected from the other end of the nozzle 36. One end of the nozzle 36 that is connected to the solution preparation portion 21 is referred to as a "base end", and the other end of the nozzle 36 that ejects the solution 25 is referred to as a "front end". The solution 25 sprayed from the front end of the nozzle 36 forms the nanofibers 11.

In this example, a long support body 37 is used for the accumulation of the nanofibers 11 and the support of the nonwoven fabric, and the support body 37 is moved in the longitudinal direction. The details of the support body 37 will be described later with reference to other drawings. The widthwise direction of the support body 37 in FIG. 1 and the depth direction of the paper surface in FIG. 1 indicate the moving direction of the support body 37. The nozzles 36 a to 36 c are arranged in a state of being aligned in the width direction of the support body 37. Although three nozzles 36 are used in this example, the number of nozzles 36 is not limited to this. In addition, each pipe 33 is provided with a pump 38 that sends a solution 25 to the nozzle 36. By changing the rotation speed of the pump 38, the flow rate of the solution 25 ejected from the nozzle 36 is adjusted.

The nanofiber manufacturing apparatus 22 will be described with reference to FIG. 2. FIG. 2 illustrates the case viewed from the nozzle 36 a side of FIG. 1. To avoid complication of the drawing, only the nozzle 36 a is illustrated for the nozzle 36, and the illustration of the nozzles 36 b and 36 c is omitted. The nanofiber manufacturing apparatus 22 includes a spinning chamber 45, the aforementioned nozzle 36, a container 46, an accumulation section 47, a conducting member 48, a power source 49, and the like.

The spinning chamber 45 contains, for example, the nozzle 36, the container 46, a part of the accumulation portion 47, and the like. In the spinning chamber 45, a nozzle 36 and a container 46 are arranged at a lower portion, and an accumulation portion 47 is arranged at an upper portion. The spinning chamber 45 is configured to be hermetically sealed to prevent leakage of the solvent gas and the like to the outside. The solvent 31 of the solvent gas system solution 25 is vaporized.

The nozzle 36 is provided in the container 46 with the front end facing upward. That is, the nozzle 36 is in a state where the front end of the ejection solution 25 faces the collector electrode 58 disposed above the nozzle 36. The solution 25 sprayed from the nozzle 36 moves toward the collector electrode 58 through the opening provided in the container 46. When the solution 25 is ejected from an opening (hereinafter, referred to as a tip opening) formed at the tip of the nozzle 36, the tip 25 is opened at the tip, and a substantially conical Taylor cone 53 is formed by the solution 25.

The container 46 contains a solvent 50 of the nanofiber material 15. The solvent 50 is a liquid. When the solvent 50 is vaporized, the tip of the nozzle 36 is disposed in an environment containing the solvent 50 in a gaseous state. Hereinafter, the solvent in this gas state is referred to as a solvent gas 80. In this example, the nozzle 36 is attached to the bottom of the container 46, but the method of attaching the nozzle 36 to the container 46 is not limited to this. For example, the base end of the nozzle 36 may be connected to the hose through the bottom of the container 46, and the nozzle 36 may be attached to the container 46 through the hose. It should be noted that the solvent 50 is only required if the nanofiber material 15 is soluble. Examples of the solvent 50 include the same as the solvent 31.

The container 46 is connected to a pipe 33 for guiding the solvent 50 sent from the pump 38. The container 46 is provided with a liquid level sensor 54 that detects the level of the liquid level 52 of the solvent 50. Based on the detection signal of the liquid level sensor 54, the injection amount of the solvent 50 into the container 46 is controlled, and the pressure in the container 46 is adjusted. The height of the liquid surface 52. The height of the liquid surface 52 in the container 46 is lower than the height of the tip of the nozzle 36 provided in the container 46. That is, the nozzle 36 is provided in the container 46 in a state where the tip extends from the liquid surface 52 of the solvent 50.

The container 46 is provided with a temperature sensor 56 that detects the temperature of the solvent 50, and the temperature of the solvent 50 in the container 46 is adjusted by a temperature adjustment unit (not shown) based on a detection signal of the temperature sensor 56. In the present embodiment, the temperature of the solvent 50 in the container 46 is set to be lower than the boiling point of the solvent 50 by, for example, 5 ° C.

The accumulation portion 47 includes a collector 58, a collector rotation portion 59, a support supply portion 60, and a support winding portion 61. The collector electrode 58 is used to induce the solution 25 ejected from the nozzle 36 to be captured by the nanofiber 11. In the present embodiment, the collector electrode 58 is captured on a support 37 described later. The collector electrode 58 is composed of an endless belt formed of a metal belt. The collector electrode 58 may be formed of a material that is charged by applying a voltage to the power source 49, and is made of, for example, stainless steel. The collector rotating portion 59 is composed of a pair of rollers 62, rollers 63, a motor 64, and the like. The collector electrode 58 is horizontally wound around a pair of rollers 62 and 63. A motor 64 disposed outside the spinning chamber 45 is connected to the shaft of one roller 62 to rotate the roller 62 at a predetermined speed. By this rotation, the collector electrode 58 moves so as to circulate between the roller 62 and the roller 63. In this embodiment, the moving speed of the collector 58 is set to 10 cm / hour, but it is not limited to this.

A support 37 made of a strip-shaped aluminum sheet is supplied to the collector electrode 58 via a support supply unit 60. The support 37 is used for accumulating the nanofibers 11 and obtained as the nonwoven fabric 10. The support body supply unit 60 includes a sending-out shaft 60a. A support roller 65 is attached to the delivery shaft 60a. The support body roller 65 is configured by winding the support body 37 around the winding core 66. The support body winding section 61 includes a winding shaft 67. The take-up shaft 67 is rotated by a motor (not shown), and the support body 37 on which the nonwoven fabric 10 is formed is taken up by the attached roll core 68. In this way, the nanofiber manufacturing apparatus 22 has a function of manufacturing nanofibers 11 and a function of manufacturing nonwoven fabrics 10, and performs the production of nanofibers and nonwoven fabrics based on the electric field spinning method. In addition, the support body 37 may be placed on the collector electrode 58 and moved by the movement of the collector electrode 58.

In addition, the accumulation of the nanofibers 11 and the formation of the non-woven fabric 10 can also be performed directly on the collector 58. However, depending on the raw materials forming the collector 58 or the surface state of the collector 58, the nanofibers 11 and the non-woven 10 are attached. , Sometimes difficult to peel. Therefore, as in this embodiment, it is preferable to guide the support body 37 to which the nanofibers 11 and the nonwoven fabric 10 are not easily attached, and to accumulate the nanofibers 11 on the support 37.

The conducting member 48 is disposed below the container 46. The conducting member 48 is electrically connected to the base end of the nozzle 36 protruding from below the container 46.

The power source 49 is a voltage application unit that applies a voltage to the nozzle 36 and the collector 58 to charge the nozzle 36 to a first polarity and to charge the collector 58 to a second polarity opposite to the first polarity. By passing through the charged nozzle 36, the solution 25 is charged and ejected from the nozzle 36 in a charged state. The power source 49 is connected to the conduction member 48 and applies a voltage to the nozzle 36 via the conduction member 48. The method of applying a voltage to the nozzle 36 is not limited to this. For example, a voltage may be applied to the nozzle 36 by connecting the power source 49 to the nozzle 36. In this embodiment, the nozzle 36 is positively charged (+) and the collector 58 is negatively charged (-), but the polarity of the nozzle 36 and the collector 58 may be reversed. The potential of the collector 58 can be set to ground by grounding it. In this embodiment, the voltage applied to the nozzle 36 and the collector 58 is set to 30 kV. By this charging, the solution 25 is ejected from the Taylor cone 53 and the solution 25 as a spinning jet 69 to the collector 58. In this example, the solution 25 is charged by applying a voltage to the nozzle 36, but the solution 25 may be charged in the pipe 33 and the charged solution 25 may be guided to the nozzle 36.

The distance L1 between the nozzle 36 and the collector 58 depends on the type of the nanofiber material 15 and the solvent 31, the mass ratio of the solvent 31 in the solution 25, and the like. The appropriate value is different, but it is more within a range of 30 mm to 300 mm. Preferably, it is 180 mm in this embodiment.

The voltage applied to the nozzle 36 and the collector 58 is preferably 2 kV or more and 40 kV or less. From the viewpoint of forming the nanofiber 11 finely, it is preferable that the voltage be as high as possible within this range.

Hereinafter, a method for producing a nanofiber will be described. From the front end of the nozzle 36 provided with the front end facing upward, a solution 25 in a state where the nanofiber material 15 is dissolved in the solvent 31 and charged is sprayed, thereby producing a nanofiber in the nanofiber 11. Steps of ejecting the solution 25 from the nozzle 36 disposed at the front end under the environment containing the solvent 50 of the nanofiber material 15; and a trapping step of inducing the solution 25 ejected from the nozzle 36 to the collector electrode 58 charged with the opposite polarity of the solution 25 Thus, the nanofibers 11 are captured. With the tip of the nozzle 36 facing upward as described above, even when the solution 25 forms a block at the tip of the nozzle 36, the block does not fall on the nanofibers 11 accumulated on the collector 58. Furthermore, by disposing the tip of the nozzle 36 in an environment containing the solvent 50, the block is prevented from adhering to the tip of the nozzle 36, and clogging of the tip of the nozzle 36 is prevented. As a result, the nanofibers 11 are produced with good yield and good efficiency.

The nozzle 36 is disposed in a container 46 containing the liquid solvent 50 in a state where the tip extends from the liquid surface 52 in the container 46. Thereby, the front end of the nozzle 36 is placed in an environment containing the solvent 50 by the solvent gas 80. Therefore, clogging of the tip of the nozzle 36 is more reliably prevented.

The solvent 50 may be supplied to the tip of the nozzle 36 by spraying. When spraying the solvent 50, for example, the amount of the sprayed solvent 50 is adjusted by a solvent spraying device (not shown), and it is preferable that the shape and the like of the Taylor cone 53 are not changed. Thereby, the block of the solution 25 is more suppressed from adhering to the front end of the nozzle 36, and the front end of the nozzle 36 is more reliably prevented from being clogged. As a result, the production efficiency of the nanofibers 11 is further improved. Further, instead of spraying the solvent 50 or replacing the spray of the solvent 50, the solvent 50 may be supplied to the tip of the nozzle 36 in a gas state. In addition, as a method for disposing the tip of the nozzle 36 in an environment containing the solvent 50, either the case of the container 46 containing the liquid solvent 50 or the case of spraying the solvent 50 can be appropriately selected, and among these, the container The container 46 having the liquid solvent 50 is more preferable because it does not change the shape of the Taylor cone 53.

The distance L2 between the tip of the nozzle 36 and the liquid surface 52 shown in FIG. 1 is preferably in a range of 2 mm or more and 15 mm or less. Since the distance L2 is 2 mm or more, the liquid solvent 50 is not higher than the front end of the nozzle 36 compared to when the distance is less than 2 mm, so the spinning is more stable. When the distance L2 is 15 mm or less, compared with when the distance is greater than 15 mm With a high concentration of solvent gas, spinning is more stable. The distance L2 is more preferably in a range of 2 mm to 10 mm, and more preferably in a range of 3 mm to 10 mm. In this embodiment, it is set to, for example, 5 mm.

The temperature of the solvent 50 in the container 46 is lower than the boiling point of the solvent 50 by 5 ° C or more, that is, it is preferably lower than the boiling point of the solvent 50 by at least 5 ° C. This is because the higher the temperature of the solvent 50 is, the more the gasification is promoted. Therefore, when the temperature of the solvent 50 in the container 46 is too close to the boiling point, the solvent 50 in the container 46 is dried up immediately. When the temperature of the solvent 50 is too close to the boiling point, the temperature of the solution 25 increases through the nozzle 36, which promotes the vaporization of the solvent 31, and the uniformity of the shape of the nanofibers 11 may be damaged. When the shape of the obtained nanofibers 11 is not uniform, depending on the application, portions different from the desired shape may be removed, and as a result, the yield may be impaired. Therefore, from the viewpoint of yield, it is preferable that the temperature of the solvent 50 is sufficiently lower than the boiling point. On the other hand, from the viewpoint of efficiency, it is preferable that the concentration of the solvent gas is high, and therefore, the temperature of the solvent 50 is preferably high. Thereby, from the viewpoint of more reliably improving the yield and efficiency, the temperature of the solvent 50 in the container 46 is preferably lower than the boiling point of the solvent 50 by at least 5 ° C and as high as possible.

The angle θ of the nozzle 36 with respect to the liquid surface 52 will be described. Here, θ is set to 0 ° when the longitudinal direction of the nozzle 36 is horizontal, and θ is set to 90 ° when vertically oriented. Since the nozzle 36 faces upward, it is 0 ° <θ <90 °. The closer this angle θ is to 90 °, the smaller the voltage required to move the solution 25 ejected from the nozzle 36 toward the collector 58 is. The smaller the voltage applied to the nozzle 36, the more the vaporization of the solvent 31 in the tip of the nozzle 36 is suppressed, and the clogging of the nozzle 36 is more suppressed. Therefore, the angle θ is preferably in a range of 45 ° or more and 90 ° or less, more preferably in a range of 75 ° or more and 90 ° or less, and 90 ° is most preferable. In this embodiment, the angle θ is set to, for example, 90 °.

In this example, the plurality of nozzles 36a to 36c are spaced apart from each other within a range of 1 mm to 20 mm. When the distance between the nozzles 36 shown in FIG. 1 is L3, since the distance L3 is 1 mm or more, the discharge between the nozzles 36 is suppressed compared to when the distance L3 is less than 1 mm, thereby stably spinning. Since the distance L3 is 20 mm or less, the device can be made more compact than when the distance is larger than 20 mm. The distance L3 is more preferably within a range of 3 mm to 10 mm. In this embodiment, the distance L3 is set to, for example, 5 mm.

It is preferable that the tip ends of the plurality of nozzles 36a to 36c are in the same direction. Regarding the direction of the nozzles, "same" is considered to be the same as long as the angle θ of each nozzle 36 is completely the same, as long as it is 0 ° or more and 45 ° or less. By having the front ends of the plurality of nozzles 36a to 36c in the same direction, it is possible to obtain a nonwoven fabric having a more uniform mass per unit fiber area, that is, a more uniform thickness. The fiber unit area mass is the mass per unit area of the nonwoven fabric. Depending on the application, non-woven fabrics with uneven thickness are sometimes partially removed, and non-woven fabrics with uniform thickness can be used in their entirety, so the yield is better.

The solution preparation unit 21 dissolves the nanofiber material 15 in the solvent 31 to prepare a solution 25.

The nanofiber material 15 is preferably a cellulose polymer or an elastomer.

Any one of the cellulose-based polymer cellulose compounds, the nitrocellulose, ethyl cellulose, and carboxymethyl ethyl cellulose as the nanofiber material 15 is preferable. As the cellulose halide, cellulose acetate, cellulose propionate, cellulose butyrate, and cellulose acetate propionate are more preferable. As cellulose acetate, cellulose triacetate and cellulose diacetate are more preferable. When a cellulose-based polymer is used as the nanofiber material 15, cellulose triacetate is particularly preferred.

In addition, as the elastomeric acrylic elastomer, styrene-based elastomer, olefin-based elastomer, vinyl chloride-based elastomer, urethane-based elastomer, and amidine-based elastomer as the nanofiber material 15, One is better. When an elastomer is used as the nanofiber material 15, an acrylic elastomer is particularly preferred.

Examples of the solvent 31 include methanol, ethanol, isopropanol, butanol, benzyl alcohol, acetone, methyl ethyl ketone, cyclohexanone, methyl acetate, ethyl acetate, propyl acetate, butyl acetate, and formic acid. Methyl ester, ethyl formate, hexane, cyclohexane, dichloromethane, chloroform, carbon tetrachloride, benzene, toluene, xylene, dimethylformamide, N-methylpyrrolidone, diethyl ether, Dioxane, tetrahydrofuran, 1-methoxy-2-propanol, and the like. These may be used alone or in combination depending on the type of the nanofiber material 15. Among these, dichloromethane (boiling point is 40 ° C.) is more preferable. In this embodiment, dichloromethane is used as the solvent 31.

A voltage is applied to the nozzle 36 and the collector 58 that is circulated by a power source 49. Thereby, the nozzle 36 is positively charged as the first polarity, and the collector 58 is negatively charged as the second polarity. The nozzle 36 is continuously supplied with the solution 25 from the solution preparation unit 21, and a support 37 is continuously supplied to the moving collector electrode 58. The solution 25 passes through the nozzle 36 and is charged to have a positive polarity as the first polarity, and is discharged from the front end of the nozzle 36 in a charged state.

The capture procedure will be described. The collector electrode 58 induces a solution 25 ejected from the front end opening in a state where the first polarity is charged. As a result, a Taylor cone 53 is formed at the front end opening, and a spinning jet 69 is ejected from the Taylor cone 53 toward the collector 58. The spinning jet 69 charged with the first polarity is split into narrow diameters due to its repulsion caused by its own charge while it faces the collector 58. As a result, the nanofibers 11 are manufactured and collected on the support 37.

The captured nanofibers 11 are sent to the support take-up section 61 together with the support 37 as the nonwoven fabric 10. The nonwoven fabric 10 is wound around the winding core 68 in a state overlapping with the support body 37. After the core 68 is detached from the take-up shaft 67, the nonwoven fabric 10 is separated from the support body 37. The nonwoven fabric 10 thus obtained is a long strip, but can be cut into a desired size afterwards, for example.

In this example, a cyclically moving belt is used as the collector 58, but the collector is not limited to the belt. For example, the collector may be a fixed flat plate or a cylindrical rotating body. In the case of a collector made of a flat plate or a cylindrical body, it is preferable to use the support 37 so that the nonwoven fabric can be easily separated from the collector. In addition, when a rotating body is used, a cylindrical nonwoven fabric made of nanofibers is formed on the peripheral surface of the rotating body. Therefore, after spinning, the cylindrical nonwoven fabric is drawn from the rotating body and cut into a desired size and shape. This can be used as a nonwoven product. [Example]

[Example 1] to [Example 20] In the nanofiber manufacturing apparatus 22, the types of the solvent 31, the type of the solvent 50, the number of the nozzles 36, and the like were changed, and the nanofibers 11 were continuously manufactured as Examples 1 to 20. The nanofiber material 15 used is described in the "nanofiber material" column in Table 1. As the nanofiber material 15, when cellulose acetate is used, it is described as "CA" in the "nano fiber material" column of Table 1, and when an elastomer is used, it is described as "elasticity" in the "nano fiber material" column of Table 1. body". Among them, "CA" uses cellulose acetate having a degree of substitution of ethyl acetate of 2.87, and "elastomeric" uses CLARITY (registered trademark) manufactured by Kuraray Co., Ltd., which is an acrylic elastomer.

When dichloromethane is used as the solvent 31, it is described as "dichloromethane" in the "solvent" column of Table 1, and when n-methylpyrrolidone is used, it is described as "NMP" in the "solvent" column of Table 1.

The presence or absence of the container 46 is described in the "presence or absence of a container" column in Table 1. When there is a container 46, the type of the solvent 50 is described in the "type of solvent" column in Table 1. The temperature difference between the solvent 50 and the boiling point of the solvent 50 in the container 46 (the temperature of the solvent 50 in the container 46)- (The boiling point of the solvent 50) is described in the column of "the temperature of the solvent in the container with respect to the boiling point of the solvent" in Table 1. When dichloromethane is used as the solvent 50, it is described as "dichloromethane" in the "type of solvent" column of Table 1, and when n-methylpyrrolidone is used, it is described as "type of solvent" in Table 1. "NMP". The presence or absence of spraying of the solvent 50 is described in the "presence or absence of spraying of a solvent" column in Table 1. The angle θ of the nozzle 36 is described in the "angle of the nozzle" column in Table 1. The number of nozzles 36 is described in the "Number of nozzles" column in Table 1. When a plurality of nozzles 36 are provided, whether the direction of the tip of each nozzle 36 is the same or different is described in the "Differences and differences of the directions of the nozzles" column in Table 1, and the distance between each nozzle 36 is described in "The Distance "column. In addition, in the "Differences in the directions of the nozzles" column in Table 1, when a plurality of nozzles 36 are set in the same direction, they are described as "same", and when at least one of the plurality of nozzles 36 is set in a different direction, they are described as "different." ". The distance between the tip of the nozzle 36 and the liquid surface in the container 46 is described in the "Distance between the tip of the nozzle and the liquid surface" in Table 1. In addition, when the number of nozzles 36 is set to one to manufacture the nanofibers 11, the "different directions of the nozzles" column and the "distance between the nozzles" column of Table 1 are described as "-".

The yield and efficiency were evaluated based on the following evaluation methods and benchmarks.

(1) Yield In the non-woven fabric 10 composed of the obtained nanofibers 11, the uniformity of the thickness of the non-woven fabric 10 and the uniformity of the shape of the nanofibers 11 were evaluated, and the yield was evaluated based on the following criteria based on each evaluation. Regarding the uniformity of the thickness of the non-woven fabric 10, a square sample with a length of 100 mm was cut out from the non-woven fabric 10 accumulated on the support 37, and the thickness of 10 samples was measured in the width direction with a contact film thickness measuring instrument. The maximum value of these measured values was subtracted from the average value, and the value was evaluated by dividing the value by the average value as a percentage. Regarding the uniformity of the shape of the nanofibers 11, a square sample with a length of 10 mm was cut out from the non-woven fabric 10 accumulated on the support 37, and the sample was SEM (Scanning Electron Microscope). The images were evaluated. Regarding the shape of the nanofibers 11 described below, "uniform" means that the thickness of the nanofibers 11 in the SEM image is approximately constant in the longitudinal direction, and "uneven" means that the nanofibers in the SEM image The thickness of 11 changes in the longitudinal direction. The non-uniformly shaped nanofibers 11 are, for example, in the middle of the nanofibers 11, and the shape of the droplets is round or spherical. A, B, and C are qualified, and D is unqualified. The results are shown in the "yield" column in Table 1. A: The uniformity of the thickness of the nonwoven fabric is within ± 10%, and the shape of the nanofibers is uniform. B: The uniformity of the thickness of the non-woven fabric exceeds ± 10%, but the shape of the nanofibers is uniform, which is a level without problems in practical use. C: The shape of the nanofiber is not uniform, but the uniformity of the thickness of the non-woven fabric is within ± 10%, which is a level without problems in practical use. D: The uniformity of the thickness of the nonwoven fabric exceeds ± 10%, and the shape of the nanofibers is uneven.

(2) Efficiency After continuous spinning for 20 minutes, the presence or absence of a block of the solution 25 at the tip of the nozzle 36 and the ejection method of the solution 25 from the nozzle 36 were visually confirmed, and evaluated based on the following criteria. A and B are qualified and C is unqualified. The results are shown in the "Efficiency" column in Table 1. A: No block of the solution adhered to the tip of the nozzle, and no clogging of the nozzle occurred. B: A very small amount of a block of the solution adhered to the tip of the nozzle, but no clogging of the nozzle occurred. C: No solution was ejected from the nozzle.

[Table 1]

[Comparative Example 1] As an example in which the nozzle 36 was not in an environment containing a solvent 50, a container 46 was not used to produce nanofibers, and this was taken as Comparative Example 1. The nanofiber materials and solvents used are shown in Table 1. The other conditions are the same as in the examples.

The yield and efficiency were evaluated according to the same methods and benchmarks as in the examples. The evaluation results are shown in Table 1.

10‧‧‧ Non-woven

11‧‧‧ Nanofiber

15‧‧‧Nano fiber material

20‧‧‧Non-woven manufacturing equipment

21‧‧‧Solution Preparation Department

22‧‧‧Nano fiber manufacturing equipment

25‧‧‧ solution

31‧‧‧Solvent

33‧‧‧Piping

36‧‧‧ Nozzle

36a ～ 36c‧‧‧‧Nozzle

37‧‧‧ support

38‧‧‧Pump

45‧‧‧spinning room

46‧‧‧container

47‧‧‧Accumulation Department

48‧‧‧Conducting member

49‧‧‧ Power

50‧‧‧ Solvent

52‧‧‧Liquid level

53‧‧‧Taylor cone

54‧‧‧Liquid level sensor

56‧‧‧Temperature sensor

58‧‧‧collector

59‧‧‧collector rotating part

60‧‧‧Support body supply department

60a‧‧‧ send out shaft

61‧‧‧Support body winding section

62‧‧‧roller

63‧‧‧roller

64‧‧‧ Motor

65‧‧‧ support roller

66‧‧‧ core

67‧‧‧ Reel

68‧‧‧ core

69‧‧‧ spinning jet

80‧‧‧ solvent gas

L1‧‧‧Distance between nozzle and collector

L2‧‧‧The distance between the front end of the nozzle and the liquid surface

L3‧‧‧Distance between nozzles

θ‧‧‧ Nozzle angle

Fig. 1 is a schematic view of a nonwoven fabric manufacturing facility. Fig. 2 is a schematic view of a nanofiber manufacturing apparatus.

Claims (13)

A method for manufacturing nanofibers, which sprays a solution in which a nanofiber material is dissolved in a solvent and is charged from the front end of a nozzle provided with the front end facing upward, thereby manufacturing nanofibers. The method for manufacturing nanofibers has: Steps of ejecting the solution from the nozzle disposed at the front end under an environment containing a solvent of the nanofiber material; and a trapping step of inducing the ejected from the nozzle to a collector charged with an opposite polarity to the solution The solution, thereby trapping the nanofibers. The nanofiber manufacturing method according to item 1 of the scope of the patent application, wherein the nozzle is arranged in a container containing the solvent of the liquid in a state protruding from the liquid surface in the container to the front end, and by the The solvent gas formed by vaporizing the solvent in the container, and the front end is placed in the environment. The nanofiber manufacturing method according to item 2 of the scope of patent application, wherein the distance between the front end and the liquid surface is in a range of 2 mm or more and 15 mm or less. The method for producing nanofibers according to item 2 or item 3 of the scope of patent application, wherein the temperature of the solvent in the container is at least 5 ° C lower than the boiling point of the solvent. The nanofiber manufacturing method according to item 2 of the scope of patent application, wherein the angle of the nozzle with respect to the liquid surface is in a range of 45 ° or more and 90 ° or less. The method for producing nanofibers according to item 1 of the scope of patent application, wherein the solvent is supplied to the front end by spraying. The nanofiber manufacturing method according to item 1 of the scope of patent application, wherein in the liquid discharge step, the solution is ejected from a plurality of the nozzles spaced apart from each other within a range of 1 mm to 20 mm. The nanofiber manufacturing method according to item 7 of the scope of patent application, wherein the front ends of the plurality of nozzles are in the same direction. The nanofiber manufacturing method according to item 1 of the patent application scope, wherein the nanofiber material is a cellulose polymer or an elastomer. The method for producing nanofibers according to item 9 of the scope of patent application, wherein the cellulose polymer is cellulose triacetate. The method for producing a nanofiber according to item 9 of the scope of patent application, wherein the elastic system is an acrylic elastomer. The method for producing nanofibers according to item 1 of the scope of patent application, wherein the solvent is methylene chloride. A nanofiber manufacturing apparatus includes: a nozzle that sprays a solution in which a nanofiber material is dissolved in a solvent from a front end; a container that contains the solvent of the nanofiber material; a collector electrode that induces the solution sprayed from the nozzle Trapped as nano-fibers; and a voltage applying section that applies a voltage to the solution and the collector ejected from the front end so that the solution and the collector are charged with opposite polarity; and the nozzle is in the container, It is set with the front end facing upward and in a state where the front end is protruded from the liquid level of the solvent.