Fiber production device and fiber production method

Abstract

The present invention provides a fiber production device in which one fibrous polymer after discharge is stretched by revolving at a high speed, said being characterized by having a structure in which an air flow closing member has, in a cross-section perpendicular to the polymer discharge direction at a position immediately after polymer discharge, a cross-sectional area that continuously or incrementally increases toward the downstream side in the polymer discharge direction.

Description

Fiber manufacturing apparatus and fiber manufacturing method

[0001] The present invention relates to a fiber manufacturing apparatus and a fiber manufacturing method.

[0002] In recent years, thinning (fine fineness) of fibers has been demanded in many fields, and various research and developments have been conducted on methods of discharging a thermoplastic polymer from a spinneret in a fibrous form and stretching it, and these methods have been implemented using several stretching apparatuses. As general stretching methods, there are methods of generating a speed difference in the fiber by rotating a roller while the fiber is in contact with the fiber after discharge, and methods of applying tension to the fiber by injecting a high-speed air flow into the traveling fiber and using the frictional force generated between the fiber and the air flow.

[0003] Patent Document 1 discloses a method of stretching a fiber while applying a rotational force to the polymer immediately after discharge from a die. In this fiber stretching method, a torsional force or a centrifugal force is generated in the fiber stretching portion, increasing the stretching force applied to the fiber, so that the fiber can be thinned.

[0004] Patent Document 2 discloses a method of stretching a fiber formed by discharging a fluid in which a difficult-to-fiberize substance is surrounded by an easily fiberizable substance from a die, by ejecting a gas jet from three or more nozzles arranged around the outlet of the discharge hole to form a swirling flow around the fiber. In this fiber stretching method, the fiber is stretched by swirling the fiber after discharge, and the difficult-to-fiberize substance can be fiberized.

[0005] As another method of stretching a fiber with a swirling flow, Patent Document 3 discloses a method of providing a tubular fiber spinning needle having an inlet for introducing a polymer solution and an outlet for discharging the polymer solution, and ejecting a compressed gas jet from the inlet to discharge the polymer from the outlet in a state where the outlet of the spinning needle is vibrated or rotated. In this fiber stretching method, a centrifugal force acting on the polymer solution is generated by the vibration or rotation of the outlet of the spinning needle, the polymer solution is divided into droplets at the outlet, and the droplets are stretched by the jet of the compressed gas to obtain polymer fibers.

[0006] Patent Document 4 discloses a method for stretching fibers using a high-speed airflow, in which hot air is blown from an inclined channel into a parallel channel, the hot air is straightened in the parallel channel relative to the flow of molten resin, and the straightened hot air is blown onto the molten resin. In this fiber stretching method, the yarn can be stretched stably without the yarn being disturbed by the hot air.

[0007] International Publication No. 2023 / 181740, Japanese Patent Publication No. Sho 60-119212, Japanese Patent Publication No. 2022-32977, Japanese Patent Publication No. 2011-241509

[0008] Patent Document 1 describes a configuration in which a rotational force is applied to the fibers after discharge using a swirling flow to rotate the yarn. However, when the yarn is rotated at high speed by the swirling flow, the yarn may revolve. Patent Document 1 also discloses a configuration in which an airflow closure member is installed downstream of the discharge section of the nozzle. In this configuration with an airflow closure member, if the yarn revolves, there is a concern that the yarn may adhere to the wall of the airflow closure member and break.

[0009] In the fiber stretching method described in Patent Document 2, a linear jet of gas is injected directly into an open space from a nozzle. As a result, the gas expands before it can form a swirling flow, and the velocity of the airflow decreases before it collides with the fibers. Therefore, the swirling speed of the fibers cannot be increased, resulting in a low swirling speed and an insufficient reduction in fiber diameter.

[0010] In the fiber stretching method described in Patent Document 3, the location where the compressed gas jet is injected and the outlet of the spinning nozzle that discharges the polymer are far apart. Therefore, it is not possible to directly apply a twisting force to the polymer discharged from the spinning nozzle using the compressed gas jet. As a result, the stretching effect achieved by twisting the fiber cannot be fully obtained. Furthermore, because the area between the location where the compressed gas jet is injected and the outlet of the spinning nozzle is not sealed, the compressed gas jet slows down near the outlet, preventing sufficient fiber stretching.

[0011] In the fiber manufacturing method described in Patent Document 4, the fibers are stretched solely by the frictional force generated between the polymer and the parallel airflow. Increasing the frictional force requires increasing the airflow, but as the airflow increases, yarn oscillation occurs, and the section in which frictional force is generated shrinks. Therefore, it is difficult to increase the frictional force, and the fibers cannot be stretched sufficiently.

[0012] The present invention provides a fiber manufacturing apparatus and manufacturing method that can stably produce fibers with a very small diameter by stretching a fibrous polymer extruded from the discharge hole of a die while rotating it at high speed in a state where the polymer is easily deformed before solidification.

[0013] [1] The present invention, which solves the above problems, is an apparatus for producing fibers by stretching a fibrous polymer, comprising: a nozzle having a discharge hole for discharging the fibrous polymer; an airflow closure member surrounding a space through which the fibrous polymer passes, downstream of the discharge hole in the polymer discharge direction; and an airflow nozzle for injecting airflow into the space surrounded by the airflow closure member, wherein the cross-sectional area of ​​the space surrounded by the airflow closure member in a cross section perpendicular to the polymer discharge direction increases continuously or stepwise toward the downstream side in the polymer discharge direction, and the jet flow injected from the airflow nozzle into the space surrounded by the airflow closure member forms a swirling flow toward the downstream side in the polymer discharge direction in the space, and rotates the fibrous polymer with the swirling flow around a straight line extending from the center of the discharge hole in the polymer discharge direction.

[0014] The fiber manufacturing apparatus of the present invention is preferably in the form of [2] or [3] below. [2] The fiber manufacturing apparatus of [1] above, wherein the cross-sectional area of ​​the space surrounded by the airflow closing member in a section perpendicular to the polymer discharge direction satisfies the following formula: 1.5 ≤ A ２ / A １ ≤ 10 A １ : Cross-sectional area (mm²) at the upstream position in the polymer discharge direction ２ ) A ２ : Cross-sectional area (mm²) at the downstream position in the polymer discharge direction ２) [3] The fiber manufacturing apparatus according to [1] or [2] above, wherein the cross-sectional area in a cross-section perpendicular to the polymer discharge direction and the length in the polymer discharge direction of the space surrounded by the airflow closing member satisfy the following formula: 0.2 ≤ L / (A １ ) １／２ ≤ 5 A １ : Cross-sectional area (mm ２ ) L: Length in the polymer discharge direction (mm).

[0015] [4] The method for manufacturing fibers of the present invention that solves the above problems manufactures fibers using the fiber manufacturing apparatus according to any one of [1] to [3] above.

[0016] In the present invention, the "polymer discharge direction" refers to the direction in which the fibrous polymer is discharged from the discharge holes of the die.

[0017] In the present invention, the "swirling flow" refers to an airflow having a flow that continuously rotates in the circumferential direction around a point on a plane perpendicular to the longitudinal direction of the fiber.

[0018] In the present invention, the "polymer discharge portion" refers to a space extending downstream in the polymer discharge direction from the discharge holes of the die, having the same cross-sectional area as the area of the discharge holes, and being a cylindrical space with a length of 0.5 mm downstream in the polymer discharge direction from the discharge holes.

[0019] According to the present invention, by applying a stretching force due to the revolution of the yarn while maintaining the temperature in the stretching portion to the fibrous polymer discharged from the discharge holes of the die, fibers with a very small diameter can be stably manufactured.

[0020] Figure 1 is a schematic cross-sectional view showing one embodiment of the fiber manufacturing apparatus of the present invention. Figure 2 is a schematic cross-sectional view showing another embodiment of the fiber manufacturing apparatus of the present invention. Figure 3 is a schematic cross-sectional view showing another embodiment of the fiber manufacturing apparatus of the present invention. Figure 4 is a schematic cross-sectional view showing another embodiment of the fiber manufacturing apparatus of the present invention. Figure 5 is a schematic cross-sectional view showing another embodiment of the fiber manufacturing apparatus of the present invention. Figure 6 is a schematic cross-sectional view showing the installation configuration of the airflow nozzle in the fiber manufacturing apparatus of the present invention. Figure 7 is a schematic diagram showing the configuration of the airflow closure member in the fiber manufacturing apparatus of the present invention. Figure 8 is a schematic diagram showing the configuration of the swirling flow formation in the space of the airflow closure member in the fiber manufacturing apparatus of the present invention. Figure 9 is a schematic diagram showing an example of the configuration of the airflow closure member in the fiber manufacturing apparatus of the present invention. Figure 10 is a schematic diagram illustrating the installation angle of the airflow nozzle. Figure 11 is a schematic diagram illustrating the injection direction of the jet flow from the airflow nozzle. Figure 12 is a schematic diagram illustrating the injection direction of the jet flow from the airflow nozzle. Figure 13 is a schematic cross-sectional view showing an embodiment of a conventional fiber manufacturing apparatus. Figure 14 is a schematic cross-sectional view showing another embodiment of a conventional fiber manufacturing apparatus. Figure 15 is a schematic cross-sectional view showing another embodiment of a conventional fiber manufacturing apparatus. Figure 16 is a schematic cross-sectional view showing the dimensions of an embodiment of the fiber manufacturing apparatus of the present invention.

[0021] The following describes in detail various embodiments of the fiber manufacturing apparatus of the present invention and methods for manufacturing fibers using the apparatus, with reference to the drawings. The figures in each drawing are schematic diagrams intended to accurately convey the essential points of the present invention or the prior art, and have been simplified. The spinning apparatus of the present invention is not particularly limited to the forms shown in these drawings, and dimensional ratios and other aspects can be changed according to the embodiment. In each drawing, Figures A, B, and C shown on the right side of the drawing are cross-sectional views along the dashed lines A, B, and C in the embodiment shown on the left side of the drawing.

[0022] First, let's explain the fiber stretching phenomenon in fiber manufacturing equipment. Figure 13 is a schematic diagram of a conventional fiber manufacturing equipment 100G, commonly known as meltblown fiber. As shown in the figure, a single fiber 4 formed from polymer 3 discharged from the discharge hole 2 of the die is directly injected with a jet stream 11 from two opposing airflow nozzles 5, and an airflow is directed parallel to the polymer discharge direction on the fiber 4 to impart a stretching force 16. The polymer 3 is discharged from the discharge hole 2 in a low viscosity state, and the stretching force 16 is applied by friction between the fiber 4 formed from the polymer 3 and the airflow, causing the fiber 4 to stretch in the polymer discharge direction. At this time, increasing the speed of the jet stream 11 increases the speed difference between the yarn and the jet stream 11, increasing friction and thus increasing the stretching force. However, in reality, increasing the speed of the jet stream 11 increases yarn oscillation in the stretching section, thus suppressing the increase in stretching force. For this reason, there are limitations to promoting stretching by directing the airflow in a parallel direction.

[0023] Figure 14 is a schematic diagram of a conventional fiber manufacturing apparatus 100H of a different form. As shown in the figure, a swirling flow 12 is made to collide with the fiber 4 immediately after it is discharged from the nozzle 1, causing the fiber 4 to revolve and thereby applying centrifugal force to promote the stretching of the fiber 4. In this apparatus, since the polymer 3 is discharged into an open space and the swirling flow 12 collides with the fiber 4, the fiber 4 is cooled immediately after discharge and its viscosity increases, making the fiber 4 less prone to deformation and thus suppressing the stretching of the fiber 4.

[0024] Figure 15 is a schematic diagram of yet another form of conventional fiber manufacturing apparatus 100I. In this form, in order to suppress the cooling of the fibers 4 at the polymer discharge section and promote stretching, an airflow closure member 6I is installed around the polymer discharge section to suppress cooling. However, if the space 7 surrounded by the airflow closure member 6 is narrowed in order to suppress the cooling of the fibers 4, the swirling fibers 4 will adhere to the walls of the airflow closure member 6, and the stretching of the fibers 4 will be suppressed.

[0025] The inventors, after diligent research to solve the above problems, focused on the shape of the space enclosed by the airflow closure member 6, where centrifugal force is generated when centrifugal force is applied to the fiber 4 in order to stretch the fiber 4. When centrifugal force is applied to the fiber 4, the fiber 4 moves in a spiral trajectory that expands downstream, with the discharge hole 2 of the nozzle 1 as a fixed point. Therefore, after discharge from the nozzle 1, the area of ​​movement of the fiber 4 expands downstream. Thus, the inventors considered that by optimizing the shape of the space 7 enclosed by the airflow closure member 6, it might be possible to stretch the fiber 4 by applying centrifugal force while keeping the polymer discharge section warm.

[0026] The relationship between the configuration of the airflow closure member 6 and the stretching of the fibers 4 will now be explained. High-temperature polymer 3 is discharged from the discharge hole 2 of the nozzle 1, and then the polymer 3 cools and solidifies through heat exchange with the surrounding gas, forming fibers 4. The higher the ambient temperature of the fibers 4, the slower the cooling rate of the fibers 4 becomes, and the longer the stretching section after discharge becomes, thus promoting the stretching of the fibers 4. Here, if the airflow closure member 6 is installed around the polymer discharge section, the diffusion of the high-temperature gas sprayed from the airflow nozzle 5 into the atmosphere is suppressed, and the area near the polymer discharge section can be kept at a high temperature. Here, if the cross-sectional area of ​​the space 7 surrounded by the airflow closure member 6 in the direction perpendicular to the discharge direction of the polymer 3 is large, the atmosphere can easily enter the space 7, so the atmosphere flows into the space 7 and the temperature at the polymer discharge section tends to decrease. On the other hand, if the cross-sectional area of ​​the space 7 surrounded by the airflow closure member 6 in the direction perpendicular to the polymer 3 discharge direction is narrow, the distance between the polymer discharge section and the wall of the airflow closure member 6 becomes shorter, making it easier for the fibers 4 to adhere to the wall, thus suppressing the stretching of the fibers 4. In this way, in order to promote the stretching of the fibers 4, it is important to make the airflow closure member 6 shaped in such a way that the fibers 4 do not adhere to the wall of the airflow closure member 6, and that the inflow of air into the space 7 surrounded by the airflow closure member 6 is suppressed, thereby maintaining the temperature of the polymer discharge section. The inventors have found that by increasing the cross-sectional area of ​​the space 7 surrounded by the airflow closure member 6 in the direction perpendicular to the polymer 3 discharge direction toward the downstream side in the polymer discharge direction, the fibers 4 do not adhere to the wall of the airflow closure member 6, the temperature of the polymer discharge section can be maintained, and consequently the stretching of the fibers 4 can be promoted, resulting in thinner fibers 4. Furthermore, when spinning the fibers 4 by revolving them in the swirling flow 12, frictional force is generated on the fiber surface, causing the fibers 4 to rotate on their own. This rotation also promotes the thinning of the fibers 4 by causing them to twist. Note that if the direction of extrusion of the polymer 3 from the extrusion hole 2 is vertical, the direction perpendicular to the extrusion direction of the polymer 3 is horizontal. Therefore, in the following explanation, the direction perpendicular to the extrusion direction of the polymer 3 may be described as the horizontal direction.

[0027] The fiber manufacturing apparatus of the present invention will be described with reference to Figure 1. Figure 1 is a schematic cross-sectional view of one embodiment of a fiber manufacturing apparatus that revolves fibers 4 by a swirling flow 12. The fiber manufacturing apparatus 100 shown in Figure 1 consists of a nozzle 1 having a discharge hole 2 for discharging polymer 3, which is the raw material for the fibers 4, in a fibrous form; an airflow closure member 6 that surrounds a space 7 through which the fibers 4 pass downstream of the discharge hole 2 in the polymer discharge direction; an airflow nozzle 5 that injects an airflow 11 (hereinafter referred to as jet flow 11) into the space 7 surrounded by the airflow closure member 6; and a winding roller 14 for winding the fibers 4. The airflow closure member 6 surrounds the space 7 through which the fibers 4 pass with a wall, and the horizontal cross-sectional area of ​​the space 7 expands continuously toward the downstream side. The jet flow 11 is injected from the airflow nozzle 5 toward the inner wall surface of the airflow closure member 6, and a swirling flow 12 is formed in the space 7. Then, the fibers 4 obtained from the polymer 3 discharged from the nozzle 1 are passed through this swirling flow 12. The fibers 4 that have passed through the swirling flow 12 then exit through the lower opening 10, which is the lower opening of the airflow closing member 6, and are wound up by the winding roller 14.

[0028] Although the fibrous polymer 3 immediately after being discharged from the discharge hole 2 has not yet cooled and solidified, and therefore has not yet formed into fibers 4, in this application, this fibrous polymer 3 will also be described as fibers 4.

[0029] Referring to Figure 7, the specific configuration of the airflow closure member 6 will be explained. The airflow closure member 6 is composed of a conical wall 8, and the space 7 surrounded by the wall 8 serves as the airflow passage. The space 7 is a through hole that penetrates from one end face to the other end face of the airflow closure member 6.

[0030] The airflow through the airflow closure member 6 will be explained with reference to Figures 8 and 12. Figure 8 is a schematic diagram showing the form of swirling flow formation within the space 7 enclosed by the airflow closure member 6, and Figure 12 is a schematic diagram illustrating the injection direction of the jet stream 11 from the airflow nozzle 5. As shown in Figure 8, a high-speed swirling flow 12 is formed by injecting a jet stream 11 having a velocity component in the circumferential direction of the fiber 4 into the space 7 so as to collide with the inner wall surface of the wall 8 of the airflow closure member 6 from the airflow nozzle 5. Here, as shown in Figure 12, the injection direction of the jet stream 11 is defined as the radial direction from the tip of the airflow nozzle 5 toward the center of the fiber 4, and the circumferential direction being tilted 90° from the radial direction.

[0031] Refer to Figure 1 again. As shown in the cross-sectional view along line A, a jet stream 11 with a velocity component in the circumferential direction of the fiber 4 is injected from the airflow nozzle 5 so as to collide with the inner wall surface of the airflow closing member 6. As a result, a swirling flow 12 is formed around the fiber 4, as shown in the cross-sectional view along line B. As the fiber 4 passes through the swirling flow 12, the fiber 4 revolves at high speed. This causes centrifugal force to act on the fiber 4 at the polymer discharge section, stretching the fiber 4. This stretching method promotes the reduction of the fiber diameter, so that a stable small-diameter fiber 4 can be obtained. The revolving speed of the fiber 4 due to the swirling flow 12 is preferably 100 times / second or more, and more preferably 500 times / second or more.

[0032] In the conventional fiber manufacturing apparatus 100H shown in Figure 14, the jet stream 11 is injected from the airflow nozzle 5 into an open space that is not surrounded by walls or the like. Immediately after injection, the jet stream 11 expands and diffuses, making it difficult to form a swirling flow 12. In other words, in order to generate a swirling flow 12 that allows the fibers 4 to revolve sufficiently, it is necessary to prevent the diffusion of the jet stream 11. In the fiber manufacturing apparatus 100 of the present invention, by installing an airflow closing member 6, the diffusion of the jet stream 11 can be prevented, and the fibers 4 can be made smaller in diameter.

[0033] Refer to Figure 16. Line A indicates the upstream position of the airflow closure member 6 in the polymer discharge direction, and line B indicates the downstream position. The horizontal cross-sectional area of ​​the space 7 enclosed by the airflow closure member 6 at the position of line A (the position of the upper opening 9, which is the upper opening of the airflow closure member 6) is A. １The horizontal cross-sectional area at position B (the lower opening 10, which is the opening below the airflow closing member 6) is A ２ Let L be the length in the polymer discharge direction from line A to line B, and then describe a preferred configuration of the airflow closing member 6.

[0034] Horizontal cross-sectional area A at the position of line A in space 7 １ Horizontal cross-sectional area A at the position of line B relative to line B ２ If the expansion ratio is too large, air will easily flow into the space 7, causing the fibers 4 to cool at the polymer discharge section and making them difficult to stretch. If the expansion ratio is too small, the space will not be large enough relative to the orbital radius of the fibers 4, causing the fibers 4 to adhere to the wall surface of the airflow closure member 6 when passing through, which will easily worsen their stretchability and spinnability. Therefore, the cross-sectional area A １ Cross-sectional area A ２ A is the magnification ratio. ２ / A １ Preferably, the ratio is between 1.5 and 10 times, and more preferably between 2 and 5 times.

[0035] Horizontal cross-sectional area A at the position of line A in space 7 １ If the cross-sectional area A is too wide, air can easily flow into the space 7, causing the fibers 4 to cool at the polymer discharge section and making them difficult to stretch. １ If the cross-sectional area A is too narrow, the fibers 4 will adhere to the wall surface of the airflow closure member 6 when they pass through, which can easily worsen their stretchability and spinnability. １ 0.5 mm ２ 50mm or more ２ The following is preferable: 3 mm ２ 30mm or more ２ The following are even more preferable.

[0036] Horizontal cross-sectional area A at the position of line A in space 7 １ If the length L of the polymer discharge direction of space 7 is too short, air will easily flow into space 7, making it difficult to achieve the heat retention effect. Cross-sectional area A １ If the length L is too long, the fibers 4 tend to adhere to the wall surface of the airflow closure member 6 when they pass through, which can worsen the stretchability and spinnability. Therefore, the cross-sectional area A １The length L relative to the square root is preferably 0.2 times or more and 5 times or less, and more preferably 0.5 times or more and 3 times or less.

[0037] The center of the swirling flow 12 formed by the airflow closure member 6 lies on the axis extending from the discharge hole 2 in the direction of polymer 3 discharge, allowing the fibers 4 to revolve efficiently. Therefore, it is preferable that the central axis of the spiral of the swirling flow 12 coincides with the axis extending from the discharge hole 2 in the direction of polymer 3 discharge.

[0038] In order to form a swirling flow 12 in the space 7 surrounded by the airflow closing member 6, the horizontal cross-sectional area A of the space 7 １ It is preferable that the minimum cross-sectional area of ​​the airflow nozzle 5 is smaller. The cross-sectional shape of the airflow nozzle 5 is not limited to circular or rectangular; it can be any cross-sectional shape.

[0039] Figure 2 is a schematic cross-sectional view of a fiber manufacturing apparatus 100A equipped with an airflow closure member 6A of a different form from the airflow closure member 6 of the fiber manufacturing apparatus 100 in Figure 1. In the airflow closure member 6 of the fiber manufacturing apparatus 100, the horizontal cross-sectional area of ​​the inner space 7 continuously increases toward the downstream side in the polymer discharge direction, whereas in the airflow closure member 6A of the fiber manufacturing apparatus 100A, the horizontal cross-sectional area of ​​the inner space 7 increases stepwise toward the downstream side in the polymer discharge direction. Even with a form like the airflow closure member 6A, the same effect as the airflow closure member 6 can be achieved. Also, the horizontal cross-sectional area A at the position of the upper opening 9 of the space 7 is the same for the airflow closure member 6A as for the airflow closure member 6. １ Horizontal cross-sectional area A at the position of the lower opening 10 of space 7 ２ A is the magnification ratio. ２ / A １ The cross-sectional area A is preferably 1.5 times or more and 10 times or less, and more preferably 2 times or more and 5 times or less. １ 0.5 mm ２ 50mm or more ２ The following is preferable: 3 mm ２ 30mm or more ２ The following are even more preferable.

[0040] Furthermore, the airflow closure member 6 in the present invention can take various forms. Figure 9 is a schematic diagram showing examples of forms of the airflow closure member 6. Figure 9(a) shows an airflow closure member 6J in which the horizontal cross-section of the inner space 7 is circular and has a tapered shape that expands continuously. Figure 9(b) shows an airflow closure member 6K in which the horizontal cross-section of the inner space 7 is circular and has a stepped shape that expands in stages. Figure 9(c) shows an airflow closure member 6L in which the horizontal cross-section of the inner space 7 is circular and combines a straight shape with a continuously expanding taper. Figure 9(d) shows an airflow closure member 6M in which the horizontal cross-section of the inner space 7 is rectangular and expands. Figure 9(e) shows an airflow closure member 6N in which the horizontal cross-section of the inner space 7 is circular and has a passage formed in the wall. In all of the airflow closure members shown in Figures 9(a) to (e), the cross-sectional area of ​​the inner space 7 perpendicular to the polymer 3 discharge direction increases continuously or in stages toward the downstream side in the polymer discharge direction, so the same effect as the airflow closure member 6 in Figure 1 and the airflow closure member 6A in Figure 2 can be achieved. Also, in all of the airflow closure members shown in Figures 9(a) to (e), the cross-sectional area A is the same as that of the airflow closure member 6 in Figure 1 and the airflow closure member 6A in Figure 2. １ Cross-sectional area A ２ A is the magnification ratio. ２ / A １ The cross-sectional area A is preferably 1.5 times or more and 10 times or less, and more preferably 2 times or more and 5 times or less. １ 0.5 mm ２ 50mm or more ２ The following is preferable: 3 mm ２ 30mm or more ２ The following is even more preferable. The form of the airflow closing member 6 may be other than those shown in Figures 9(a) to (e).

[0041] Figure 10 is a schematic diagram illustrating the installation angle of the airflow nozzle 5. If the angle α between the discharge direction of polymer 3 and the injection direction of the jet 11 from the airflow nozzle 5 is small, the rotational speed component of the swirling flow 12 tends to weaken. Conversely, if the angle α is greater than 90°, the airflow is injected in the opposite direction to the discharge direction of polymer 3, so an airflow opposite to the stretching direction of the fiber 4 is generated at the polymer discharge section, and the stretching of the fiber 4 tends to be hindered. For this reason, an angle α of 5° or more and 90° or less is preferable.

[0042] Figure 11 is a schematic diagram illustrating the installation angle of the airflow nozzle 5 in a cross-section perpendicular to the direction of travel of the fiber 4. If the angle β between the straight line connecting the center of the discharge part of the airflow nozzle 5 and the center of the fiber 4 (the shortest straight line connecting the airflow nozzle 5 and the fiber 4) and the injection direction of the jet 11 is small, the jet 11 will directly collide with the fiber 4, making it difficult to form a swirling flow 12. Conversely, if the angle β is large, the jet will be injected in the opposite direction to the fiber 4, making it easy for energy loss to occur. For this reason, an angle β of 5° to 90° is preferable.

[0043] Figure 3 is a schematic cross-sectional view showing another embodiment of the fiber manufacturing apparatus of the present invention. In the fiber manufacturing apparatus 100 of Figure 1, a jet stream 11 is supplied by a single airflow nozzle 5, and a swirling flow 12 is formed inside the airflow closure member 6. As shown in the fiber manufacturing apparatus 100B of Figure 3, by installing multiple airflow nozzles 5, the jet stream 11 can be supplied in a dispersed manner, and the swirling flow 12 can be formed more stably. Therefore, it is preferable that there be two or more airflow nozzles 5 supplying the jet stream 11, and more preferably three or more.

[0044] When using two or more airflow nozzles 5, a smooth swirling flow 12 can be formed by supplying the jet stream 11 evenly, allowing the fibers 4 to rotate continuously. Therefore, when using two or more airflow nozzles 5, it is preferable to evenly arrange the airflow nozzles 5 on the circle shown by the dotted line in Figure 3A and inject the jet stream 11 in the circumferential direction of this circle.

[0045] Figure 4 is a schematic cross-sectional view showing another embodiment of the fiber manufacturing apparatus of the present invention. In the fiber manufacturing apparatus 100B of Figure 3, the jet stream 11 is injected downstream of the polymer discharge surface of the nozzle 1, whereas in this fiber manufacturing apparatus 100C, the airflow closure member 6C extends upstream of the polymer discharge surface, and the jet stream 11 is injected upstream of the polymer discharge surface. By injecting the jet stream 11 upstream of the polymer discharge surface, a swirling flow 12 can be formed in advance, and this swirling flow 12 can be injected onto the fibers 4 discharged from the discharge hole 2. In this way, the swirling flow 12 can be more stably brought into contact with the fibers 4, so the orbital motion of the fibers 4 is stabilized, and fibers 4 with less diameter variation can be obtained.

[0046] Figure 6 is a schematic cross-sectional view showing another embodiment of the fiber manufacturing apparatus of the present invention. Note that the winding roller 14 is not shown in Figure 6. In the fiber manufacturing apparatus 100 of Figure 1, the supply of the swirling flow 12 may become unstable due to the influence of gases other than the jet flow 11 at the upper opening 9 of the airflow closure member 6. Therefore, as shown in the fiber manufacturing apparatuses 100E and 100F of Figure 6, the upper opening 9 of the airflow closure member 6 may be blocked except for the jet opening of the airflow nozzle 5.

[0047] Next, a common preferred embodiment of the present invention will be described. Refer to Figures 1 and 5. The method for recovering the fibers 4 is not limited to the winding roller 14 shown in Figure 1, but may also be recovered using a fiber drum or a conveyor 15 shown in Figure 5. By using a conveyor 15 or a fiber drum, the fibers 4 can be moved without restricting their position at the recovery location, allowing them to revolve freely without being constrained in position, thereby enhancing the stretching effect.

[0048] The present invention is highly versatile and can be applied to the manufacture of all known fibers. Therefore, it is not particularly limited by the polymer constituting the fiber. For example, examples of polymers constituting the fiber include polyester, polyamide, polyphenylene sulfide, polyolefin, polyethylene, polypropylene, and so on. Furthermore, the above-mentioned polymers may contain additives such as titanium dioxide as a matting agent, silicon dioxide, kaolin, color inhibitors, stabilizers, antioxidants, deodorants, flame retardants, yarn friction reducers, coloring pigments, surface modifiers, and various functional particles and organic compounds, as long as they do not impair spinning stability, etc. Copolymerization may also be included.

[0049] The polymer that makes up the fiber may consist of a single component or multiple components. In the case of multiple components, examples of configurations include core-sheath and side-by-side structures.

[0050] The cross-sectional shape of the fiber may be irregular, such as round, triangular, flat, polygonal, or star-shaped, or it may be hollow. In this case, the surface area per unit volume increases when the cross-sectional shape differs from a perfect circle, making it easier to be subjected to swirling flow and increasing the orbital speed, thereby enabling the production of thinner fibers. Therefore, a cross-sectional shape that is flattened from a perfect circle is preferred, and a cross-sectional shape with irregularities on the surface is more preferred.

[0051] Furthermore, while the present invention aims to produce fine-diameter fibers, the single-fiber fineness is not particularly limited.

[0052] The present invention will be described in more detail below with reference to examples. The methods for measuring characteristic values ​​in the examples are as follows: (1) Average fiber diameter (μm) Twenty samples were randomly taken from the spun fibers, and surface photographs were taken at 1000x magnification with a microscope. The width of the fibers was measured from the sample photographs, and the average value was taken as the average fiber diameter. (2) Temperature of the polymer discharge section (°C) A thermocouple measuring unit was placed at the outlet of the nozzle discharge hole, and hot air was supplied to the airflow nozzle to measure the ambient temperature of the polymer discharge section of the nozzle. This measurement was repeated three times to obtain the polymer discharge section temperature (°C). (3) Adhesion of fibers to the wall surface A high-speed video camera was used to photograph the downstream position of the space 7 surrounded by the airflow closure member 6 for 1 second from downstream of the airflow closure member, and it was measured whether the fibers 4 adhered to the inner wall surface of the airflow closure member 6. The adhesion of the fibers 4 to the inner wall surface of the airflow closing member 6 was determined as "A" if it occurred two times or less, "B" if it occurred three to five times, and "C" if it occurred six or more times.

[0053] [Example 1] Fibers 4 were spun using the fiber manufacturing apparatus 100 shown in Figure 1. The die 1 has one discharge hole 2 with a hole diameter of 0.25 mm. There is one airflow nozzle 5 with a hole diameter of 2 mm. The airflow nozzle 5 was installed such that the angle α between the direction of the jet stream 11 ejected from the airflow nozzle 5 and the direction of travel of the fiber 4 is 10°, and the angle β between the line connecting the center of the discharge part of the airflow nozzle 5 and the center of the fiber 4 and the direction of the jet stream 11 ejected is 80°. The airflow closure member 6 has a horizontal cross-sectional area A of the space 7 at the uppermost opening 9 at the uppermost position in the polymer discharge direction. １ 20mm ２ , the horizontal cross-sectional area A of the space 7 at the position of the lowest lower opening 10 ２ 25mm ２ The length L from the upstream to the downstream position in the polymer discharge direction of space 7 is 1 mm, and the horizontal cross-sectional area of ​​space 7 increases continuously toward the downstream side in the polymer discharge direction.

[0054] The raw material resin conforms to ASTM-D1238, with a weight of 2.16 kg, a melt flow rate of 1100 g / 10 min at 230°C, and a density of 0.9 g / cm³. ３Polypropylene resin with a melting point of 180°C was used. Polymer 3, with a molten resin temperature of 280°C, was discharged from the discharge hole 2 of the nozzle 1 at a single-hole discharge rate of 2 g / min. Hot air at 280°C was injected from the airflow nozzle 5 into the space 7 of the airflow closing member 6, and the fibers 4 were stretched while centrifugal force was applied by the swirling flow 12 from a position directly below the discharge hole 2. The stretched fibers 4 were wound up by the winding roller 14.

[0055] The polymer discharge temperature during spinning was 250°C, the adhesion of fibers 4 to the inner wall of the airflow closure member 6 was "A", and the average fiber diameter of the collected fibers 4 was 2.7 μm.

[0056] [Example 2] Fibers 4 were spun using the fiber manufacturing apparatus 100A shown in Figure 2. The airflow closing member 6A has a horizontal cross-sectional area A at the position of the upper opening 9 of the space 7. １ 20mm ２ , horizontal cross-sectional area A at the position of the lower opening 10 ２ 25mm ２ The length L of the space 7 is 1 mm, and the horizontal cross-sectional area of ​​the space 7 increases gradually toward the downstream side in the polymer discharge direction. The rest of the apparatus configuration is the same as in Example 1. Fibers 4 were spun under the same conditions as in Example 1. The temperature of the polymer discharge section during spinning was 248°C, the adhesion of fibers 4 to the inner wall surface of the airflow closure member 6 was "A", and the average fiber diameter of the collected fibers 4 was 2.7 μm.

[0057] [Example 3] Fibers 4 were spun using the fiber manufacturing apparatus 100 shown in Figure 1. The airflow closure member 6 has a horizontal cross-sectional area A at the position of the upper opening 9 of the space 7. １ 20mm ２ , horizontal cross-sectional area A at the position of the lower opening 10 ２ 40mm ２ The length L of the space 7 is 5 mm, and the horizontal cross-sectional area of ​​the space 7 increases continuously toward the downstream side in the polymer discharge direction. The rest of the apparatus configuration is the same as in Example 1. Fibers 4 were spun under the same conditions as in Example 1. The temperature of the polymer discharge section during spinning was 262°C, the adhesion of fibers 4 to the inner wall surface of the airflow closure member 6 was "A", and the average fiber diameter of the collected fibers 4 was 2.2 μm.

[0058] [Example 4] Fibers 4 were spun using the fiber manufacturing apparatus 100D shown in Figure 5. A conveyor 15 was provided instead of a winding roller 14. The rest of the apparatus configuration was the same as in Example 3. Fibers 4 were stretched under the same conditions as in Example 3, and instead of winding the stretched fibers 4 with the winding roller 14, they were collected as a sheet using the conveyor 15. The temperature of the polymer discharge section during spinning was 262°C, the adhesion of fibers 4 to the inner wall surface of the airflow closure member 6 was "A", and the average fiber diameter of the collected fibers 4 was 2.2 μm.

[0059] [Example 5] Fibers 4 were spun using the fiber manufacturing apparatus 100 shown in Figure 1. The airflow closure member 6 has a horizontal cross-sectional area A at the position of the upper opening 9 of the space 7. １ 20mm ２ , horizontal cross-sectional area A at the position of the lower opening 10 ２ 160mm ２ The length L of the space 7 is 5 mm, and the horizontal cross-sectional area of ​​the space 7 increases continuously toward the downstream side in the polymer discharge direction. The rest of the apparatus configuration is the same as in Example 1. Fibers 4 were spun under the same conditions as in Example 1. The temperature of the polymer discharge section during spinning was 260°C, the adhesion of fibers 4 to the inner wall surface of the airflow closure member 6 was "A", and the average fiber diameter of the collected fibers 4 was 3.0 μm.

[0060] [Example 6] Fibers 4 were spun using the fiber manufacturing apparatus 100 shown in Figure 1. The airflow closure member 6 has a horizontal cross-sectional area A at the position of the upper opening 9 of the space 7. １ 20mm ２ , horizontal cross-sectional area A at the position of the lower opening 10 ２ 240mm ２ The length L of the space 7 is 5 mm, and the horizontal cross-sectional area of ​​the space 7 increases continuously toward the downstream side in the polymer discharge direction. The rest of the apparatus configuration is the same as in Example 1. Fibers 4 were spun under the same conditions as in Example 1. The temperature of the polymer discharge section during spinning was 260°C, the adhesion of fibers 4 to the inner wall surface of the airflow closure member 6 was "A", and the average fiber diameter of the collected fibers 4 was 3.3 μm.

[0061] [Example 7] Fibers 4 were spun using the fiber manufacturing apparatus 100 shown in Figure 1. The airflow closure member 6 has a horizontal cross-sectional area A at the position of the upper opening 9 of the space 7. １ 20mm ２ , horizontal cross-sectional area A at the position of the lower opening 10 ２ 40mm ２ The length L of the space 7 is 1 mm, and the horizontal cross-sectional area of ​​the space 7 increases continuously toward the downstream side in the polymer discharge direction. The rest of the apparatus configuration is the same as in Example 1. Fibers 4 were spun under the same conditions as in Example 1. The temperature of the polymer discharge section during spinning was 262°C, the adhesion of fibers 4 to the inner wall surface of the airflow closure member 6 was "A", and the average fiber diameter of the collected fibers 4 was 3.0 μm.

[0062] [Example 8] Fibers 4 were spun using the fiber manufacturing apparatus 100 shown in Figure 1. The airflow closure member 6 has a horizontal cross-sectional area A at the position of the upper opening 9 of the space 7. １ 20mm ２ , horizontal cross-sectional area A at the position of the lower opening 10 ２ 40mm ２ The length L of the space 7 is 0.5 mm, and the horizontal cross-sectional area of ​​the space 7 increases continuously toward the downstream side in the polymer discharge direction. The rest of the apparatus configuration is the same as in Example 1. Fibers 4 were spun under the same conditions as in Example 1. The temperature of the polymer discharge section during spinning was 262°C, the adhesion of fibers 4 to the inner wall surface of the airflow closure member 6 was "A", and the average fiber diameter of the collected fibers 4 was 3.8 μm.

[0063] [Example 9] Fibers 4 were spun using the fiber manufacturing apparatus 100 shown in Figure 1. The airflow closure member 6 has a horizontal cross-sectional area A at the position of the upper opening 9 of the space 7. １ 5mm ２ , horizontal cross-sectional area A at the position of the lower opening 10 ２ 20mm ２The length L of the space 7 is 5 mm, and the horizontal cross-sectional area of ​​the space 7 increases continuously toward the downstream side in the polymer discharge direction. The rest of the apparatus configuration is the same as in Example 1. Fibers 4 were spun under the same conditions as in Example 1. The temperature of the polymer discharge section during spinning was 258°C, the adhesion of fibers 4 to the inner wall surface of the airflow closure member 6 was "A", and the average fiber diameter of the collected fibers 4 was 2.1 μm.

[0064] [Example 10] Fibers 4 were spun using the fiber manufacturing apparatus 100 shown in Figure 1. The airflow closure member 6 has a horizontal cross-sectional area A at the position of the upper opening 9 of the space 7. １ 5mm ２ , horizontal cross-sectional area A at the position of the lower opening 10 ２ 20mm ２ The length L of the space 7 is 10 mm, and the horizontal cross-sectional area of ​​the space 7 increases continuously toward the downstream side in the polymer discharge direction. The rest of the apparatus configuration is the same as in Example 1. Fibers 4 were spun under the same conditions as in Example 1. The temperature of the polymer discharge section during spinning was 257°C, the adhesion of fibers 4 to the inner wall surface of the airflow closure member 6 was "B", and the average fiber diameter of the collected fibers 4 was 2.1 μm.

[0065] [Comparative Example 1] Fibers 4 were spun using the fiber manufacturing apparatus 100H shown in Figure 14. The apparatus configuration was the same as in Example 1, except that it did not have an airflow closure member 6. Fibers 4 were spun under the same conditions as in Example 1. The temperature of the polymer discharge section during spinning was 190°C, and the average fiber diameter of the collected fibers 4 was 4.1 μm.

[0066] [Comparative Example 2] Fibers 4 were spun using the fiber manufacturing apparatus 100I shown in Figure 15. The airflow closure member 6 has a cross-sectional area of ​​space 7 of 20 mm². ２ The temperature is constant, and the length L of the space 7 is 5 mm. The rest of the apparatus configuration is the same as in Example 1. Fibers 4 were spun under the same conditions as in Example 1. The temperature of the polymer discharge section during spinning was 262°C, the adhesion of fibers 4 to the inner wall surface of the airflow closure member 6I was "C", and the average fiber diameter of the collected fibers was 2.2 μm.

[0067] Tables 1 and 2 summarize the spinning conditions and results for each example and comparative example.

[0068]

[0069]

[0070] In any of Examples 1 to 9, the fibers 4 hardly adhered to the inner wall surface of the airflow closing member 6, and the fibers 4 with a small diameter could be collected. In Example 1, the space 7 surrounded by the airflow closing member 6 continuously expanded in the downstream direction. In Example 2, the space surrounded by the airflow closing member 6A expanded stepwise in the downstream direction. However, the fibers 4 with the same average fiber diameter could be collected in both cases. In Example 3, since the shape of the airflow closing member 6 was optimized more than that in Example 1, the temperature of the polymer discharge portion could be kept higher than that in Example 1, and the thinning of the fibers 4 was promoted.

[0071] In Example 4, the fibers 4 were collected by a conveyor, but the fibers 4 with an average fiber diameter equivalent to that in Example 3 collected by a roller could be collected. In Example 5, the expansion ratio A １ of the cross-sectional area A ２ with respect to the cross-sectional area A ２ of the airflow closing member 6 was large, and the effect of thinning the fibers 4 decreased. In Example 6, the expansion ratio A １ / A １ of the cross-sectional area A ２ with respect to the cross-sectional area A ２ of the airflow closing member 6 was even larger, and the effect of thinning the fibers 4 further decreased. In Example 7, the length L with respect to the square root of the cross-sectional area A １ of the airflow closing member 6 was smaller than that in Example 3, and the effect of thinning the fibers 4 decreased. In Example 8, the length L with respect to the square root of the cross-sectional area A １ of the airflow closing member 6 was even smaller than that in Example 7, and the effect of thinning the fibers 4 further decreased. In Example 9, it is one of the preferable shapes of the airflow closing member 6. Similar to Example 3, there was no adhesion of the polymer to the inner wall surface of the airflow closing member 6, and by keeping the temperature of the polymer discharge portion high, the thinning of the fibers 4 was promoted. In Example 10, the length L with respect to the square root of the cross-sectional area A １ of the airflow closing member 6 was larger than that in Example 9, and the adhesion of the fibers 4 increased. １ of the airflow closing member 6 was larger than that in Example 9, and the adhesion of the fibers 4 increased.

[0072] Comparative Example 1 lacked an airflow closure member 6, and therefore could not properly form a swirling flow 12, resulting in the inability to reduce the diameter of the fibers 4. Comparative Example 2, having an airflow closure member 6, was able to form a swirling flow and reduce the diameter of the fibers 4. However, because the cross-sectional area of ​​the space 7 surrounded by the airflow closure member 6 in the direction perpendicular to the discharge direction of the polymer 3 was constant, the fibers 4 frequently adhered to the wall surface of the airflow closure member 6.

[0073] The manufacturing method and apparatus of the present invention can be applied not only to filaments but also to the spinning of fibers for other uses, such as nonwoven fabrics.

[0074] 1. Nozzle 2. Discharge hole 3. Polymer 4. Fiber 5. Airflow nozzle 6, 6A, 6C, 6E, 6F, 6J-6N, 6I Airflow closure member 7. Space 8. Wall 9. Upper opening 10. Lower opening 11. Jet flow 12. Swirling flow 14. Winding roller 15. Conveyor 16. Stretching force 100, 100A, 100B, 100C, 100D, 100E, 100F, 100G, 100H, 100I Fiber manufacturing equipment

Claims

1. An apparatus for producing fibers by stretching a fibrous polymer, comprising: a nozzle having a discharge hole for discharging the fibrous polymer; an airflow closure member surrounding a space through which the fibrous polymer passes, downstream of the discharge hole in the polymer discharge direction; and an airflow nozzle for injecting airflow into the space surrounded by the airflow closure member, wherein the cross-sectional area of ​​the space surrounded by the airflow closure member in a cross section perpendicular to the polymer discharge direction increases continuously or stepwise toward the downstream side in the polymer discharge direction, and the jet flow injected from the airflow nozzle into the space surrounded by the airflow closure member forms a swirling flow in the space toward the downstream side in the polymer discharge direction, causing the fibrous polymer to rotate in the swirling flow around a straight line extending from the center of the discharge hole in the polymer discharge direction.

2. The fiber manufacturing apparatus according to claim 1, wherein the cross-sectional area of ​​the space surrounded by the airflow closing member in a section perpendicular to the polymer discharge direction satisfies the following formula: 1.5 ≤ A ２ / A １ ≤ 10 A １ : Cross-sectional area (mm²) at the upstream position in the polymer discharge direction ２ ) A ２ : Cross-sectional area (mm²) at the downstream position in the polymer discharge direction ２ ) 3. The fiber manufacturing apparatus according to claim 1, wherein the cross-sectional area in a cross-section perpendicular to the polymer discharge direction and the length in the polymer discharge direction of the space surrounded by the airflow closing member satisfy the following formula: 0.2 ≦ L / (A １ ) １／２ ≦ 5 A １ : Cross-sectional area at the most upstream position in the polymer discharge direction (mm ２ ). L: Length in the polymer discharge direction (mm) 4. The fiber manufacturing apparatus according to claim 1, wherein the cross-sectional area of ​​the space surrounded by the airflow closing member in a section perpendicular to the polymer discharge direction and the length in the polymer discharge direction satisfy the following formula: 1.5 ≤ A ２ / A １ ≦10 0.2≦L / (A １ ) １／２ ≤ 5 A １ : Cross-sectional area (mm²) at the upstream position in the polymer discharge direction ２ ) A ２ : Cross-sectional area (mm²) at the downstream position in the polymer discharge direction ２ ) L: Length in the polymer discharge direction (mm) 5. A method for manufacturing fibers, comprising manufacturing fibers using a fiber manufacturing apparatus according to any one of claims 1 to 4.

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