Melt spinning device and method for producing fiber using the same

Abstract

To provide a melt spinning device in which the generation of foreign matters caused by the carbonization of a resin is suppressed and capable of stable melt spinning.SOLUTION: A melt spinning device comprises: a nozzle 31 discharging a molten resin; a gas flow passage 40 arranged so as to surround the nozzle 31 along the circumferential direction thereof; and a gas jet part 40a connected to the gas flow passage 40 and feeding a heated gas flow A to the gas flow passage 40. The gas flow passage 40 is composed in such a manner that the heated gas flow A circulates along an extending direction of the nozzle 31 from a trailing end of the nozzle 31 toward a leading end. A heat insulation material 60 is provided along the circumferential direction of the nozzle 31 between the gas flow passage 40 and the nozzle 31 and at a position of the trailing end side in the extending direction of the nozzle 31.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a melt spinning apparatus and a method for producing fibers using the same.

Background Art

[0002] The electrospinning method has attracted attention as a technique capable of simply and highly productively producing a fiber sheet having fibers with a nanosize diameter by discharging a solution or melt of a raw material resin. Generally, in the electrospinning method, a high voltage is applied between a nozzle for discharging a raw material resin liquid and a collecting electrode installed opposite to a position at a predetermined distance from the nozzle, and the raw material resin liquid is discharged in that state. The raw material resin liquid discharged from the tip of the nozzle is cooled and solidified while being stretched by the Coulomb force, thereby forming finer-diameter fibers. The present applicant has proposed an apparatus for producing fibers using this technique and a method for producing the same (see Patent Document 1).

[0003] In the electrospinning method using a melt of a raw material resin, maintaining the molten state of the raw material resin and stretching it even after discharging the melt leads to a reduction in the diameter of the produced fibers and an improvement in production efficiency. In the electrospinning apparatus described in Patent Document 1, in order to maintain the heated state of the melt even after discharging, the discharged melt is conveyed to a heated gas stream. For this purpose, in the electrospinning apparatus described in the same document, heated gas is introduced into the apparatus.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, when heated gas is introduced into an electrospinning apparatus, the molten resin circulating within the apparatus is excessively heated by the gas, and if the electrospinning apparatus is operated for a long time, carbides may be generated in the molten resin. The generation of carbides hinders stable spinning.

[0006] Therefore, the object of the present invention is to provide a melt spinning apparatus that suppresses the generation of carbides and enables stable melt spinning. [Means for solving the problem]

[0007] The present invention relates to a nozzle for dispensing molten resin, A gas flow path is arranged to surround the nozzle along its circumferential direction, A gas injection unit connected to the aforementioned gas flow path and supplying a heated gas flow to the aforementioned gas flow path, A melt spinning apparatus equipped with, The gas flow path is configured such that the heated gas flow flows along the extending direction of the nozzle, from the rear end towards the tip of the nozzle. The present invention provides a melt spinning apparatus that includes a heat insulating material along the circumferential direction of the nozzle, located between the gas flow path and the nozzle, and at the rear end of the nozzle in the extending direction. [Effects of the Invention]

[0008] According to the melt spinning apparatus of the present invention, the generation of foreign matter caused by carbonization of the resin is suppressed, enabling stable melt spinning. [Brief explanation of the drawing]

[0009] [Figure 1] Figure 1 is a schematic cross-sectional view showing one embodiment of the melt spinning apparatus of the present invention. [Figure 2] Figure 2 is a graph showing the change in the temperature of the molten resin when melt spinning is performed according to the present invention and the prior art. [Figure 3] Figure 3 is a schematic cross-sectional view showing another embodiment of the melt spinning apparatus of the present invention. [Figure 4] Figure 4 is a schematic cross-sectional view showing yet another embodiment of the melt spinning apparatus of the present invention. [Figure 5] Figure 5 is a graph showing the simulation results of melt spinning performed according to the present invention. [Modes for carrying out the invention]

[0010] The present invention will be described below with reference to the drawings, based on preferred embodiments thereof. Figure 1 shows the structure of an electrospinning apparatus 10, which is one embodiment of the melt spinning apparatus of the present invention. As shown in the figure, the electrospinning apparatus 10 comprises a kneading device 20 and a spinning unit 30.

[0011] The electrospinning apparatus 10 is equipped with a kneading apparatus 20. The kneading apparatus 20 melts the resin that will be used as the raw material for the fibers and discharges it to the spinning unit 30, which will be described later. The kneading apparatus 20 has a cylinder equipped with a heater and a screw (not shown) inside, and is structured to melt and knead the raw material resin supplied into the kneading apparatus 20 and then extrude it to be supplied to the spinning unit 30.

[0012] The electrospinning apparatus 10 includes a spinning unit 30. The spinning unit 30 spins by discharging molten resin supplied from the kneading apparatus 20 to the outside. The spinning unit 30 includes a hollow nozzle 31 that communicates with the kneading apparatus 20. The nozzle 31 consists of a tip area 31a and a cylindrical resin supply passage 31b connected to the rear end of the tip area 31a. The nozzle 31 is configured to discharge molten resin supplied from the kneading apparatus 20 from the tip area 31a via the resin supply passage 31b. From the viewpoint of improving electrostatic properties, it is preferable that the tip area 31a of the nozzle 31 is made of a conductor such as metal. Furthermore, from the viewpoint of improving heat resistance, it is preferable that the resin supply passage 31b of the nozzle 31 is made of metal. In the following explanation, unless otherwise specified, the direction of extension of the nozzle 31 (left-right direction in Figure 1) toward the mixing device 20 (left side in Figure 1) will also be referred to as the "rear" or "rear end direction," and the direction opposite to this (right side in Figure 1) will also be referred to as the "front" or "tip direction."

[0013] As shown in Figure 1, the spinning unit 30 is equipped with an electrode 32 for charging the tip region 31a of the nozzle 31 and generating an electric field between the tip region 31a and the electrode. The electrode 32 is made of a conductive material. In the figure, the electrode 32 is cylindrical in shape and is positioned to surround the nozzle 31 along its circumferential direction. The surface of the electrode 32 facing the nozzle 31 is formed as a concave curved surface on the inner surface of the cylinder. For convenience of explanation, in the following description, the surface of the electrode 32 facing the nozzle 31 will also be referred to as the "concave curved surface 32a". The electrode 32 has an open end 32c on the tip side of the nozzle 31. The planar shape of the open end 32c is circular, such as a perfect circle or an ellipse. The open end 32c is located in front of the tip portion of the tip region 31a of the nozzle 31. The electrode 32 is connected to a high-voltage power supply (not shown), and a positive or negative voltage is applied by this device.

[0014] The spinning unit 30 shown in Figure 1 has a structure formed between the kneading device 20 and the tip area 31a of the nozzle 31, consisting of a cylindrical resin supply passage 31b which forms part of the nozzle 31, an inner cylinder 36 arranged to surround the resin supply passage 31b, and an outer cylinder 37 which covers the inner cylinder 36. The rear end of the resin supply passage 31b is in communication with the kneading device 20, allowing molten resin supplied from the kneading device 20 to flow toward the tip area 31a of the nozzle 31. The cylindrical space formed between the resin supply passage 31b and the inner cylinder 36 is a first gas flow path 40 through which heated first gas flow A can flow. In other words, the first gas flow path 40 is arranged to surround the nozzle 31 along its circumferential direction. As shown in Figure 1, the first gas flow path 40 is configured such that the first gas flow A flows through it along the extending direction of the nozzle 31, from the rear end side of the nozzle 31 (i.e., the side of the mixing device 20) toward the tip region 31a. A first gas injection part 40a is connected to the rear end of the first gas flow path 40. The first gas injection part 40a is connected to a first gas supply source (not shown), and is configured to supply the heated first gas flow A supplied from the first gas supply source to the first gas flow path 40. From the viewpoint of convenience, for example, an air flow can be used as the first gas flow A.

[0015] The first gas injection part 40a extends in a direction intersecting the extending direction of the first gas flow path 40. In the embodiment shown in FIG. 1, the extending direction of the first gas injection part 40a and the extending direction of the first gas flow path 40 are substantially orthogonal. Therefore, the first gas flow A supplied from the first gas supply source (not shown) flows through the first gas injection part 40a, and the flow direction is changed by 90 degrees at the connection part between the first gas injection part 40a and the first gas flow path 40, and then flows through the first gas flow path 40. In the device of the present invention, the intersection angle between the first gas injection part 40a and the first gas flow path 40 is not limited to 90 degrees, and the two may intersect at other angles. However, the flow direction of the first gas flow A is changed at least at the connection part between the first gas injection part 40a and the first gas flow path 40.

[0016] As shown in FIG. 1, the spinning unit 30 further includes a second gas flow path 50 for injecting the heated second gas flow B. When the spinning unit 30 is viewed from the extending direction of the nozzle (when viewed from right to left in the drawing, hereinafter referred to as "front"), the second gas flow path 50 is arranged to surround the first gas flow path 40 at a position on the outer periphery rather than the first gas flow path 40, based on the position of the nozzle 31. Further, when the spinning unit 30 is viewed from the front, the second gas flow path 50 is arranged on the inner periphery rather than the electrode 32 and on the outer periphery rather than the first gas flow path 40, based on the position of the nozzle 31. The second gas flow path 50 is a cylindrical space defined by the outer surface of the inner cylinder 36 and the inner surface of the outer cylinder 37. The second gas flow path 50 is configured to inject the heated second gas flow B along the extending direction of the nozzle 31 from the rear end side of the nozzle 31 toward the tip region 31a. A second gas injection unit 50a is connected to the rear end of the second gas flow path 50. The second gas injection unit 50a is connected to a second gas supply source (not shown) and is capable of supplying heated second gas flow B, supplied from the second gas supply source, to the second gas flow path 50. The second gas injection section 50a extends in a direction intersecting the extending direction of the second gas flow path 50. In the embodiment shown in Figure 1, the extending direction of the second gas injection section 50a and the extending direction of the second gas flow path 50 are generally perpendicular. From a convenience standpoint, for example, an airflow can be used as the second gas flow B.

[0017] In the context of the first gas flow A and the second gas flow B, "heated" refers to a gas flow whose temperature is higher than the standard temperature (20°C).

[0018] The electrospinning apparatus 10 may have a collection unit (not shown) for collecting spun fibers at a position opposite the nozzle 31. A collection electrode made of a conductive material such as metal is arranged in the collection unit, and the spun fibers can be collected on the collection unit by the potential difference between the nozzle 31 and the collection electrode. The collection electrode is preferably a flat plate, and it is also preferable that the plate surface of the collection electrode and the direction in which the nozzle 31 extends are substantially perpendicular. The collection electrode is preferably grounded or has a voltage applied to it by a high-voltage power supply. In this case, it is also preferable that a voltage different from the voltage applied to the nozzle 31 is applied to the collection unit. The collection unit may also have a conveying means such as a belt conveyor arranged between the nozzle 31 and the collection electrode. The fibers collected after spinning can be conveyed to downstream processes by the conveying means. If a collection unit is provided, from the viewpoint of fiber collection efficiency, the distance between the tip of the nozzle 31 and the collection unit is preferably set to 50 mm or more, more preferably 100 mm or more, more preferably 2000 mm or less, and even more preferably 1500 mm or less.

[0019] In the electrospinning apparatus having the above configuration, the heated first gas flow A is injected from the first gas channel 40, which is relatively close to the tip region 31a of the nozzle 31, making it easier for the first gas flow A to come into contact with the molten resin discharged from the tip region 31a. As a result, in addition to the Coulomb force, the application of an external force by the injection of the first gas flow makes the stretching of the molten resin more effective, and finer diameter fibers can be produced efficiently. Furthermore, since the heated second gas flow B can be injected from an outer circumference of the first gas channel 40, the ambient temperature around the nozzle 31 in the direction of molten resin discharge can be maintained at a high level, and this ambient temperature can be formed over a wide area. As a result, the cooling and solidification of the molten resin can be delayed, the stretched state of the molten resin can be maintained for a longer period of time, and finer diameter fibers can be produced efficiently. Moreover, the second gas flow B prevents the discharged molten resin or the fibers after cooling and solidification from unintentionally adhering to the electrode 32, allowing the fibers to be transported in the desired direction and increasing production efficiency.

[0020] From the viewpoint of making the above-mentioned effects even more pronounced, it is preferable that the spinning unit 30 is provided with at least an electrically insulating wall portion 35 located on the concave curved surface 32a of the electrode 32 that faces the nozzle 31. This prevents discharge between the nozzle 31 and the electrode 32, allowing for stable fiber spinning.

[0021] The wall portion 35 shown in Figure 1 is in direct contact with the electrode 32 and covers the entire surface of the electrode 32. With this configuration, the wall portion 35 can also function as a support member for the electrode 32. The wall portion 35 has an open end 35c on the tip side of the nozzle 31. The planar shape of the open end 35c of the wall portion 35 may be a perfect circle or an ellipse. Of the wall portion 35, the surface 35b facing the tip area 31a of the nozzle 31 is a concave curved surface on the inner surface of the cylinder.

[0022] The wall portion 35 is preferably made of a dielectric material for electrically insulating the nozzle 31 and the electrode 32. By making the wall portion 35 a dielectric material, the amount of charge on the nozzle 31 can be further increased, making it possible to manufacture even finer diameter fibers. The wall portion 35 may be made of a single type of dielectric material, or it may be a laminate in which multiple types of dielectric materials are stacked.

[0023] In the embodiment shown in Figure 1, the first gas flow A is supplied from a first gas supply source (not shown) to the first gas flow path 40 via the first gas injection unit 40a. As described above, the first gas injection unit 40a and the first gas flow path 40 are generally perpendicular to each other, so the first gas flow A flowing through the first gas injection unit 40a collides with the components constituting the resin supply path 31b in the nozzle 31 at the connection point 40b between the first gas injection unit 40a and the first gas flow path 40, and its flow direction is changed. At that time, some of the heat of the first gas flow A is conducted to the connection point 40b, and that heat is conducted to the molten resin flowing through the resin supply path 31b via the components constituting the resin supply path 31b. As a result, the temperature of the molten resin may rise unintentionally. In particular, if the temperature of the first gas flow A is high, the temperature rise of the molten resin becomes significant, and it may become overheated. This state is illustrated in Figure 2. As shown in Figure 2A, when the temperature of the molten resin is set to 200°C and the temperature of the first gas flow A is set to 350°C, the temperature of the molten resin flowing through the resin supply passage 31b rises rapidly. In this figure, the origin of the horizontal axis represents the position of the connection 40b between the first gas injection section 40a and the first gas flow path 40, and the right end of the horizontal axis represents the position of the tip of the tip region 31a of the nozzle 31.

[0024] When molten resin is overheated, thermal decomposition and oxidation can occur. As a result, carbides are formed in the resin, and foreign matter caused by these carbides may be generated within the molten resin. The generation of foreign matter hinders stable melt spinning. Therefore, in this invention, in order to perform stable melt spinning, the electrospinning apparatus 10 is equipped with means to suppress the generation of foreign matter such as carbides within the molten resin.

[0025] In detail, as shown in Figure 1, the apparatus 10 of this embodiment is provided with an insulating material 60 between the first gas flow path 40 and the resin supply path 31b in the nozzle 31, and at the rear end side in the extending direction of the nozzle 31, along the circumferential direction of the nozzle 31, i.e., the circumferential direction of the resin supply path 31b. The insulating material 60 is arranged to cover the entire outer surface of the resin supply path 31b. As a result, the insulating material 60 is positioned opposite the first gas injection section 40a, as shown in Figure 1, in other words, at least at the position of the connection section 40b between the first gas injection section 40a and the first gas flow path 40. Since the connection section 40b is the point where the molten resin flowing through the resin supply path 31b is heated the most by the first gas flow A, arranging the insulating material 60 at least at the connection section 40b is very advantageous from the viewpoint of suppressing overheating of the molten resin. For example, as shown in Figure 2B, if the temperature of the molten resin is set to 200°C and the temperature of the first gas flow A is set to 350°C, and the insulating material 60 is arranged to cover the outer surface of the resin supply passage 31b as shown in Figure 1, the temperature of the molten resin flowing through the resin supply passage 31b rises more slowly than in the case shown in Figure 2A. In other words, overheating of the molten resin is suppressed.

[0026] The length of the insulating material 60 along the extending direction of the nozzle 31 is preferably set to 10% or more of the total length L of the nozzle 31 starting from the first gas injection section 40a as the starting point S1, from the viewpoint of ensuring an area that is insulated. It is even more preferable to set it to 20% or more from the viewpoint of effectively suppressing overheating of the molten resin flowing through the resin supply passage 31b in the nozzle 31. Furthermore, the length of the insulating material 60 along the extending direction of the nozzle 31 is preferably set to 100% or less, more preferably to 70% or less, and even more preferably to 40% or less, from the viewpoint of suppressing a decrease in resin temperature. The total length L of the nozzle 31 is the distance between the starting point S1 and the ending point S2, where the starting point S1 is the point where the first gas injection section 40a and the first gas flow path 40 intersect, as shown in Figure 1, and the ending point is the tip S2 in the tip region 31a of the nozzle 31.

[0027] As the thermal insulation material 60, a material with low thermal conductivity and high heat resistance is preferably used. Regarding thermal conductivity, it is preferable that the thermal conductivity at room temperature is, for example, 0.25 W / m·K or less. If a material with low thermal conductivity is used, sufficient thermal insulation effect can be expected even if the thermal insulation material 60 is thin. Conversely, even if a material with high thermal conductivity is used, thermal insulation effect can be expected if the thermal insulation material 60 is made thicker. However, making the thermal insulation material 60 thicker is not advantageous from the standpoint of miniaturizing the device 10. Taking these factors into consideration, the product of the thermal conductivity and thickness of the thermal insulation material 60 should be 1.0 × 10⁻⁶. -3 W / K or less, especially 7.0 × 10 -4 W / K or less, especially 5.0 × 10 -4 It is preferable to use a material with a W / K ratio of 0.5 or less.

[0028] The thickness of the insulation material 60 is preferably greater than 0 mm and less than or equal to 10 mm, more preferably between 1 mm and 3 mm, and even more preferably between 1.5 mm and 2.5 mm, provided that the product of the thermal conductivity and thickness is as described above.

[0029] Examples of insulation material 60 include, but are not limited to, glass cloth, laminated boards made by impregnating glass cloth with a heat-resistant binder, glass wool, rock wool, and silica cloth.

[0030] If the first gas flow A is introduced from a position close to the tip of the nozzle 31, it is possible to suppress excessive overheating of the molten resin even without using the insulating material 60. However, since the electrode 32 is located close to the tip of the nozzle 31, it is not easy to introduce the first gas flow A from that position due to the layout of the apparatus. Therefore, in this embodiment, the first gas flow A is introduced from the rear end of the nozzle 31, which is a position with fewer constraints on the layout of the apparatus.

[0031] Figure 3 shows an electrospinning apparatus 10, which is another embodiment of the melt spinning apparatus of the present invention. The apparatus 10 shown in Figure 3 differs from the apparatus shown in Figure 1 in the shape of the electrode 32. Other aspects are the same as those of the apparatus shown in Figure 1, so their explanation is omitted. In Figure 3, the same reference numerals used in Figure 1 are used for the same components as those shown in Figure 1.

[0032] The electrode 32 of the electrospinning apparatus 10 shown in Figure 3 is roughly bowl-shaped and positioned to surround the tip area 31a of the nozzle 31. The surface of the electrode 32 facing the nozzle 31 is formed as a concave curved surface, such as a parabolic surface. The electrode 32 has an open end 32c on the tip side of the nozzle 31, and the planar shape of this open end 32c is circular, such as a perfect circle or an ellipse.

[0033] It is preferable that the concave surface 32a, which consists of a parabolic surface or the like, is curved at all positions. Here, a curved surface means either (a) a curved surface that has no planar portion at all, (b) a shape that can be considered as a whole to be a concave surface by connecting multiple segments that have planar portions, or (c) a shape that can be considered as a whole to be a concave surface by connecting multiple annular segments that have a strip-shaped portion in which one of three mutually orthogonal axes does not have curvature.

[0034] From the viewpoint of facilitating the concentration of electric charge in the tip region 31a of the nozzle 31 and increasing the amount of charge in the discharged molten resin, it is preferable that the concave curved surface 32a is formed such that the normal to it at any position passes through the tip of the tip region 31a or its vicinity, and it is even more preferable that the concave curved surface 32a has the same shape as the inner surface of a spherical shell. Similarly, it is also preferable that the open end 32c is perfectly circular.

[0035] It is preferable that the concave curved surface 32a of the electrode 32, which faces the tip area 31a of the nozzle 31, is provided with an electrically insulating wall portion 35. This prevents discharge between the nozzle 31 and the electrode 32, allowing for stable fiber spinning. It is preferable that the wall portion 35 is in direct contact with the electrode 32 and covers the entire surface of the electrode 32. The wall portion 35 has an open end 35c on the tip side of the nozzle 31. The planar shape of the open end 35c of the wall portion 35 may be a perfect circle or an ellipse. Of the wall portion 35, the surface facing the tip area 31a of the nozzle 31 forms a wall surface 35b that slopes toward the open end 35c side. The electrode 32 provided in the apparatus 10 of this embodiment has the advantage of being able to concentrate the charge on the tip region 31a of the nozzle 31 more easily than the electrode in the apparatus shown in Figure 1, thus making it easier to charge the molten resin discharged from the tip region 31a.

[0036] The apparatus 10 of this embodiment, similar to the apparatus shown in Figure 1, is equipped with a heat insulating material 60 along the circumferential direction of the resin supply passage 31b of the nozzle 31, located between the first gas flow path 40 and the nozzle 31, and at the rear end of the nozzle 31 in the direction of extension. Therefore, with the apparatus 10 of this embodiment, overheating of the molten resin flowing through the resin supply passage 31b is suppressed, thereby suppressing the generation of foreign matter such as carbides. As a result, melt spinning can be performed stably.

[0037] Incidentally, the temperatures of the heated first gas flow A and second gas flow B are preferably changed as appropriate depending on the type of raw material resin used in the present invention and its melting point, as described later. In other words, if the type of raw material resin used is changed, it is preferable to change the temperatures of each gas flow A and B to temperatures suitable for the raw material resin. On the other hand, from the viewpoint of more effectively suppressing overheating of the molten resin, it is desirable to change the length of the insulating material 60 and the material used for the insulating material 60 to conditions appropriate for suppressing overheating of the molten resin each time the temperatures of each gas flow A and B are changed. Therefore, in order to simplify the operation of the electrospinning apparatus even when the type of raw material resin is frequently changed, another embodiment can be considered. In the electrospinning apparatus 10, which is yet another embodiment of the melt spinning apparatus of the present invention shown in Figure 4, in order to easily suppress overheating of the molten resin, in addition to the heat insulating material 60, means for controlling the temperature of the molten resin regardless of the temperature of each gas flow A and B are provided.

[0038] In detail, the electrospinning apparatus 10 of this embodiment differs from the apparatus shown in Figure 1 in that it includes a heater 70, a heat pipe 71, and a housing (not shown) that accommodates the heat pipe 71 near the nozzle 31. Other aspects are the same as those of the apparatus shown in Figure 1, so their explanation is omitted. Also, in Figure 4, the same reference numerals used in Figure 1 are used for the same components as those shown in Figure 1.

[0039] The electrospinning apparatus 10 shown in Figure 4 is equipped with a heater 70 between the nozzle 31 and the heat insulating material 60. The heater 70 is used to heat the molten resin flowing through the resin supply passage 31b in the nozzle 31. The heater 70 is configured to heat or maintain a temperature above the melting point of the raw material resin used in the present invention. The heater 70 is positioned directly below the nozzle 31 and straddles the nozzle 31. The heater 70 is positioned such that its front end 70a is located behind the rear end of the electrode 32. By arranging the heater 70 in this manner, it is possible to prevent the heater 70 from short-circuiting due to dielectric breakdown, thereby reducing the distance between the electrode 32 to which a high voltage is applied during the operation of the electrospinning apparatus 10 and the heater 70. Incidentally, since dielectric breakdown can be prevented even when an insulated heater is used, the distance between the electrode 32 and the heater can be brought closer together. In this case as well, by arranging the heater 70 as described above, the effects of thermal stress caused by repeated operation and stopping of the electrospinning apparatus 10 can be prevented, and in addition to short circuits of the heater 70 caused by dielectric breakdown, the destruction of the insulating material used for the insulating treatment can also be prevented. From the viewpoint of miniaturizing the electrospinning apparatus 10, the rear end 70b of the heater 70 is positioned at least forward of the starting point S1. As the heater 70, electric heaters such as panel heaters, ceramic heaters, and PTC heaters can be used.

[0040] The electrospinning apparatus 10 of this embodiment is equipped with a heat pipe 71 between the heater 70 and the nozzle 31, extending along the direction of extension of the nozzle 31. The heat pipe 71 is closed at both ends and has a capillary structure called a wick on its inner wall. A small amount of working fluid, such as pure water, is contained inside the heat pipe 71. The inside of the heat pipe 71 is under vacuum to prevent the ingress of substances other than the working fluid and the water vapor generated from the working fluid. First, when heat generated from the heater 70 is conducted to the heat pipe 71, the working fluid present near the heated portion of the heat pipe 71 evaporates, generating water vapor. Next, the generated water vapor moves through the inside of the heat pipe 71 to the lower temperature portion of the heat pipe 71. After that, the moved water vapor condenses, releasing heat and changing into a liquid. By utilizing this process, the heat pipe 71 is configured to smoothly conduct heat generated from the heater 70 to the tip of the nozzle 31 along the direction of extension of the nozzle 31 without the use of a power source. Therefore, the heat pipe 71 is made of a material that has thermal conductivity.

[0041] The heat pipe 71 is entirely housed inside the casing. That is, the heat pipe 71, while housed in the casing, is positioned between the heater 70 and the nozzle 31, along the direction in which the nozzle 31 extends. The casing is made of a material with high thermal conductivity. For example, the casing can be made from a metal block. The casing containing the heat pipe 71 is positioned so as to be in contact with both the nozzle 31 and the heater 70, with one pipe above and one below the nozzle 31, along the direction in which the nozzle 31 extends. This arrangement of the heat pipe 71 allows for efficient conduction of heat generated from the heater 70 to the tip of the nozzle 31.

[0042] With the electrospinning apparatus 10 having this configuration, the temperature of the molten resin flowing through the resin supply passage 31b in the nozzle 31 can be controlled by controlling the heater 70, which generates heat from the heater 70. As a result, even when the type of raw material resin is changed, it is not necessary to change the temperature of each gas flow A and B to a temperature suitable for the raw material resin each time. This is because the heating by the heater 70 plays a part in controlling the temperature of the molten resin flowing through the resin supply passage 31b in the nozzle 31. As a result, with the electrospinning apparatus 10 of this embodiment, it is not necessary to change the length of the insulating material 60 each time the type of raw material resin is changed so that each gas flow A and B reaches the desired temperature, which is a cumbersome operation, and thus overheating of the molten resin can be easily suppressed.

[0043] From the viewpoint of efficiently controlling the temperature of the molten resin flowing through the resin supply passage 31b in the nozzle 31, the distance between the rear end 70b of the heater 70 and the starting point S1 is preferably set to 0 mm or more and 20 mm or less, more preferably to 10 mm or less, and even more preferably to 2 mm or less. From a similar viewpoint, the length of the heater 70 along the extending direction of the nozzle 31 is preferably set to 10% or more and 50% or less of the total length L of the nozzle 31, more preferably to 25% or less, and even more preferably to 20% or less. From a similar viewpoint, the length of the heat pipe 71 along the extending direction of the nozzle 31 is preferably set to 50% or more and 100% or less of the total length L of the nozzle 31, more preferably to 70% or more, and even more preferably to 90% or more. From the viewpoint of significantly simplifying the operation of the electrospinning apparatus, it is preferable to have the heater 70, and more preferably the heater 70 and heat pipe 71, perform the heating or keeping the raw resin above its melting point, rather than the heated gas flows A and B. For this reason, it is preferable that the insulating material 60 along the extending direction of the nozzle 31 has a length that covers the entire length of the resin supply passage 31b, starting from the first gas injection section 40a as the starting point S1.

[0044] Next, we will describe matters that are applicable to all of the embodiments described above. The inner diameter of the tip region 31a of the nozzle 31 is preferably 50 μm or more, more preferably 100 μm or more, preferably 3000 μm or less, and even more preferably 2000 μm or less. By setting the inner diameter of the tip region 31a within this range, molten resin can be easily and quantitatively discharged. The inner diameter of the resin supply passage 31b in the nozzle 31 can be the same as or larger than the inner diameter of the tip region 31a.

[0045] The gap D1 of the first gas flow path 40 (see Figure 1) is preferably 1 mm or more, more preferably 2 mm or more, preferably 10 mm or less, and even more preferably 7 mm or less. The gap D2 of the second gas flow path 50 (see Figure 1) is preferably 10 mm or more, more preferably 20 mm or more, preferably 100 mm or less, and even more preferably 70 mm or less. By having each gap within these ranges, the first gas flow A and the second gas flow B can be adjusted to the desired wind speed and airflow rate, further increasing the stretching efficiency of the molten resin.

[0046] From the viewpoint of successfully supplying molten resin from the kneading device 20, it is preferable that a heating means (not shown) for heating or maintaining the temperature of the molten resin is provided between the kneading device 20 and the spinning unit 30. Known means such as a heater can be used as the heating means. It is preferable that the temperature to be heated or maintained is above the melting point of the raw material resin used in the production of the fibers. This heater has a different role and is located in a different position from the heater shown in Figure 4 described above. Furthermore, the resin supply path 31b is preferably made of metal, for example, from the viewpoint of thermal conductivity and mechanical strength, and is preferably grounded from the viewpoint of preventing voltage load on the kneading device 20 in the molten electrospinning method.

[0047] The terminal positions of the first gas channel 40 and the second gas channel 50 in the spinning unit 30 are not particularly limited insofar as the effects of the present invention are achieved. However, when the position of the tip in the tip region 31a of the nozzle 31 is used as a reference (zero), the forward position of the nozzle 31 is represented by a positive value, and the rear position of the nozzle 31 is represented by a negative value, the terminal positions of each gas channel are preferably in the range of -50 mm to +15 mm, independently of each other. The terminal position of each gas channel is the position of the front end of the outer member constituting each gas channel, with the position of the nozzle 31 as the reference when the spinning unit 30 is viewed from the front. Furthermore, the terminal position of the first gas channel 40 is preferably the same as the position of the tip in the tip region 31a of the nozzle 31, or located forward of the tip, and the terminal position of the second gas channel 50 is preferably the same as the position of the tip in the tip region 31a of the nozzle 31, or located rearward of the tip.

[0048] Examples of dielectric materials used in the wall portion 35 include ceramic materials such as mica, alumina, zirconia, and barium titanate, which are insulating materials, and resin materials such as bakelite (phenol resin), nylon (polyamide), polytetrafluoroethylene, and polyphenylene sulfide. Other examples include glass cloth, laminates made by impregnating glass cloth with a heat-resistant binder, glass wool, rock wool, and silica cloth. Of these, it is preferable to use at least one insulating material selected from alumina, bakelite, glass cloth, laminates made by impregnating glass cloth with a heat-resistant binder, glass wool, rock wool, and silica cloth, and it is particularly preferable to use a laminate made by impregnating glass cloth with a heat-resistant binder.

[0049] The thickness of the dielectric material used in the wall portion 35 is preferably 0.8 mm or more, and more preferably 8 mm or more, from the viewpoint of increasing the charge amount of the molten resin. This thickness refers to the thickness of the wall portion 35 when the wall portion 35 is composed of one or more types of dielectric material (i.e., the thickness of the dielectric material is equal to the thickness of the wall portion 35). Furthermore, if the wall portion 35 is a composite material containing metal particles or a layer of air inside (the part not exposed on the surface), this refers to the thickness of the dielectric material only, obtained by subtracting the sum of the thickness of the metal particle size or the thickness of the air layer in the thickness direction of the wall portion 35 from the thickness of the wall portion 35. Depending on the size of the electrode 32 and the positional relationship between the nozzle 31 and the electrode 32, it is preferable that the thickness of the wall portion 35 is such that the nozzle 31 and the wall portion 35 do not come into direct contact.

[0050] The above was a description of the electrospinning apparatus 10. Below, the method for manufacturing fibers using the apparatus 10, i.e., the electrospinning method, will be described. In the method for manufacturing fibers using the electrospinning apparatus 10, an electric field is generated between the nozzle 31 and the electrode 32, and molten resin is discharged from the tip region 31a of the nozzle 31 while a first gas flow A and a second gas flow B are injected. The discharged molten resin is finely divided as it is stretched three-dimensionally by the Coulomb force generated inside it and the injection of the first gas flow A and the second gas flow B, and at the same time, the cooling and solidification of the resin proceeds, forming fine-diameter fibers.

[0051] The fibers produced by the method of the present invention are small fibers called nanofibers, with a fiber diameter of 30 μm or less when expressed as an equivalent circular diameter. The nanofibers preferably have a fiber diameter of 0.1 μm or more, preferably 10 μm or less, more preferably 5 μm or less, and even more preferably 3 μm or less.

[0052] The fiber diameter of a fiber can be measured, for example, by selecting 500 fibers arbitrarily from a two-dimensional image obtained by scanning electron microscopy, removing defects such as spun fiber clumps, fiber intersections, and polymer droplets, and directly reading the length of a line drawn perpendicular to the longitudinal direction of the fiber as the fiber diameter. The median diameter is determined from the distribution of the measured fiber diameters and this is referred to as the fiber diameter in this specification.

[0053] In the manufacturing of fibers, when injecting the first gas flow A and the second gas flow B, it is preferable to inject the first gas flow A at a velocity equal to or greater than that of the second gas flow B. By adjusting the velocity of each gas flow, the discharged molten resin can be stretched more strongly by the external force generated by the injection of the first gas flow, and as a result, even finer diameter fibers can be efficiently obtained.

[0054] More specifically, the ratio (A1 / B1) of the wind speed A1 of the first gas flow A to the wind speed B1 of the second gas flow B is preferably 1 or more, more preferably 5 or more, preferably 100 or less, and more preferably 80 or less.

[0055] The wind velocity A1 of the first gas flow A is preferably 20 m / s or more, more preferably 30 m / s or more, and even more preferably 100 m / s or more, from the viewpoint of further stretching the discharged molten resin, and is practically 300 m / s or less, from the viewpoint of preventing unintended breakage during the stretching of the molten resin. Similarly, the wind velocity B1 of the second gas flow B is preferably 1 m / s or more, more preferably 2 m / s or more, preferably 30 m / s or less, and even more preferably 25 m / s or less, provided that the above ratio is satisfied. These wind velocities are the values ​​at the end of each gas flow path 40, 50. These wind velocities can be adjusted as appropriate, for example, by changing the pressure of the gas flow supplied from each gas source or by changing the gap of each gas flow path.

[0056] In the manufacturing of fibers, when injecting the first gas flow A and the second gas flow B, it is also preferable to inject the second gas flow B at a rate equal to or greater than that of the first gas flow A. By adjusting the airflow rates of each gas flow, the temperature of the space around the nozzle 31 in the discharge direction of the molten resin can be maintained at a high level, and this space can be formed over a wider area. As a result, the stretched state of the molten resin can be maintained for a long time, and the cooling and solidification of the molten resin can be delayed, enabling the efficient production of even finer diameter fibers.

[0057] More specifically, the ratio of the airflow rate B2 of the second gas flow B to the airflow rate A2 of the first gas flow A (B2 / A2) is preferably 1 or more, more preferably 2 or more, even more preferably 5 or more, preferably 200 or less, more preferably 100 or less, and even more preferably 20 or less.

[0058] The airflow rate A2 of the first gas flow A is preferably 10 L / min or more, more preferably 60 L / min or more, more preferably 300 L / min or less, and more preferably 200 L / min or less, from the viewpoint of achieving both improved stretching efficiency and prevention of breakage of the discharged molten resin. Similarly, the airflow rate B2 of the second gas flow B is preferably 100 L / min or more, more preferably 500 L / min or more, more preferably 4000 L / min or less, and more preferably 3000 L / min or less, provided that the above ratio is satisfied. These airflow rates are the values ​​at the end of each gas injection port. These airflow rates can be adjusted as appropriate, for example, by changing the flow rate of the gas flow supplied from each gas supply source or by changing the gap of each gas flow path.

[0059] In particular, from the viewpoint of maintaining a higher ambient temperature in the tip region 31a of the nozzle 31 in the discharge direction of the molten resin, thereby increasing the stretching efficiency of the molten resin and producing even finer diameter fibers, it is also preferable to inject a second gas stream B that is at a temperature higher than the solidification temperature of the molten resin used. The solidification temperature of the molten resin refers to the melting point of the resin composition containing the thermoplastic resin, which will be described later.

[0060] The temperatures of the heated gas flows A and B can be appropriately changed depending on the type of raw material resin and its melting point, but the temperature of the first gas flow A is preferably 100°C or higher, more preferably 200°C or higher, preferably 500°C or lower, and more preferably 400°C or lower. The temperature of the second gas flow B is preferably lower than the temperature of the first gas flow A, specifically preferably 25°C or higher, more preferably 100°C or higher, preferably 300°C or lower, and even more preferably 200°C or lower. These temperatures are the values ​​at the end of each gas flow path. These temperatures can be appropriately adjusted, for example, by changing the degree of heating at each gas supply source.

[0061] In the method for manufacturing fibers using the electrospinning apparatus 10 of the embodiment shown in Figures 1 and 3, in order to suppress overheating of the molten resin flowing through the resin supply passage 31b in the nozzle 31, it is preferable to spin the fibers such that the value of Tn / Tp is 0.98 or less, particularly 0.94 or less, and especially 0.93 or less, when the temperature of the molten resin discharged from the tip region 31a of the nozzle 31 is Tp (°C), and the temperature of the molten resin flowing through the nozzle 31 at a position 80% of the total length L of the nozzle 31, with the first gas injection section 40a as the starting point S1 (see Figure 1). This is because it is desirable from the viewpoint of preventing overheating that the temperature of the molten resin does not reach the discharge temperature earlier than the temperature of the molten resin when it is discharged. However, on the other hand, if the value of Tn / Tp becomes large, the temperature of the molten resin discharged from the tip region 31a of the nozzle 31 also becomes low, and it may become difficult to reduce the diameter of the fibers. Therefore, the value of Tn / Tp is preferably 0.9 or greater, more preferably 0.91 or greater, and even more preferably 0.92 or greater. In order to set the value of Tn / Tp within this range, the material, thickness, and length of the insulation material 60 should be appropriately adjusted. The reason for measuring the temperature at the 80% position is that it is a value that can be measured in a round number beyond the 70% position, which is preferably set as the length of the insulation material.

[0062] Similarly, in the method for manufacturing fibers using the electrospinning apparatus 10 of the embodiments shown in Figures 1 and 3, in order to suppress overheating of the molten resin flowing through the resin supply passage 31b in the nozzle 31, spinning is performed such that the value of (Tp-Tm) / (L1-L2) is preferably greater than 0.35, more preferably 0.38 or higher, and even more preferably 0.55 or higher. In the above formula, Tp is the temperature (°C) of the molten resin discharged from the tip region 31a of the nozzle 31, as described above. Tm is the temperature (°C) of the molten resin flowing through the nozzle 31 at the center of the total length L of the nozzle 31, with the first gas injection section 40a as the starting point S1 (see Figure 1). L1 is the distance from the starting point S1 (see Figure 1) to the tip of the nozzle 31, relative to the total length L of the nozzle 31, with the starting point S1 being the first gas injection section 40a. L2 is the distance from the first gas injection section 40a, which is the starting point S1, to the center of the total length L of the nozzle 31.

[0063] A larger value of (Tp-Tm) / (L1-L2) is advantageous in terms of suppressing overheating of the molten resin, but on the other hand, it may become more difficult to reduce the diameter of the fibers. Therefore, the value of (Tp-Tm) / (L1-L2) is preferably 0.8 or less, more preferably 0.77 or less, and even more preferably 0.6 or less. In order to set the value of (Tp-Tm) / (L1-L2) within this range, the material, thickness, and length of the insulation material 60 should be appropriately adjusted.

[0064] The molten resin used in the present invention is a fluid resin composition containing a thermoplastic resin having a melting point. "Having a melting point" means that, in differential scanning calorimetry (DSC), when the resin is heated, it exhibits an endothermic peak due to a phase change from solid to liquid before thermal decomposition of the resin. The melting point of the thermoplastic resin can be measured, for example, using a melting point / dropping point analyzer (Mettler Toledo, model: DP90 automatic dropping point / softening point analyzer) in accordance with JIS K 0064 or JIS K 2220.

[0065] Examples of thermoplastic resins include polyolefin resins such as polyethylene, polypropylene, and ethylene-α-olefin copolymer; polyester resins such as polyethylene terephthalate and polybutylene terephthalate, polylactic acid, and liquid crystal polymers; polyamide resins such as nylon 6 and nylon 66; vinyl polymers such as polyvinyl chloride, polyvinylidene chloride, and polystyrene; acrylic polymers such as polyacrylic acid, polyacrylic acid esters, polymethacrylic acid, and polymethacrylic acid esters; and polyvinyl acetate and polyvinyl acetate-ethylene copolymers. These resins can be used individually or in combination of two or more. Of these thermoplastic resins, polyolefin resins such as polyethylene, polypropylene, and ethylene-α-olefin copolymer are preferred because they are easy to spin due to their properties such as low melting point, high fluidity, and high ductility.

[0066] The molten resin may be a resin composition containing additives in addition to a thermoplastic resin, as long as the effects of the present invention are not impaired. Examples of additives include antistatic agents, antioxidants, neutralizing agents, light stabilizers, ultraviolet absorbers, lubricants, antistatic agents, metal deactivators, and hydrophilic agents. Examples of antistatic agents include metal soaps in which organic acids such as stearic acid, lauric acid, and ricinoleic acid form metal salts with metals such as Ca, Li, Zn, and Ba, as well as ionic surfactants such as acylalkyl taurine salts, alkyl sulfonates, and quaternary ammonium salts. Examples of antioxidants include phenolic antioxidants, phosphite antioxidants, and thio antioxidants. Examples of neutralizing agents include higher fatty acid salts such as calcium stearate and zinc stearate. Examples of light stabilizers and ultraviolet absorbers include hindered amines, nickel complex compounds, benzotriazoles, and benzophenones. Examples of lubricants include higher fatty acid amides such as stearate amide. Examples of antistatic agents include fatty acid partial esters such as glycerol fatty acid monoesters. Examples of metal deactivators include phosphores, epoxy compounds, triazoles, hydrazides, and oxamides. Examples of hydrophilic agents include polyhydric alcohol fatty acid esters, ethylene oxide adducts, and nonionic surfactants such as amine anamides.

[0067] When the molten resin contains additives, the additive content is preferably 0.5% to 50% by mass, more preferably 1% to 40% by mass, and even more preferably 3% to 30% by mass, from the viewpoint of successfully performing electrospinning. In other words, the molten resin used in the production of nanofibers of the present invention is mainly a thermoplastic resin.

[0068] There are no particular restrictions on the method for producing the molten resin. For example, it can be produced by heating and melting a thermoplastic resin, adding additives as needed, and then heating and kneading the mixture. Such a molten resin may be produced by pre-melting and kneading it as a masterbatch, or the thermoplastic resin and additives as needed may be supplied to a kneading device 20 at the time of production, and then heated, melted, and kneaded within the kneading device 20.

[0069] In the fiber manufacturing method described above, for the sake of explanation, a configuration in which an electrospinning apparatus 10 equipped with one spinning unit 30 is used alone has been described, but the present invention is not limited to this configuration. In detail, electrospinning may be performed using multiple electrospinning apparatuses 10 equipped with one spinning unit 30, or electrospinning may be performed using one or more electrospinning apparatuses 10 equipped with multiple spinning units 30 (hereinafter, these configurations are collectively referred to as "multiple configurations"). In particular, by arranging the electrospinning apparatuses 10 or spinning units 30 in close proximity and performing electrospinning in that state, even when the airflow rate B2 of the second gas flow is reduced, the temperature of the space around and in front of the nozzle 31 can be maintained at a high level, and the space can be formed over an even wider area. As a result, the cooling and solidification of the molten resin can be delayed, and finer diameter fibers can be manufactured more effectively. In addition, since fibers can be manufactured at once using multiple spinning units 30, there is also the advantage that the cost of supplying the heated gas flow can be reduced while further increasing the fiber production efficiency.

[0070] The arrangement of the multiple electrospinning apparatus 10 or spinning units 30 can be appropriately selected according to the manufacturing environment and the intended use of the fibers to be manufactured. For example, when viewing the spinning units 30 from the front, the multiple spinning units 30 may be arranged in one or more rows aligned in one direction, or adjacent spinning units 30 may be arranged alternately in front of and behind each other in the conveying direction in the collection section.

[0071] In the above-described multiple-arrangement configuration, the airflow rate B2 of the second gas flow B is preferably 50 L / min or more, more preferably 100 L / min or more, more preferably 2000 L / min or less, and more preferably 1500 L / min or less, provided that it satisfies the airflow rate A2 and B2 / A2 ratio of the first gas flow A described above. If the airflow rate B2 in the multiple-arrangement configuration is within this range, the discharged molten resin can be sufficiently stretched, and the reduction in fiber diameter can be efficiently achieved. This airflow rate B2 is the value at the end of the gas injection port and can be adjusted as appropriate, for example, by changing the flow rate of the gas flow supplied from the gas supply source or by changing the gap of each gas flow path.

[0072] Nanofibers or their deposits produced by the electrospinning method using the electrospinning apparatus 10 described above can be used for various purposes as a fibrous molded body formed by accumulating them. Examples of molded body shapes include sheets, cotton-like bodies, and thread-like bodies. The fibrous molded body may be used by laminating it with other sheets or by incorporating various liquids, fine particles, fibers, etc. Fiber sheets are suitably used as sheets attached to human skin, teeth, gums, hair, the skin, teeth, gums of non-human mammals, and the surfaces of plants such as branches and leaves for non-medical purposes such as medical, cosmetic, and decorative purposes. They are also suitably used as high-performance filters with high dust collection and low pressure loss, battery separators that can be used at high current densities, and cell culture substrates with a highly porous structure. Cotton-like fibrous bodies are suitably used as soundproofing materials and heat insulating materials.

[0073] Although the present invention has been described above based on its preferred embodiments, the present invention is not limited to the above embodiments. For example, the apparatus 10 of the above embodiment had gas flow paths 40 and 50 through which two types of gas flows, a first gas flow A and a second gas flow B, flowed. Alternatively, the apparatus 10 may have only a single gas flow path through which only the first gas flow A flows. Or, in some cases, the apparatus 10 may have gas flow paths through which other gas flows flow in addition to the gas flow paths 40 and 50 through which two types of gas flows, the first gas flow A and the second gas flow B, flow.

[0074] Furthermore, although the apparatus 10 of the above embodiment was equipped with a cylindrical or substantially bowl-shaped electrode 32, other shapes can be used as the electrode 32, as long as they can impart an electric charge to the molten resin being discharged.

[0075] Furthermore, although the electrospinning apparatus 10 shown in Figure 4 is equipped with a heater 70 and a heat pipe 71, the apparatus 10 may instead be equipped with only a heater 70 and without a heat pipe 71. [Examples]

[0076] The following shows the results of a simulation of the melt spinning apparatus of the present invention.

[0077] [Simulation conditions] Distance from resin inlet to discharge port: 160mm Spinning rate: 1g / min Resin material: Polypropylene Inlet resin temperature: 200℃ Density of resin material: 0.9 g / cm³ 3 Thermal conductivity of insulation material × thickness: 5.0 × 10 -4 (W / K) Heat source: First gas flow A Temperature of the first gas flow A: 350℃ Flow rate of the first gas flow A: 180 L / min

[0078] 〔evaluation〕 Figure 4 shows the results of temperature plots at L0, L30, L50, and L70, with the distance from the resin inlet on the horizontal axis and the resin temperature on the central axis on the vertical axis. L70 means that the insulation material is placed along the total length L of the nozzle 31, starting from the first gas injection section 40a, up to a length of 70 mm. The same applies to L30 and L50, meaning that the insulation material is placed up to lengths of 30 mm and 50 mm, respectively. L0 means that no insulation material is placed. When expressed as a percentage of the total length L of the nozzle 31, starting from the first gas injection section 40a, L70 means that the insulation material is placed up to a length of 53%. If the same notation is used for L30 and L50, L30 is 23% and L50 is 38%.

[0079] As is clear from the results shown in Figure 5, the simulation results showed that the temperature rise was suppressed more effectively in the cases of L30, L50, and L70, which use insulation, compared to the case of L0, which does not use insulation. Based on these results, it is considered that the generation of carbides will be suppressed if actual spinning is carried out under the above simulation conditions. [Explanation of symbols]

[0080] 10. Electrospinning apparatus 31 nozzles 40 First gas flow path 40a First gas injection section 50 Second gas flow path 50a Second gas injection section 60 Insulation

Claims

1. a nozzle for discharging molten resin; a gas flow path disposed to surround the nozzle along its circumferential direction; a gas injection unit connected to the gas flow path and supplying a heated gas flow to the gas flow path; A melt spinning apparatus comprising: the gas flow path is configured so that the heated gas flow circulates from a rear end of the nozzle toward a front end of the nozzle along an extension direction of the nozzle, a heat insulating material disposed between the gas flow path and the nozzle and along a circumferential direction of the nozzle at a position on the rear end side of the nozzle in an extending direction of the nozzle;

2. The melt spinning apparatus according to claim 1 , wherein the gas injection part extends in a direction intersecting with an extending direction of the nozzle.

3. The melt spinning apparatus according to claim 1 or 2, wherein the heat insulating material is provided at a position facing the gas injection part.

4. 3. The melt spinning apparatus according to claim 1, wherein the length of the insulating material along the extension direction of the nozzle is 10% to 100% of the total length of the nozzle starting from the gas injection portion.

5. The product of the thermal conductivity and thickness of the heat insulating material is 1.0 × 10 －３ 3. The melt spinning apparatus according to claim 1, wherein the melt spinning rate is 1 / 2 W / K or less.

6. The melt spinning apparatus according to claim 1 or 2, further comprising a heater between the nozzle and the insulating material.

7. The melt spinning apparatus according to claim 6, further comprising a heat pipe extending along the extension direction of the nozzle between the heater and the nozzle.

8. A method for producing fibers using the melt spinning apparatus according to claim 1 or 2.

9. A method for producing a fiber using the melt spinning apparatus according to claim 1 or 2, the temperature of the molten resin discharged from the nozzle is Tp, When the temperature of the molten resin flowing through the nozzle at a position 80% of the total length of the nozzle starting from the gas injection portion is Tn, A manufacturing method in which spinning is carried out so that Tn / Tp is 0.98 or less.

10. A method for producing a fiber using the melt spinning apparatus according to claim 1 or 2, the temperature of the molten resin discharged from the nozzle is Tp, With respect to the entire length of the nozzle starting from the gas injection portion, the temperature of the molten resin flowing through the nozzle at the center position of the entire length is defined as Tm, With respect to the total length of the nozzle starting from the gas injection portion, the distance from the starting point to the tip of the nozzle is defined as L1, When the distance from the gas injection portion to the center position of the entire length of the nozzle is L2, A manufacturing method in which spinning is carried out so that the value of (Tp-Tm) / (L1-L2) exceeds 0.35.

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