Nonwoven fabric manufacturing device

Abstract

To provide a nonwoven fabric manufacturing device capable of manufacturing a nonwoven fabric having excellent basis weight uniformity in a width direction.SOLUTION: A nonwoven fabric manufacturing device of the invention comprises: a die having a plurality of nozzles, which are aligned in a line and discharge polymer, and a first air discharge part to discharge air for drawing polymer discharged from the nozzles; a collection part to collect the fiberized polymer; and a pair of second air discharge parts that discharge air toward the same direction as the polymer discharge direction. Air discharge ports of the second air discharge parts are located on both outsides in a nozzle alignment direction.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an apparatus for manufacturing a nonwoven fabric. [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-speed air, allowing for the production of nonwoven fabrics with finer fibers, around 1 μm in diameter, compared to other manufacturing methods. This makes it suitable for a wide range of applications, including hygiene materials, air filters, soundproofing materials, and secondary battery separators. In the meltblown process, the fibers dispersed in the air after stretching using high-speed air are then collected and deposited. Therefore, technology to control the airflow that disperses the fibers 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 due to a viscous effect known as the Coanda effect, making it possible to control the polymer dispersion state 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 transport direction, and does not assume control of the flow in the width direction, which is wider than the transport 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, the flow velocity of the air toward the collection section decreases from the widthwise edges of the nonwoven fabric due to frictional resistance with the surrounding air and wall surfaces before the polymer and air are discharged from the nozzle and collected. 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. As a result, the nonwoven fabric after collection 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 decreases further, 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 fibers 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, comprises: a die having a plurality of nozzles that discharge a polymer arranged in a line and a first air discharge unit that discharges air to stretch the polymer discharged from the nozzles; a collecting section that collects the polymer discharged from the nozzle and turned into fiber; a pair of second air ejection units that eject air in the same direction as the polymer ejection direction from the nozzle; When observed from a direction perpendicular to the nozzle arrangement direction and the polymer discharge direction, the air discharge ports of the second air discharge section are located on both sides of the line extending downstream in the polymer discharge direction from the nozzles at both ends of the plurality of nozzles.

[0012] The nonwoven fabric manufacturing apparatus of the present invention preferably has any one of the following configurations [2] to [6]. [2] The nonwoven fabric manufacturing apparatus according to [1], further comprising a partition wall surrounding the path of the polymer from the nozzle to the collecting section. [3] The nonwoven fabric manufacturing apparatus according to [2], wherein the air outlet of the second air outlet section is located inside the area surrounded by the partition wall. [4] The nonwoven fabric manufacturing apparatus according to [3], further comprising a partition plate that closes the opening of the partition wall on the side closer to the nozzle except for the path of the polymer, and the air discharge port of the second air discharge unit is located downstream of the partition plate in the polymer discharge direction. [5] The nonwoven fabric manufacturing apparatus according to any one of [1] to [4] above, wherein the air outlet of the second air outlet section is composed of a single hole or a plurality of holes. [6] The nonwoven fabric manufacturing apparatus according to any one of [1] to [4] above, wherein the air outlet of the second air outlet section is slit-shaped. [Effects of the Invention]

[0013] 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]

[0014] [Figure 1] 1 is a schematic diagram of a first embodiment of a nonwoven fabric manufacturing apparatus of the present invention, and is a longitudinal cross-sectional view seen from the MD direction. [Figure 2] FIG. 2 is a schematic diagram of a second embodiment of the nonwoven fabric manufacturing apparatus of the present invention, and is a longitudinal cross-sectional view seen from the MD direction. DETAILED DESCRIPTION OF THE INVENTION

[0015] 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.

[0016] [First embodiment] Please refer to Figure 1. Figure 1 is a schematic diagram of a first embodiment of the nonwoven fabric manufacturing apparatus of the present invention, and is a longitudinal cross-sectional view seen from the MD. The nonwoven fabric manufacturing apparatus 1 includes a spinneret 2, a collection section 3 that accumulates and collects the stretched polymer, and a diffusion space 4 where the polymer diffuses from the spinneret 2 toward the collection section 3.

[0017] The spinneret 2 is equipped with a plurality of polymer discharge nozzles 5 arranged in a row that discharge the polymer, which is the raw material for the nonwoven fabric, and a first air discharge section 6 that discharges high-speed air to stretch the polymer. The polymer discharge nozzle 5 is preferably cylindrical with a diameter of 0.1 mm to 0.7 mm, and the nozzle length is preferably 3 mm to 10 mm, although this can be determined appropriately taking into consideration the polymer viscosity and pressure loss due to the amount of polymer discharged from the nozzle.

[0018] Each polymer discharge nozzle 5 is surrounded by cylindrical air nozzles that share the same central axis as the polymer discharge nozzle 5. In other words, there are the same number of cylindrical air nozzles as the polymer discharge nozzles 5, and these air nozzles together constitute the first air discharge section 6. Each air nozzle of the air discharge section 6 is preferably cylindrical with a diameter of 1 mm to 4 mm to uniformly stretch the polymer. The nozzle pitch of the polymer discharge nozzle 5 and the first air discharge section 6 is preferably equal to or greater than the cylindrical diameter of the first air discharge section 6 but within 7 mm to improve dispersion of the transport flow and polymer in the TD direction.

[0019] The polymer is stretched by uniformly blowing high-speed air around the polymer discharged from each polymer discharge nozzle 5. To stably stretch the polymer, the lower end of the first air discharge part 6 is positioned vertically at the same position as or below the lower end of the polymer discharge nozzle 5, and the difference in vertical position is preferably within 3 mm.

[0020] A polymer introduction pipe 7 and a first air introduction pipe 8 are connected to the spinneret 2. The polymer, which is the raw material for the nonwoven fabric, is equally distributed to each polymer discharge nozzle 5 via the polymer introduction pipe 7 and discharged toward the diffusion space 4. Air for stretching the polymer is introduced into the first air discharge section 6 via the first air introduction pipe 8 and is discharged as high-speed air to stretch the polymer. Note that the spinneret 2 is not limited to the above-mentioned form.

[0021] The collecting section 3 is made of mesh or punched metal and is movable in the MD direction. The collecting section 3 also has an air intake section (not shown). The polymer discharged from the polymer discharge nozzle 5 of the spinneret 2 is collected and deposited while being sucked by the air intake section. To ensure reliable collection of the polymer, the length of the collecting section 3 in the TD direction is preferably longer than the distance L1 connecting the outermost points in the TD direction of the entire first air discharge section 6. Note that the collecting section 3 is not limited to the above-mentioned configuration, and any known configuration for collecting a stretched polymer may be used.

[0022] The diffusion space 4 is a space in which the polymer diffuses between the polymer discharge nozzle 5 of the spinneret 2 and the collection section 3. Hereinafter, the airflow generated by the high-speed air from the first air discharge section 6 in the diffusion space 4 will be referred to as the transport flow. Also, the space in which the transport flow is generated in the diffusion space 4 will be referred to as the travel path.

[0023] The nonwoven fabric manufacturing apparatus 1 is equipped with a second air discharge section 10 within the diffusion space 4 in order to uniformize the velocity distribution of the transport flow in the TD direction. The second air discharge sections 10 are provided on both outer sides of the die, which corresponds to the TD direction in FIG. 1 , that is, the direction in which the polymer discharge nozzles 5 are arranged and the direction perpendicular to the polymer discharge direction from the polymer discharge nozzles 5. A second air introduction pipe 11 is connected to the second air discharge section 10. The second air discharge section 10 discharges air in the same direction as the polymer discharge nozzles 5 are facing.

[0024] The air discharged from the second air discharge unit 10 is set to have a higher discharge flow velocity than the carrier flow. The faster the flow velocity, the lower the static pressure, resulting in a lower static pressure than the carrier flow. Due to the effect of the low-pressure area attracting the surrounding fluid, the air discharged from the first air discharge unit 6 is drawn outward in the TD direction, causing the carrier flow and polymer to diffuse outward in the TD direction. As a result, compared to when there is no air from the second air discharge unit 10, the polymer is collected in the collection unit 3 in a state where it is more diffused in the TD direction. Since the static pressure decreases as the air flow velocity increases, the flow velocity of the air discharged from the second air discharge unit 10 is preferably 110% to 150% of the air flow velocity of the first air discharge unit 6. Furthermore, since excessive addition of flow rate may cause turbulence in the transport flow, the flow rate range of the air flow rate ejected from one second air ejection section 10 is preferably 10% to 20% of the air flow rate of the first air ejection section 6, i.e., the total amount of air flow rates from all the air nozzles that make up the first air ejection section 6.

[0025] The shape of the outlet of the second air ejection unit 10 may be a single hole or multiple holes. From the viewpoint of generating a stable air flow, the shape of the outlet of the second air ejection unit 10 is preferably a slit shape.

[0026] The center-to-center distance L2 between the two second air ejection sections 10 is preferably 110% to 150% of the distance L1. By locating the second air ejection section 10 at a position where it does not interfere with the conveyed flow, the desired effect is more easily obtained. Furthermore, the vertical distance H2 from the lower end of the second air ejection section 10 to the collection section 3 is preferably 80% to 100% of the vertical distance H1 from the lower end of the first air ejection section 6 to the collection section 3. When the distance H2 is within this range, the distance H2 is not too small compared to the distance H1, making it easier to obtain the desired effect.

[0027] The nonwoven fabric manufacturing apparatus 1 is provided with a cylindrical partition wall 9 that is open on both vertical sides so as to surround the diffusion space 4. The partition wall 9 prevents 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 as it approaches collection section 3, partition wall 9 may be inclined so that diffusion space 4 expands vertically downward to straighten the carrier flow. In this case, if the inclination is greater than the air spread, the carrier flow becomes complicated and it becomes difficult to control the airflow, so the angle of inclination is preferably 0° to 10° with respect to the vertical line. Furthermore, partition wall 9 may be made up of multiple surfaces connected without any gaps.

[0029] In order to suppress turbulence in the transport flow, the shape of the inner periphery of the partition wall 9 at each vertical position is preferably a rectangle with sides in both the MD and TD directions, and the inclination angles of the opposing faces across the diffusion space 4 relative to the vertical line are preferably the same. Furthermore, because the transport flow expands outward in the TD direction toward the collection section 3, the distance between opposing partition walls 9 in the TD direction is preferably greater than the distance L1, and even preferably within 250% of the distance L1. Furthermore, the width of the partition wall 9 in the MD direction is preferably 20% to 100% of its width in the TD direction. In order to suppress the inflow of ambient air into the diffusion space 4, the vertical distance H3 from the upper end to the lower end of the partition wall 9 is preferably 80% to 120% of the distance H1. Furthermore, with regard to the installation position of the partition wall 9, it is preferable that the vertical distance between the lower end of the partition wall 9 and the collection section 3 is within 20% of the distance H1, and it is preferable that the vertical distance between the upper end of the partition wall 9 and the lower end of the polymer discharge nozzle 5 is within 20% of the distance H1.

[0030] [Second embodiment] Please refer to Fig. 2. Fig. 2 is a schematic diagram of a second embodiment of the nonwoven fabric manufacturing apparatus of the present invention, and is a longitudinal cross-sectional view seen from the MD. The second embodiment is the same as the first embodiment except that a partition plate 12 is further provided.

[0031] Partition plate 12 is installed horizontally so as to close the opening of partition wall 9 on the side closer to polymer discharge nozzle 5, except for the polymer travel path. Partition plate 12 prevents the polymer from flowing out of the apparatus and controls the amount of external gas flowing into diffusion space 4, thereby enhancing the effect of partition wall 9, which facilitates control of the transport flow.

[0032] The high-speed air discharged from the first air discharge section 6 draws in the surrounding fluid due to a drop in static pressure, especially immediately after discharge. If the accompanying airflow from the upper part of the diffusion space 4 completely disappears, there is a concern that a vortex will be generated within the diffusion space 4 toward the first air discharge section 6, complicating the air flow. Therefore, the partition plate 12 is preferably located vertically below the polymer discharge nozzle 5 and the first air discharge section 6 of the spinneret 2. Furthermore, to obtain the desired effect of the partition plate 12, the vertical distance from the partition plate 12 to the lower end of the first air discharge section 6 is preferably 5 mm to 50 mm. The second air discharge section 10 is located vertically below the partition plate 12, and the vertical distance from the lower end of the second air discharge section 10 to the partition plate 12 is preferably within 15% of the distance H1. [Example]

[0033] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples. The physical properties of the obtained nonwoven fabric were measured by the following methods.

[0034] 1.Weight [g / m 2 ] A test piece measuring 500 mm (MD) x 180 mm (TD) was taken from the nonwoven fabric. At this time, the center of the nonwoven fabric and the taken test piece in the TD direction were aligned. The mass [g] of the taken test piece was measured using a top-pan electronic balance (manufactured by Ohaus Co., Ltd.) and 2 Converted to mass per unit [g / m 2 ].

[0035] 2. Weight variation [%] A total of 90 20mm (MD) x 20mm (TD) test pieces were taken from the nonwoven fabric, 10 rows in the MD direction and 9 rows in the TD direction. These were continuous rows on the nonwoven fabric. The center of the row taken in the TD direction was aligned with the center of the nonwoven fabric in the TD direction. The mass [g] of the taken test pieces was measured using a top-pan electronic balance (Ohaus), and the average mass and standard deviation for each row in the MD and TD directions were calculated. The standard deviation was divided by the average value and multiplied by 100 to determine the basis weight variation [%], and the basis weight variation in the MD and TD directions, respectively, was calculated.

[0036] [Example 1] A nonwoven fabric was obtained using the embodiment shown in Figure 2. The diameter of the polymer discharge nozzle was 0.3 mm, and each air nozzle constituting the first air discharge section was a cylindrical nozzle with a hole diameter of 3 mm surrounding each polymer discharge nozzle. 41 polymer discharge nozzles were arranged in the TD direction, with each pitch set to 5 mm. The total flow rate of air discharged from each air nozzle constituting the first air discharge section was 1.8 m 3 The air flow rate from the second air outlet was 0.1 m / min. 3 / min, total 0.2m 3 / min. The center-to-center distance L2 between the second air ejection portions on both outer sides of the nozzle in the TD direction was set to approximately 300 mm.

[0037] The partition wall is made up of four faces, each parallel to either the MD or TD direction. The faces parallel to the TD direction are symmetrically inclined so that the diffusion space expands vertically downward, with an angle of approximately 3° relative to the vertical line.

[0038] The collection part had a collection surface made of punched metal with an opening ratio of 32.6%, and was installed approximately 1000 mm vertically below the first air ejection part.

[0039] The polymer discharged from the polymer discharge nozzle was an aqueous solution of 20% pullulan dissolved in purified water with a viscosity of approximately 5400 mPa·s. The aqueous solution discharged from the polymer discharge nozzle was stretched to spin the polymer, and the polymer was collected on the collecting surface of the collection unit.

[0040] In addition, in order to dry the spun polymer before collection, an infrared heater of approximately 500°C (not shown) was installed in the diffusion space except for the polymer travel path, and the ambient temperature in the diffusion space was set to approximately 100°C.

[0041] [Comparative Example 1] A nonwoven fabric was obtained in the same manner as in Example 1, except that the flow rate of air discharged from the second air discharge part was set to 0. The obtained nonwoven fabric was evaluated by the methods described above.

[0042] The evaluation results of Example 1 and Comparative Example 1 are shown in Table 1.

[0043] [Table 1]

[0044] The variation in basis weight in the MD direction of Example 1 was 4.8%, and the variation in basis weight in the TD direction was 6.7%. On the other hand, the variation in basis weight in the MD direction of Comparative Example 1 was 4.8%, and the variation in basis weight in the TD direction was 9.8%. This shows that Example 1 has improved uniformity of basis weight in the TD direction compared to Comparative Example 1.

[0045] Therefore, the nonwoven fabric manufacturing apparatus according to this embodiment is suitable for manufacturing nonwoven fabric with improved uniformity of basis weight in the TD direction. [Industrial Applicability]

[0046] The nonwoven fabric manufacturing apparatus of the present invention can be used to manufacture nonwoven fabric. [Explanation of symbols]

[0047] 1. Nonwoven fabric manufacturing equipment 2 spinneret 3. Collection section 4. Diffusion Space 5 Polymer discharge nozzle 6 First air outlet 7 Polymer introduction tube 8 First air inlet pipe 9 Partition Wall 10 Second air outlet 11 Second air introduction pipe 12 Horizontally installed partition board H1 Vertical distance between the first air outlet and the collection surface H2 Vertical distance between the second air outlet and the collection surface H3 Vertical distance from top to bottom of partition wall L1: The distance connecting the outermost points in the TD direction in the entire first air discharge section 6 L2 Center distance between the second air outlets

Claims

1. a die including a plurality of nozzles arranged in a row that eject a polymer and a first air ejection unit that ejects air to stretch the polymer ejected from the nozzles; a collecting section that collects the polymer discharged from the nozzle and turned into fiber; a pair of second air ejection units that eject air in the same direction as the polymer ejection direction from the nozzle, when observed from a direction perpendicular to the nozzle arrangement direction and the polymer discharging direction, the air discharge ports of the second air discharge unit are located on both outer sides in the nozzle arrangement direction of a line extending from both end nozzles of the plurality of nozzles to a downstream side in the polymer discharging direction; Nonwoven fabric manufacturing equipment.

2. 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 nozzle to the collecting section.

3. 3. The nonwoven fabric manufacturing apparatus according to claim 2, wherein the air outlet of the second air outlet section is located inside the area surrounded by the partition wall.

4. a partition plate that closes an opening of the partition wall near the nozzle except for a path through which the polymer travels; an air discharge port of the second air discharge unit is located downstream of the partition plate in the polymer discharge direction; The nonwoven fabric manufacturing apparatus according to claim 3.

5. 2. The nonwoven fabric manufacturing apparatus according to claim 1, wherein the air outlet of the second air outlet section is configured as a single hole or a plurality of holes.

6. 2. The nonwoven fabric manufacturing apparatus according to claim 1, wherein the air outlet of the second air outlet section is slit-shaped.

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