Apparatus for producing nonwoven fabric and method for producing nonwoven fabric

Abstract

To provide an apparatus for producing a nonwoven fabric that improves the uniformity of basis weight across the width of the nonwoven fabric in a method for depositing and collecting short fibers dispersed in the air after drawing, such as in the meltblown method.SOLUTION: A production apparatus comprises a nozzle for discharging fiberized polymer and a collection section for the fiberized polymer. The nozzle includes: multiple polymer discharge holes arranged in a single row in the width direction of the nozzle; a first air current discharge section that discharges air current to impinge the discharged polymer to stretch it to form fibers; and a pair of second air current discharge sections that discharge air current to stretch the discharged polymer by impinging on it as if the discharged polymer were being virtually discharged from regions where polymer is not discharged extending in the nozzle width direction from both ends of the polymer discharge holes arranged in a single row. When the lengths in the nozzle width direction of each of the second air current discharge sections are denoted as W1 and W2, and the pitch of the polymer discharge holes arranged in a single row is denoted as P, the following equations: W1≥10×P and W2≥10×P are satisfied.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a nonwoven fabric manufacturing apparatus and a manufacturing method using the nonwoven fabric manufacturing apparatus. [Background technology]

[0002] Nonwoven fabrics are manufactured using a wide variety of methods, including dry, wet, spunbond, and meltblown processes. Even within the same process, manufacturing methods vary depending on the raw materials used and the desired quality. The meltblown process, in particular, stretches polymers using high-velocity air, allowing for the production of nonwoven fabrics with finer fibers (approximately 1 μm in diameter) than other manufacturing methods. This allows for a wide variety of applications, including hygiene materials, air filters, soundproofing materials, and secondary battery separators. In the meltblown process, the fibers are typically stretched using high-velocity air, dispersed into the air, and then shortened into short fibers, which are then collected and wound into a strip-like sheet. Therefore, controlling the airflow from the time the fibers are dispersed to the time they are collected is crucial to achieving the desired basis weight, thickness, and strength.

[0003] As an air flow control technology, a nonwoven fabric manufacturing device has been proposed that aims to improve the strength and uniformity of nonwoven fabrics when stretched. This device includes a sub-nozzle that ejects only air in the conveying direction of the collected nonwoven fabric and in the opposite direction, separate from the high-speed air ejection section attached to the main nozzle that ejects the polymer, which stretches the polymer (see Patent Document 1). High-speed air, accompanied by an accompanying airflow, disrupts the diffusion space, causing many localized entanglements in the polymer, which reduces the uniformity of the nonwoven fabric. Therefore, by ejecting air from the sub-nozzle, the inflow of the accompanying airflow into the polymer diffusion space is suppressed, improving the uniformity of the nonwoven fabric.

[0004] Furthermore, a nonwoven fabric manufacturing device has been proposed in which a pair of comb-like blades are provided on either the upstream or downstream side of the conveying direction, with the blades arranged alternately so that the gaps extending in the polymer discharge direction do not overlap when viewed from the conveying direction (see Patent Document 2). This pair of blades is inclined at different angles relative to the vertical, facing the same direction, either upstream or downstream, in the conveying direction. This pair of blades functions as a contact plate, guiding the airflow and fibers along the blades by a viscous effect known as the Coanda effect, thereby controlling the dispersion state of the polymer in the width direction as well as the conveying direction of the nonwoven fabric. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2022-010113 [Patent Document 2] Patent Publication No. 2021-123806 Summary of the Invention [Problem to be solved by the invention]

[0006] However, the technology of Patent Document 1 aims to control the conveyance direction, as sub-nozzles that eject air are installed upstream and downstream in the conveyance direction relative to the nozzle that ejects the polymer, and does not anticipate controlling the flow in the width direction, which is wider than the conveyance direction.

[0007] Furthermore, the technology of Patent Document 2 has the drawback that air flowing in from outside the device may cause turbulence in the air stretching the polymer, and that the polymer is dispersed by colliding long fibers formed by stretching the polymer, in addition to the comb-like blades, with the collection surface, and therefore, when dealing with short fibers, each of which is extremely lightweight, the dispersion effect of collisions with the collection surface cannot be fully achieved.

[0008] Furthermore, while both Patent Documents 1 and 2 describe the spunbond method as a preferred embodiment, there is a concern that the polymer may fly out of the device when using a method such as meltblowing, in which a stretched polymer is dispersed in the air.

[0009] In conventional nonwoven fabric manufacturing equipment, when polymer and air are discharged from the nozzle and collected, the flow velocity of the air toward the collection section attenuates from the widthwise edges of the nonwoven fabric due to frictional resistance with the air or wall if there is air or a wall nearby. As a result, the flow velocity increases in the widthwise center of the nonwoven fabric, and the mass density of the polymer flowing toward the collection section per unit time increases at the center. Meanwhile, the attenuation of the air flow velocity at the edges reduces the mass density of the polymer, making it easier for fiberized short fibers to scatter to the surrounding area. As a result, the collected nonwoven fabric has a high basis weight and thickness in the widthwise center, while the widthwise edges have a lower basis weight than the center. Furthermore, depending on the polymer, it may be necessary to increase the distance from the nozzle to the collection section. In this case, the flow velocity at the widthwise edges further decreases, resulting in significant differences in basis weight and thickness between the center and edges. Thus, conventional nonwoven fabric manufacturing equipment produces nonwoven fabrics with reduced basis weight and thickness uniformity, resulting in impaired strength, filtration performance, and other properties.

[0010] Therefore, the present invention provides a nonwoven fabric manufacturing device that, in a method for depositing and collecting short fibers that have dispersed in the air after drawing, such as in a melt-blowing method, prevents turbulence in the transport flow by suppressing the inflow of air from the outside, thereby ensuring controllability, and reduces the difference in the widthwise flow speed of the air flowing from the spinneret to the collection section, thereby improving the uniformity of the basis weight of the nonwoven fabric in the width direction. [Means for solving the problem]

[0011] [1] The nonwoven fabric manufacturing apparatus of the present invention, which solves the above-mentioned problems, is an apparatus for manufacturing nonwoven fabric, which is provided with a nozzle for discharging a fiberized polymer and a collecting section for collecting the fiberized polymer, The above-mentioned base is a plurality of polymer discharge holes arranged in a row in the width direction of the nozzle; a first air ejection section that ejects air onto the polymer ejected from the polymer ejection hole to stretch the polymer and turn it into fiber; a pair of second air ejection sections which are regions in which no polymer is ejected and which extend in the width direction of the nozzle from both ends of the polymer ejection holes arranged in a row, and which eject air so as to hit the virtually ejected polymer and stretch the virtually ejected polymer, assuming that a polymer is virtually ejected from each of the regions, When the lengths of the second air ejection portions in the nozzle width direction are W1 and W2, and the pitch of the polymer ejection holes arranged in a row is P, W1≧10×P and W2≧10×P are satisfied.

[0012] The nonwoven fabric manufacturing apparatus of the present invention preferably has any one of the following forms [2] to [5]. [2] The nonwoven fabric manufacturing apparatus according to [1] above, wherein W is the length of the first air ejection section, and W1≦0.5W and W2≦0.5W are satisfied. [3] The nonwoven fabric manufacturing apparatus according to [1] or [2] above, further comprising a partition wall surrounding the polymer path from the spinneret to the collecting section. [4] The nonwoven fabric manufacturing apparatus according to [3], wherein the distance between the two partition walls facing each other in the width direction of the nozzle is L1, and the distance in the width direction of the nozzle from the end of the second air discharge portion to the partition wall is L2, satisfying L2 / L1 ≧ 0.05. [5] The nonwoven fabric manufacturing apparatus according to any one of [1] to [4] above, wherein the first polymer discharge section and the second polymer discharge section are on the same straight line when viewed from the polymer discharge direction, and the first polymer discharge section and the second polymer discharge section are on the same straight line when viewed from a direction perpendicular to the polymer discharge direction and the nozzle width direction. [6] The nonwoven fabric manufacturing apparatus according to any one of [1] to [5] above, wherein the die can be divided into a member having the first air ejection section, one member having the second air ejection section, and the other member having the second air ejection section.

[0013] [7] The method for producing a nonwoven fabric of the present invention uses the nonwoven fabric production apparatus described above in [6], and makes the flow rate of the air discharged from the first air discharge section and the flow rate of the air discharged from the second air discharge section the same. [Effects of the Invention]

[0014] According to the nonwoven fabric manufacturing apparatus of the present invention, the air flow within the apparatus can be controlled while suppressing scattering of fibers formed by stretching the polymer discharged from the nozzle outside the apparatus, thereby making it possible to manufacture nonwoven fabric with excellent uniformity of basis weight in the width direction. [Brief explanation of the drawings]

[0015] [Figure 1] 1 is a schematic diagram of a first embodiment of a nonwoven fabric manufacturing apparatus of the present invention, including a longitudinal cross-sectional view as seen from the MD direction and a cross-sectional view along the arrows AA and BB. [Figure 2] 2 is a schematic diagram of a second embodiment of the nonwoven fabric manufacturing apparatus of the present invention, including a longitudinal cross-sectional view as seen from the MD direction and a cross-sectional view along the arrows AA and BB. FIG. [Figure 3] 2 is a schematic diagram of a comparative example of the present invention, including a longitudinal cross-sectional view as seen from the MD direction and a cross-sectional view as seen from the AA arrows. FIG. [Figure 4] This is a longitudinal cross-sectional view seen from the MD direction, showing the flow velocity evaluation position in fluid analysis. [Figure 5] This is a longitudinal cross-sectional view seen from the MD direction, showing the flow velocity in fluid analysis. [Figure 6] This is the same fluid analysis result as in Figure 5, but the display format is different from Figure 5. DETAILED DESCRIPTION OF THE INVENTION

[0016] Hereinafter, embodiments of the present invention will be described with reference to Figures 1 and 2. However, the present invention is not limited to these. In the following description, the MD (machine direction) refers to the direction in which the nonwoven fabric is conveyed, and the TD (transverse direction) refers to the width direction of the nonwoven fabric.

[0017] [First embodiment] Please refer to Figure 1. Figure 1 is a schematic diagram of a first embodiment of a nonwoven fabric manufacturing apparatus of the present invention. The left side of the page is a longitudinal cross-sectional view seen from the MD direction. The right side of the page is a cross-sectional view taken along the lines AA and BB of the left side of the page. The nonwoven fabric manufacturing apparatus 1 comprises a spinneret 2, a collection section 3 that accumulates and collects the stretched polymer, and a partition wall 11. The partition wall 11 surrounds a diffusion space 4 through which the polymer diffuses from the spinneret 2 toward the collection section 3.

[0018] The spinneret 2 includes a plurality of polymer discharge holes 5 arranged in a row in the TD direction through which the polymer, a raw material for the nonwoven fabric, is discharged, a first air discharge section 6 having a length W through which air is discharged, and a pair of second air discharge sections 7, 7' having lengths W1 and W2 through which air is discharged to areas other than the first air discharge section 6. The air discharged from the first air discharge section 6 hits the polymer discharged from the polymer discharge holes 5, stretching the polymer to form fibers. The air discharged from the second air discharge sections 7, 7' is discharged so as to hit the virtually discharged polymer and stretch it, assuming that the polymer is virtually discharged from each of regions (hereinafter referred to as polymer non-discharge regions) from both ends of the aligned polymer discharge holes 5 extending in the TD width direction into which no polymer is discharged.

[0019] A die having such a second air ejection portion 7, 7' can be easily manufactured by modifying a die that stretches a polymer with high-speed air, such as a melt-blown die. Specifically, the polymer ejection holes in the desired non-polymer ejection region are blocked to prevent polymer ejection, while air is ejected from the air ejection portion as usual. With this modification, the air ejected from the air ejection portion corresponding to the non-polymer ejection region is ejected so as to hit the virtually ejected polymer from the non-polymer ejection region and stretch the virtually ejected polymer. Of course, a die having the second air ejection portion 7, 7' may also be designed from the beginning as a dedicated die.

[0020] The spinneret 2 also includes a polymer introduction pipe 8 communicating with the polymer discharge hole 5 and the polymer widening section 9, and air introduction pipes 10, 10' communicating with the first air discharge section 6 and the second air discharge sections 7, 7'.

[0021] The polymer discharge hole 5 is preferably cylindrical with a diameter of 0.1 mm to 0.7 mm, and the length of the discharge hole is preferably 1 mm to 10 mm, but can be appropriately determined taking into consideration the polymer viscosity, pressure loss due to the amount of polymer discharged from the nozzle, and processing limits.

[0022] The length W of the first air ejection section 6 in the TD direction is the range in which the first air ejection section 6 sandwiches each polymer ejection hole 5 from both sides in the MD direction. In other words, where the pitch between each polymer ejection hole 5 is P, the length W of the first air ejection section 6 = (number of ejection holes 5 - 1) × P.

[0023] The second air discharge sections 7, 7' are continuous with the first air discharge section 6. The lengths W1, W2 of the second air discharge sections 7, 7' are W1 ≥ 10 × P and W2 ≥ 10 × P, where P is the pitch between the polymer discharge holes 5, so that the polymer discharged from the polymer discharge holes 5 is uniformly stretched to both ends and falls into the collection section 3. Preferably, W1 ≥ 30 × P and W2 ≥ 30 × P, more preferably W1 ≥ 50 × P and W2 ≥ 50 × P. Furthermore, by making W1 ≤ 0.5W and W2 ≤ 0.5W relative to the length W of the first air discharge section, the high-speed air discharged from the first air discharge section can be prevented from spreading in the TD direction and propelled vertically. Furthermore, to achieve uniform dispersion in the TD direction within the nonwoven fabric device, it is preferable that W1 = W2.

[0024] A polymer supply pipe 8 and air introduction pipes 10, 10' are connected to the spinneret 2. The polymer, which is the raw material for the nonwoven fabric, is supplied from the polymer supply pipe 8, uniformly widened in the TD direction in the polymer widening section 9, and distributed to the polymer discharge holes 5. The air introduction pipes 10, 10' communicate with the first air discharge section 6 and the second air discharge sections 7, 7', and repeatedly widen and contract in the TD direction, until the air is discharged as uniform, high-speed air. Note that the spinneret 2 is not limited to the above-mentioned form.

[0025] The collecting section 3 is made of mesh or punched metal and is movable in the MD. The collecting section 3 also has an intake section (not shown). The polymer discharged from the spinneret 2 is collected and deposited while being sucked by the intake section. In order to reliably collect the polymer, the length of the collecting section 3 in the TD direction is preferably longer than the length W of the first air discharge section 6 in the TD direction. Note that the collecting section 3 is not limited to the above configuration, and any known configuration for collecting a stretched polymer may be applied.

[0026] The diffusion space 4 is a space where the polymer diffuses between the spinneret 2 and the collection section 3. Hereinafter, the airflow generated by the high-speed air discharged from the first air discharge section 6 and the second air discharge sections 7, 7' in the diffusion space 4 will be referred to as the transport flow. Also, the space in the diffusion space 4 where the transport flow is generated will be referred to as the travel path.

[0027] The nonwoven fabric manufacturing apparatus 1 is provided with a cylindrical partition wall 11 that is open on both vertical sides so as to surround the diffusion space 4. The partition wall 11 prevents the short fibers formed by stretching the polymer from flowing out of the apparatus, and at the same time, it facilitates control of the transport flow by controlling the inflow of air from the outside that causes turbulence in the transport flow.

[0028] Since the carrier flow spreads in a direction perpendicular to the flow (MD direction) as it approaches the collection section 3, the partition wall 11 may be inclined so that the diffusion space 4 expands vertically downward in order to rectify the carrier flow. In this case, if the inclination is greater than the spread of the carrier flow, the carrier flow becomes complicated and it becomes difficult to control the airflow, so the angle of inclination is preferably 0° to 30° with respect to the vertical line. Furthermore, the partition wall 11 may be made up of multiple surfaces connected without any gaps.

[0029] The distance L2 in the TD direction from the end of the second air discharge portion 7, 7' to the partition wall 11 preferably satisfies L2 / L1 ≥ 0.05, where L1 is the distance between the two partition walls 11 facing each other in the TD direction. When L2 / L1 is 0.05 or more, the differential pressure between the high-velocity air discharged from the second air discharge portion 7, 7' and the partition wall 11 does not become large, making it difficult for negative pressure to occur and stabilizing the flow of the transport air at the end.

[0030] In order to prevent the inflow of ambient air into the diffusion space 4, the vertical distance H2 from the upper end to the lower end of the partition wall 11 is preferably 80% to 120% of the distance H1 between the spinneret 2 and the collection section 3.

[0031] The nonwoven fabric manufacturing apparatus 1 is equipped with second air discharge units 7, 7' on the spinneret 2 in order to discharge high-speed air into the diffusion space 4 while uniformly distributing the velocity distribution of the transport flow in the TD direction. The second air discharge units 7, 7' are preferably arranged so that the first air discharge unit 6 and the second air discharge units 7, 7' are on the same straight line when viewed vertically downward, which is the polymer discharge direction from the polymer discharge holes 5. Furthermore, the first polymer discharge unit and the second polymer discharge unit are preferably arranged on the same straight line when viewed from a direction perpendicular to the polymer discharge direction and the spinneret width direction. Arranging the second air discharge units 7, 7' in this manner enhances the effect of the high-speed air discharged from the second air discharge units 7, 7' in assisting the attenuation of the high-speed air discharged from the first air discharge unit 6, thereby further suppressing the attenuation of the high-speed air from the first air discharge unit 6. As a result, the fibers discharged from the polymer discharge hole 5 and shortened to short fibers can be further prevented from diffusing before falling into the collection section 3.

[0032] [Second embodiment] Please refer to Figure 2. Figure 2 is a schematic diagram of a second embodiment of the nonwoven fabric manufacturing apparatus of the present invention. The left side of the page is a longitudinal cross-sectional view seen from the MD direction. The right side of the page is a cross-sectional view taken along the lines AA and BB of the left side of the page. In the second embodiment, the spinneret 2 is composed of three separable members: a first nozzle 12 having a polymer discharge hole 5 and a first air discharge section 6, a second nozzle 13 having one second air discharge section 7, and a second nozzle 13' having the other second air discharge section 7'. The rest is the same as the first embodiment.

[0033] The second nozzles 13, 13' do not have the function of discharging a polymer and only discharge air. The nozzle configuration is the same as that of the first nozzle 12, except that the polymer discharge hole 5, polymer supply pipe 8, and polymer widening section 9 are removed, and second air introduction pipes 14, 14' are provided to supply air to the second air discharge sections 7, 7'.

[0034] It is preferable that the shapes of the first nozzle 12 and the second nozzles 13, 13' be the same when observed from the TD direction. If the shapes are the same when observed from the TD direction, the spinneret 2 becomes a continuous structure, and the intake of entrained air from the MD direction can be uniform in the TD direction. Furthermore, the air velocity discharged from each of the second air discharge units 7, 7' may be the same as the air velocity discharged from the first air discharge unit 6. However, since the first air discharge unit 6 is connected to the air introduction pipes 10, 10', the second air discharge unit 7 is connected to the second air introduction pipe 14, and the second air discharge unit 7' is connected to the second air introduction pipe 14', the air velocity and air volume can be adjusted individually. The air velocity and flow rate can be freely adjusted according to the basis weight distribution. By making the air speed discharged from the first air discharge section 6 and the air speed discharged from each of the second air discharge sections 7, 7' the same, it is possible to reduce the pressure difference between the air discharged from the first air discharge section 6 and the air discharged from the second air discharge section 7, and the pressure difference between the air discharged from the first air discharge section 6 and the air discharged from the second air discharge section 7' ​​in the diffusion space 4, thereby minimizing the scattering of fibers. [Example]

[0035] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples.

[0036] [Examples 1 to 3, Comparative Example 1] In Examples 1 to 3 and Comparative Example 1, the distribution of the wind speed of the air discharged from the first air discharge part and the second air discharge part at a specific position in the diffusion space was obtained by fluid numerical analysis, and a comparison was made using the wind speed at a specified position directly below the discharge hole of the spinneret in the TD direction. The fluid numerical analysis was performed using STAR-CCM+ from Siemens K.K.

[0037] [Example 1] The analysis was performed using the embodiment shown in Figure 1. The dimensions were P = 1.3 mm, W = 263 mm, W1 = W2 = 118.5 mm, L1 = 600 mm, L2 = 50 mm, H1 = 1000 mm, and H2 = 800 mm. The air was discharged at a flow rate of 24.9 m / s both directly below the first air discharge port and directly below the second air discharge port.

[0038] [Example 2] The analysis was performed using the embodiment shown in Figure 2. The dimensions were P = 1.3 mm, W = 263 mm, W1 = W2 = 100 mm, L1 = 600 mm, L2 = 58.5 mm, H1 = 1000 mm, and H2 = 800 mm. The air was discharged at a flow rate of 25.6 m / s both directly below the first air discharge port and directly below the second air discharge port.

[0039] [Example 3] The analysis was performed using the embodiment shown in Figure 1. The dimensions were P = 1.3 mm, W = 263 mm, W1 = W2 = 50 mm, L1 = 600 mm, L2 = 237 mm, H1 = 1000 mm, and H2 = 800 mm. The air was discharged at a flow rate of 24.6 m / s both directly below the first air discharge port and directly below the second air discharge port.

[0040] [Comparative Example 1] The analysis was performed using the embodiment shown in Figure 3. The spinneret 2 in Figure 3 does not have a second air outlet. The dimensions were P = 1.3 mm, W = 263 mm, L1 = 600 mm, L2 = 168.5 mm, H1 = 1000 mm, and H2 = 800 mm. The air was discharged at a flow rate of 25.0 m / s directly below the first air outlet.

[0041] Table 1 shows the dimensional conditions of the nonwoven fabric manufacturing apparatuses of Examples 1 to 3 and Comparative Example 1, and Table 2 shows the wind speeds at each flow speed evaluation position obtained by fluid analysis.

[0042] [Table 1]

[0043] [Table 2]

[0044] Figure 4 is a longitudinal cross-sectional view seen from the MD direction, showing the flow velocity evaluation position in the fluid analysis. Figure 4 is a diagram in which the evaluation position has been added to Figure 1 of Example 1. Table 3 shows the coordinates, with the center of the spinneret 2 in the TD direction and the position of the first air discharge part 6 as the origin. The coordinates of the evaluation position are the same in Examples 2 and 3 and Comparative Example 1.

[0045] [Table 3]

[0046] To evaluate the distribution of flow velocity directly below the spinneret 2, the flow velocity is evaluated at evaluation position (2), which is directly below the center of the spinneret 2 in the TD direction, and at evaluation positions (1) and (3), which are directly below both ends of the spinneret 2 in the TD direction. In Comparative Example 1, the flow velocity is reduced by 88% at both evaluation positions (1) and (3) compared to evaluation position (2). On the other hand, in Example 1, the flow velocity is reduced by only 36% at both evaluation positions (1) and (3) compared to evaluation position (2), in Example 2, it is reduced by only 24%, and in Example 3, it is reduced by only 45%.

[0047] Next, to evaluate the distribution of flow velocity near the collection section 3, the flow velocity is evaluated at evaluation position (8), which is below the center of the spinneret 2 in the TD direction, and at evaluation positions (7) and (9), which are below both ends of the second air discharge section 7. In Comparative Example 1, the flow velocity at both evaluation positions (7) and (9) is reduced by 92% compared to evaluation position (8). On the other hand, in Example 1, the flow velocity at both evaluation positions (7) and (9) is reduced by only 54% compared to evaluation position (8), in Example 2, it is reduced by only 62%, and in Example 3, it is reduced by only 72%.

[0048] From the above results, it was found that in Examples 1 to 3, the decrease in the flow velocity below both ends of the spinneret 2 in the TD direction was suppressed.

[0049] Furthermore, when comparing the flow velocities at evaluation position (8) below the center of the spinneret 2 in the TD direction and near the collection section 3, the flow velocity in Comparative Example 1 is found to be greater than in Examples 1 to 3. This result can be explained by Figures 5 and 6. Figure 5 is a vertical cross-sectional view seen from the MD direction, showing the flow velocity in the fluid analysis. Figure 6 shows the same fluid analysis results as Figure 5, but in a different display format than Figure 5. As can be seen from the flow velocity distribution shown by vectors, in Comparative Example 1, the flow contracts significantly from both ends of the spinneret 2 in the TD direction toward the center of the spinneret 2.

[0050] [Examples 4 and 5, Comparative Example 2] In the following embodiments of [Example 2] and [Comparative Example 1], a polymer was actually discharged from the spinneret, and the scattering distribution in the collection section 3 was measured.

[0051] [Example 4] Measurement of the scattering distribution was performed using the embodiment shown in Figure 2. The dimensions were the same as in Example 2: P = 1.3 mm, W = 263 mm, W1 = W2 = 100 mm, L1 = 600 mm, L2 = 58.5 mm, H1 = 1000 mm, and H2 = 800 mm. The polymer used was a pullulan aqueous solution prepared by dissolving pullulan in water and adjusting the viscosity to 6000 mPa·sec. The spinneret had 159 polymer outlet holes 5, and the pullulan aqueous solution was discharged at a polymer discharge rate of 0.12 mL / min per hole. Air was supplied at 1000 L / min through the air inlet tube 10, which supplies air to the first air outlet 6, and the gap of the first air outlet 6 was adjusted so that the flow velocity of the first air outlet 6 was 22.0 m / s. In addition, 500 L / min of air was supplied to each of the second air introduction pipes 14, 14' that supply air to the second air outlets 7, 7', and the gap between the second air outlets 7, 7' was adjusted so that the flow rate of each of the second air outlets 7, 7' was 22.0 m / s.

[0052] [Example 5] The scattering distribution was measured under the same conditions as in Example 4, except that 1500 L / min of air was supplied to the air inlet pipe 10 that supplies air to the first air outlet 6, and the gap of the first air outlet 6 was adjusted so that the flow velocity of the first air outlet 6 was 34.0 m / s.

[0053] Comparative Example 2 Measurement of scattering distribution was performed using the embodiment shown in Figure 3. The dimensions were the same as those in Comparative Example 1, with P = 1.3 mm, 159 holes arranged, W = 263 mm, L1 = 600 mm, L2 = 168.5 mm, H1 = 1000 mm, and H2 = 800 mm. The polymer used was a pullulan solution prepared by dissolving pullulan in water and adjusting the viscosity to 6000 mPa·sec. The spinneret had 159 polymer outlet holes 5, and the pullulan solution was discharged at a polymer discharge rate of 0.12 mL / min per hole. Air was supplied at 1000 L / min through the air inlet tube 10, which supplies air to the first air outlet 6. The gap of the first air outlet 6 was adjusted so that the flow velocity of the first air outlet 6 was 22.0 m / s.

[0054] To evaluate the state of polymer scattering in the collection section 3, the pullulan aqueous solution was discharged from the spinneret 2, and the weight of the pullulan aqueous solution accumulated in the collection section 3 on a measuring scale (50 mm (TD) × 90 mm (MD)) divided into five sections with a width of 250 mm directly below the center of the spinneret in the TD direction was measured, and the basis weight variation was calculated using the following formula. -Basis weight variation = ((maximum measured value - minimum measured value) / (maximum measured value + minimum measured value)) x 100 The evaluation results of Examples 4 and 5 and Comparative Example 2 are shown in Table 4.

[0055] [Table 4]

[0056] In Comparative Example 1, which only had the first air outlet section, the basis weight variation was 20.5%, while in Example 4, in which the air flow velocity of the second air outlet section was the same as that of the first air outlet section, the basis weight variation was reduced to 14.3%. Furthermore, in Example 5, in which the air velocity of the first air outlet section was made faster than that of the second air outlet section, the basis weight variation was 16.9%.

[0057] From the above results, it has been found that by discharging air from the second air discharge section 7, it is possible to suppress a significant decrease in the flow rate near the collecting section 3 below both ends of the spinneret 2 in the TD direction. As a result, it is possible to suppress non-uniformity in the basis weight of the nonwoven fabric in the collecting section 3. Furthermore, by setting the air speeds of the first air discharge section and the second air discharge section to the same speed, it is possible to make the basis weight uniform. [Industrial Applicability]

[0058] The nonwoven fabric manufacturing apparatus of the present invention can be used to manufacture nonwoven fabric. [Explanation of symbols]

[0059] 1. Nonwoven fabric manufacturing equipment 2 spinneret 3. Collection section 4 Diffusion Space 5 Polymer discharge hole 6 First air outlet 7, 7' Second air outlet 8 Polymer supply pipe 9 Polymer widening section 10, 10' air intake pipe 11 Partition Wall 12 First nozzle 13, 13' Second nozzle 14, 14' Second air intake pipe W Length of the first air outlet W1, W2 Length of the second air outlet H1 Vertical distance between the spinneret and the collection section H2 Vertical distance of partition wall L1 Distance of partition wall in TD direction L2: Distance between the partition wall and the spinneret P Discharge hole pitch

Claims

1. A nonwoven fabric manufacturing apparatus comprising a nozzle for discharging a fiberized polymer and a collection section for collecting the fiberized polymer, The nozzle is a plurality of polymer discharge holes arranged in a row in the width direction of the nozzle; a first air ejection section that ejects air onto the polymer ejected from the polymer ejection hole to stretch the polymer and turn it into fiber; a pair of second air ejection sections which are regions in which no polymer is ejected and which extend in the width direction of the nozzle from both ends of the polymer ejection holes arranged in a row, and which eject air so as to hit the virtually ejected polymer and stretch the virtually ejected polymer, assuming that a polymer is virtually ejected from each of the regions, where W1 and W2 are lengths of the second air ejection portions in the nozzle width direction, and P is the pitch of the polymer ejection holes arranged in a row, and W1 ≥ 10 × P and W2 ≥ 10 × P are satisfied. Nonwoven fabric manufacturing equipment.

2. 2. The nonwoven fabric manufacturing apparatus according to claim 1, wherein the length of the first air ejection section is W, and W1≦0.5W and W2≦0.5W are satisfied.

3. 2. The nonwoven fabric manufacturing apparatus according to claim 1, further comprising a partition wall surrounding a path along which the polymer travels from the spinneret to the collecting section.

4. 4. The nonwoven fabric manufacturing apparatus of claim 3, wherein L2 / L1≧0.05 is satisfied, where L1 is the distance between the two partition walls facing each other in the width direction of the die, and L2 is the distance in the width direction of the die from the end of the second air discharge portion to the partition wall.

5. 2. The nonwoven fabric manufacturing apparatus of claim 1, wherein the first air ejection portion and the second air ejection portion are on the same straight line when viewed from the polymer ejection direction, and the first air ejection portion and the second air ejection portion are on the same straight line when viewed from a direction perpendicular to the polymer ejection direction and the nozzle width direction.

6. 2. The nonwoven fabric manufacturing apparatus according to claim 1, wherein the die can be divided into a member having the first air ejection portion, a member having one of the second air ejection portions, and a member having the other second air ejection portion.

7. A method for producing a nonwoven fabric using the nonwoven fabric production apparatus of claim 6, wherein the flow velocity of the air discharged from the first air discharge portion and the flow velocity of the air discharged from the second air discharge portion are set to be the same.

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