JP2023055090A - Production method of nonwoven fabric - Google Patents

Abstract

A nonwoven fabric manufacturing method and manufacturing apparatus capable of suppressing a temperature drop in a spinning space are provided.
A spinning process in which a molten thermoplastic resin is discharged from a spinning nozzle to form fibers, and the fibers are sucked in a plurality of suction areas arranged from the upstream side in the machine flow direction and collected on a collecting surface. and depositing the fibers as the collection surface moves downstream, wherein the plurality of suction areas controls the suction force on the upstream side to be smaller than that on the downstream side. A method of manufacturing a nonwoven fabric, including regions, and a manufacturing apparatus for use in the method.
[Selection drawing] Fig. 1

Description

The present invention relates to a method for producing nonwoven fabrics.

Nonwoven fabrics are used in various fields, and various proposals have been made for techniques related to their production methods. For example, Patent Literatures 1 to 3 describe manufacturing methods in which spun fibers are sucked and collected using a spinning nozzle to form a nonwoven fabric, which is conveyed by a conveyor.

JP 2012-154009 A JP 2013-249566 A Japanese Unexamined Patent Application Publication No. 2013-204208

In the method for producing a nonwoven fabric by spinning as described above, generally, the fibers are collected while the collecting surface is sucked from the side opposite to the spinning side. However, since the fibers are gradually collected and deposited as they move downstream in the conveying direction, the amount of outside air taken in by suction becomes larger on the upstream side than on the downstream side. Due to the difference in the amount of outside air taken in, the temperature on the upstream side becomes lower than that on the downstream side, and the drawing ability of the spun fibers accompanying the suction on the upstream side decreases, and the diameter of the fiber tends to increase.

In view of the circumstances described above, the present invention relates to a method for producing a nonwoven fabric that suppresses a temperature drop in the spinning space.

The present invention comprises a spinning process in which molten thermoplastic resin is discharged from a spinning nozzle to form fibers, and the fibers are sucked in a plurality of suction areas arranged from the upstream side in the machine flow direction and collected on a collecting surface. and depositing the fibers as the collection surface moves downstream, wherein the plurality of suction areas controls the suction force on the upstream side to be smaller than that on the downstream side. A method of making a nonwoven fabric is provided that includes regions.

Further, the present invention provides a spinning apparatus having a plurality of spinning nozzles for discharging a molten thermoplastic resin, sucking the fibers discharged from the plurality of spinning nozzles and collecting them on a collecting surface, and and a collection device that deposits the fibers as the fibers move downstream, and the plurality of spinning nozzles include a first spinning nozzle provided on the upstream side, and a first spinning nozzle provided on the downstream side of the first spinning nozzle. a second spinning nozzle provided, wherein the collecting device comprises a plurality of suction areas, including a first suction area corresponding to the first spinning nozzle and a second suction area corresponding to the second spinning nozzle Provided is a nonwoven fabric manufacturing apparatus having a suction force control mechanism that has regions and that makes the suction force of the first suction region and the suction force of the second suction region different.

According to the method for producing a nonwoven fabric of the present invention, it is possible to suppress the temperature drop in the spinning space. Moreover, the method for producing a nonwoven fabric of the present invention can be suitably carried out using the apparatus for producing a nonwoven fabric of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS It is a schematic diagram which shows one preferable structural example of the manufacturing apparatus used for the manufacturing method of the nonwoven fabric of this invention. It is the top view which looked at the belt conveyor of one structural example in ID direction. FIG. 4 is a perspective view schematically illustrating a communicating portion provided in a partition plate; It is the top view which looked at the belt conveyor of another structural example in ID direction.

BEST MODE FOR CARRYING OUT THE INVENTION A preferred embodiment of the method for producing a nonwoven fabric according to the present invention will be described below with appropriate reference to the drawings. However, the scope of the present invention is not limited to the forms exemplified below.
In this specification, the machine flow direction (conveyance direction) of the manufacturing apparatus at the time of manufacturing the nonwoven fabric is referred to as the MD direction (Machine Direction), and the width direction (perpendicular direction) perpendicular to the machine flow direction is referred to as the CD direction (Cross Direction). Say. A direction orthogonal to the MD direction and the CD direction, that is, the ejection direction of a spinning nozzle, which will be described later, is referred to as an ID direction (injection direction).

The method for producing a nonwoven fabric according to the present embodiment includes a spinning step and a fiber collection step.
The spinning step is a step of ejecting a molten thermoplastic resin from a spinning nozzle to form fibers. In the collecting step, the fibers are sucked in a plurality of suction regions arranged from the upstream side in the machine flow direction (the flow direction of the manufacturing apparatus) to collect them on the collecting surface, and the fibers are collected on the downstream side of the collecting surface. It is a step of depositing the fibers together with the movement. The above-described spinning process and collecting process are performed respectively in the spinning device 10 and the collecting device 20 in a preferred configuration example of the production device 100 shown in FIG.
First, the manufacturing apparatus shown in FIG. 1 will be described below. Next, the suction area in the nonwoven fabric manufacturing method of the present embodiment will be described.

A manufacturing apparatus 100 according to the present embodiment shown in FIG. 1 has a spinning device 10 and a collecting device 20 as illustrated in FIG. The spinning apparatus 10 has an extruder 11 , a gear pump 12 , a manifold 13 and a spinning device 14 .

The extruder 11 is a device that melts a thermoplastic resin (polymer) and extrudes the melted thermoplastic resin (hereinafter referred to as molten polymer) to the gear pump 12 side. As the thermoplastic resin to be melted by the extruder 11, those commonly used as materials for nonwoven fabrics can be used without particular limitation. The extruder 11 has, for example, a barrel (not shown) with a built-in screw and a raw material charging section. A thermoplastic resin is supplied, for example, in the form of pellets into the extruder 11 from a raw material input port, heated by the extruder 11 to become a molten polymer, and the molten polymer is supplied from the extruder 11 to the spinning device 14 via the gear pump 12. be done. The thermoplastic resin to be supplied into the extruder 11 may be prepared by directly charging the thermoplastic resin and optionally blended components into the extruder 11 instead of pellets.

Gear pump 12 is a pump that continuously delivers metered amounts of molten polymer to spinning device 14 . The gear pump 12 has a first gear pump 121 and a second gear pump 122, as illustrated in FIG. The first gear pump 121 sends the molten polymer supplied from the extruder 11 to a first spinning device 141 and a second spinning device 142 which will be described later. Similarly, the second gear pump 122 sends the molten polymer supplied from the extruder 11 to a third spinning device 143 and a fourth spinning device 144 which will be described later.

Manifold 13 is a support member that supports spinning device 14 . The manifold 13 has a first manifold 131 and a second manifold 132 as illustrated in FIG. The first manifold 131 is provided on the upstream side in the MD direction, and the second manifold 132 is provided on the downstream side in the MD direction. The first manifold 131 supports a first spinning device 141 and a second spinning device 142, and the second manifold 132 supports a third spinning device 143 and a fourth spinning device 144, which will be described later.

A spinning device 14 is connected to the extruder 11 via a gear pump 12 . The spinning device 14 is supplied with molten polymer from the extruder 11 via the gear pump 12 . The spinning device 14 has a spinning nozzle L for discharging molten polymer at its tip. A plurality of spinning nozzles L may be arranged at regular intervals in the CD direction to form a nozzle row.
Thus, the spinning device 10 has a plurality of spinning nozzles for discharging molten thermoplastic resin.

The spinning nozzle L ejects the molten polymer in the ID direction orthogonal to the MD direction and the CD direction. Fibers are formed from the molten polymer expelled from the spinning nozzle L. Various methods can be used to form fibers, for example, hot air drawing, electric field drawing, or the like is performed to form fibers. The fibers are collected and deposited on a collection surface by suction, which will be described later, and the fibers are entangled with each other to form a nonwoven fabric.

As illustrated in FIG. 1, the spinning device 14 has a first spinning device 141, a second spinning device 142, a third spinning device 143, and a fourth spinning device 144 from the upstream side in the MD direction. The first spinning device 141 and the second spinning device 142 are provided in the first manifold 131 on the upstream side in the MD direction, and the third spinning device 143 and the fourth spinning device 144 are provided in the second manifold 132 on the downstream side in the MD direction. be done. The first to fourth spinning devices 141 to 144 are provided with spinning nozzles L1 to L4, respectively. The MD direction, CD direction, and ID direction shown in FIG. 1 are three axial directions that are orthogonal to each other, and are common in all the drawings illustrated below. Moreover, the number of spinning nozzles arranged in the MD direction is not limited to that shown in FIG. 1, and can be set as appropriate.

The collection device 20 has a belt conveyor 21 and a suction power unit 22 that serve as a fiber collection surface. Thereby, the collection device 20 sucks the fibers discharged from the plurality of spinning nozzles, collects them on the collection surface, and deposits the fibers as the collection surface moves downstream.

The belt conveyor 21 has conveyor rolls 211 and belts 212 . Belt 212 is supported by conveyor rolls 211 to form a loop. By rotating the conveyor roll 211, it is configured to move from the upstream side to the downstream side in the MD direction on the upper surface side facing the spinning device. Therefore, the collection surface 212S, which is the surface on the upper surface side of the belt 212, moves from the upstream side to the downstream side in the MD direction. The belt 212 that has reached the conveyor roll 211 on the downstream side is reversed on the lower surface side and returns to the conveyor roll 211 on the upstream side. The deposited fibers 8 are stripped from the belt on the downstream side and moved to further downstream rolls. The belt 212 is typically a mesh belt, but its type is not particularly limited as long as it can collect the molten polymer discharged from the spinning device 14 .

The belt conveyor 21 of this embodiment has a plurality of suction sections 213 in the inner space between the upper surface side and the lower surface side of the looped belt 212 . The plurality of suction sections 213 are arranged in a grid pattern along the MD and CD directions, as shown in FIG. The suction section 213 is a space defined by a plurality of partition plates B arranged in a grid. Note that the suction section 213 is an example of a "suction space". Also, in FIG. 2, the illustration of the belt 212 is omitted for convenience of explanation.

In the present embodiment, as illustrated in FIG. 2, suction regions E11 to E15 are formed that are aligned in the MD direction. These suction areas E11 to E15 each include a plurality of suction sections 213 and extend along the CD direction, and as will be described later, are a plurality of suction areas arranged from the upstream side in the machine flow direction. Hereinafter, the suction areas E11 to E15 will simply be referred to as a suction area E when there is no particular need to distinguish between them.

The suction area E15 is configured by a plurality of suction sections 213 positioned most downstream in the MD direction among the plurality of suction sections 213 . The suction area E15 corresponds to the spinning nozzle 4 of the fourth spinning device 144. FIG. The suction area E14 is composed of a plurality of suction sections 213 positioned downstream and adjacent to the suction area E15. The suction area E14 corresponds to the spinning nozzle 3 of the third spinning device 143.
The suction region E13 is composed of a plurality of suction sections 213 positioned downstream and adjacent to the suction region E14. The suction area E13 is between the third spinning device 143 and the second spinning device 142 and does not correspond to any spinning nozzle.
The suction area E12 is composed of a plurality of suction sections 213 positioned downstream and adjacent to the suction area E13. The suction area E<b>12 corresponds to the spinning nozzle L<b>2 of the second spinning device 142 . The suction area E11 is configured by a plurality of suction sections 213 positioned most upstream in the MD direction among the plurality of suction sections 213 . The suction area E<b>11 corresponds to the spinning nozzle L<b>1 of the first spinning device 141 .
The number of suction areas E and the number of suction sections 213 arranged in the MD direction are not limited to those shown in FIG. 2, and can be set as appropriate.

Here, among the plurality of partition plates B, each of the plurality of partition plates B1 extending in the MD direction is provided with a communication hole 215 as illustrated in FIG. The communication hole 215 is provided in a portion of the partition plate B1 that partitions the suction sections (suction spaces) 213 adjacent to each other in the CD direction. As a result, each of the plurality of suction sections (suction spaces) 213 forming the suction regions E11 to E15 communicate with each other in the CD direction.

The suction power section 22 includes a plurality of suction blowers 221 . The suction blower 221 is a device that is connected to each of the suction areas E11 to E15 and sucks them. In FIG. 2, the suction blower 221 is connected in the CD direction to the outermost suction section 213 in the CD direction of each of the suction areas E11-E15.
In the collecting device 20, the suction force by the suction blower 221 is controlled to be different in each of the suction areas E11 to E15. The suction force is controlled by a suction force control mechanism. The "suction force" is, for example, the air volume (suction air volume) with which the suction blower 221 sucks the suction area E, and the same applies to the following description.

The suction force control mechanism described above is, for example, the following mechanism.
The suction control mechanism of the first mode is a mechanism provided in the suction power unit 22 itself. That is, an individual suction blower 221 is connected to each of the suction areas E11 to E15, and the suction force is independently controlled for each suction area (not shown). By making the suction power of each suction blower 221 different, the suction power in the suction areas E11 to E15 is made different.
The suction control mechanism of the second mode is a mechanism for varying the opening area of the communication hole 215 arranged for the communication hole 215 of each partition plate B1. As the variable mechanism, various mechanisms that can appropriately change the size (opening area) of the open area 215a of the communication hole 215 can be employed. For example, a set of shielding plates with different sizes of shielding areas can be mentioned. A shielding plate with a large shielding area is installed in the communication hole 215 to narrow the opening area, and a shielding plate with a small shielding area is installed or shielded against the suction area where the suction force is to be increased. To relatively widen the opening area without installing a plate. Alternatively, the shielding plate may have a shutter function, and the aperture of the shutter may be appropriately controlled from outside the collection device 20 . A suction control mechanism using such shielding plates can control the suction forces in the suction regions E11 to E15 to be different. In the suction control mechanism of the second aspect, the number of suction blowers 221 can be made smaller than in the suction control mechanism of the first aspect. In this case, for example, as shown in FIG. 2, two suction blowers 221 are connected to each of the suction areas E11 to E15 from both ends of the suction/suction area E in the CD direction, and while sucking these entire areas, the two suction blowers 221 are connected to each other. It is possible to vary the suction force for each of the suction regions E11 to E15 by means of a mechanism for varying the hole area.

In the collection device 20, the connection direction of the suction blower 221 to the suction areas E11 to E15 is not limited to the CD direction as shown in FIG. 2, and may be the ID direction. In the case of the ID direction, it is preferable to connect from the bottom side of the suction area E (the side opposite to the spinning nozzle L). In this case, from the viewpoint of better collection of the spun fibers, it is preferable to connect the outermost suction section 213 in the CD direction of each of the suction regions E11 to E15 from the lower surface side in the ID direction.

Patterns for different suction forces in the present embodiment include various combinations of suction regions that are relatively upstream and downstream. In this embodiment, the following combinations are included. A combination of the relatively upstream and downstream suction areas is referred to as a first suction area (upstream side) and a second suction area (downstream side).
(A1) Upstream side: suction area E11, downstream side: suction area E12
(A2) Upstream side: suction area E11, downstream side: suction area E13
(A3) Upstream side: suction area E11, downstream side: suction area E14
(A4) Upstream side: suction area E11, downstream side: suction area E15
(A5) Upstream side: suction area E12, downstream side: suction area E13
(A6) Upstream side: suction area E12, downstream side: suction area E14
(A7) Upstream side: suction area E12, downstream side: suction area E15
(A8) Upstream side: suction area E13, downstream side: suction area E14
(A9) Upstream side: suction area E13, downstream side: suction area E15
(A10) Upstream side: suction area E14, downstream side: suction area E15

In the present embodiment, relative to the upstream and downstream suction regions (first suction region and second suction region) corresponding to the combination of the spinning nozzles that are relatively upstream and downstream, It is preferable to control the suction force according to the deposition state of the fibers on the collecting surface 212S. The combination of the spinning nozzles L located relatively upstream and downstream is called the first spinning nozzle (upstream side) and the second spinning nozzle (downstream side). That is, the suction force of the first suction region corresponding to the first spinning nozzle on the upstream side in the MD direction is made different from the suction force of the second suction region corresponding to the second spinning nozzle on the downstream side. As a result, the temperature of the spinning space can be suitably maintained by controlling the intake amount of outside air accompanying suction within a desired range, and the fibers discharged from the spinning nozzle L can be formed with a desired fiber diameter. In addition, the amount of suction on the downstream side is increased in accordance with the accumulation of fibers to suppress scattering of the fibers, and a nonwoven fabric having a desired basis weight can be produced favorably.
Such a combination (first spinning nozzle and first suction area and second spinning nozzle and second suction area) includes suction areas E11, E12, E14 and E15 corresponding to spinning nozzles L1 to L4. A combination is mentioned.
(B1) Upstream side: spinning nozzle L1 and suction area E11, downstream side: spinning nozzle L2 and suction area E12
(B2) Upstream side: spinning nozzle L1 and suction area E11, downstream side: spinning nozzle L3 and suction area E14
(B3) Upstream side: spinning nozzle L1 and suction area E11, downstream side: spinning nozzle L4 and suction area E15
(B4) Upstream side: spinning nozzle L2 and suction area E12, downstream side: spinning nozzle L3 and suction area E14
(B5) Upstream side: spinning nozzle L2 and suction area E12, downstream side: spinning nozzle L4 and suction area E15
(B6) Upstream side: spinning nozzle L3 and suction area E14, downstream side: spinning nozzle L4 and suction area E15

Next, the spinning process and the collecting process performed using the above-described manufacturing apparatus 100 in the nonwoven fabric manufacturing method of the present embodiment will be described.

A spinning nozzle L supplied with a molten polymer from an extruder 11 through a gear pump 12 discharges the molten polymer toward a corresponding suction area E and draws to form fibers. The spinning process for forming this fiber is performed in parallel for each of the suction areas E11 to E15, as illustrated in FIG. The formed fibers are sucked by the suction forces of the suction regions E11 to E15 arranged from the upstream side in the MD direction and collected on the collecting surface 212S. Along with the downstream movement of the collection surface 212S, the fibers discharged from the downstream spinning nozzle move to the downstream suction region E with respect to the fibers collected on the collection surface 212S in the upstream suction region E. , further deposits on the collecting surface 212S. Due to the difference in the accumulated amount of fibers, the spinning space between the spinning nozzle L and the collection surface 212S is likely to have a difference in the suction force exerted from the suction region E between the upstream side and the downstream side. be placed.

In the nonwoven fabric manufacturing method of the present embodiment, the suction force of the suction region E is controlled in accordance with the change in the deposited amount of fibers. That is, among the plurality of suction regions, the suction region on the upstream side is controlled so as to make the suction force of the fibers smaller than that on the downstream side. For example, among the suction regions E11 to E15, in the combination of the first suction region and the second suction region in each of (A1) to (A10) described above, the suction force of the first suction region is changed to the suction force of the second suction region. controlled to be smaller than Among them, in each combination of (B1) to (B6) described above, the fibers discharged from the first spinning nozzle are collected in the first suction region with a lower suction force than in the second suction region, and the second spinning nozzle Preferably, the fibers discharged from the second suction area are collected with a greater suction force than in the first suction area. This control is performed by the aforementioned suction force control mechanism provided in the collecting device 20 .
As a result, in the spinning space between the spinning nozzle L and the collecting surface 212S, the intake amount of outside air accompanying suction at the position of the suction region on the upstream side can be suppressed more than the position of the suction region on the downstream side. can. By suppressing the intake of outside air, it is possible to suppress the decrease in the temperature of the spinning space on the upstream side. As a result, the temperature of the spinning space on the upstream side is maintained within a desired range, the drawing ability is maintained when the molten polymer is expelled from the spinning nozzle to form fibers, and the increase in fiber diameter is suppressed. . As a result, fibers with a desired fiber diameter can be collected on the collection surface 212S.
In addition, in the suction area on the downstream side, as described above, the amount of fibers deposited on the collecting surface 212S is relatively larger than that on the upstream side. On the other hand, in the present embodiment, in the suction area on the downstream side where the amount of deposited fibers is relatively increased, suction is performed with a relatively larger suction force than in the suction area on the upstream side. As a result, reduction in the action of the suction force in the suction region E via the collecting surface 212S is suppressed, and good suction force can be applied to the spun fibers, thereby suppressing scattering of the fibers. As a result, a nonwoven fabric having a desired basis weight can be produced on the collecting surface 212S with a favorable yield.

In the combinations of the suction areas in (A1) to (A10) and (B1) to (B6) above, the suction area (second 2 suction area) to the suction force (suction air volume) is preferably 0.9 or less, more preferably 0.83 or less, and even more preferably 0.75 or less, from the viewpoint of further enhancing the above effects. In addition, from the viewpoint of facilitating suppression of fiber scattering, the ratio of the suction forces (suction air volume) is preferably 0.1 or more, more preferably 0.5 or more, and even more preferably 0.6 or more.

Regarding such control of the suction force, in the suction region corresponding to the spinning nozzle, a combination of a first suction region on the upstream side with a relatively small suction force and a second suction region on the downstream side with a relatively large suction force. is preferably at least one set. That is, it is preferable to have at least one combination of the above (B1) to (B6). Among them, it is more preferable to perform control so as to minimize the suction force of the suction region E11 located on the most upstream side. In that case, the suction forces of the suction regions E12, E14 and E15 may be in random order from the upstream side to the downstream side. However, from the viewpoint of making the effect of the above control of the suction force more effective, it is further preferable to control the suction force so as to gradually decrease from the downstream side to the upstream side (E11<E12<E14<E15). preferable. That is, among the suction regions E11, E12, E14 and E15 for sucking the fibers discharged from the spinning nozzle L, the suction region E15 for sucking and collecting the fibers discharged from the spinning nozzle L4 has the largest suction force, The suction force of the suction region E14 that sucks and collects the fibers discharged from the spinning nozzle L3 is the second largest, and the suction force of the suction region E12 that sucks and collects the fibers discharged from the spinning nozzle L2 is three. It is preferable to control the suction force of the suction region E11, which is the second largest and sucks and collects the fibers discharged from the spinning nozzle L1, to be the smallest.
At this time, the suction force is preferably E12≦E13≦E14 in the suction region E13 not corresponding to the spinning nozzle. As a result, it is expected that the temperature in the spinning space can be uniformly controlled, and the fiber diameter of the spun fibers and the basis weight of the nonwoven fabric will be uniform.

Furthermore, in the method for manufacturing the nonwoven fabric of the present embodiment, it is preferable that the CD direction orthogonal to the MD direction includes a region that increases the attracting force of the fibers on the inner side rather than on the outer side.
Specifically, in the plurality of suction sections 213 shown in FIG. 3, suction regions E21 to E26 are formed as illustrated in FIG. Here, among the plurality of partition plates B of the suction section 213, each of the plurality of partition plates B2 extending in the CD direction is provided with a plurality of communicating portions 215. As shown in FIG. Thereby, each of the plurality of suction sections 213 forming the suction regions E21 to E26 communicates with each other in the MD direction.
Each of the suction areas E21 to E26 extends along the MD direction and is arranged adjacent to each other in the CD direction. The suction area E21 and the suction area E26 are provided outside the suction area E22 and the suction area E23, and the suction areas E22 to E25 are provided inside the suction area E21 and the suction area E26.

In the embodiment illustrated in FIG. 4, the suction region E21 and the suction region E26 mainly include blank portions of the manufactured nonwoven fabric and correspond to portions of which the desired basis weight is not reached. That is, in the suction regions E21 and E26, the amount of fibers deposited on the collecting surface 212S is smaller than in the suction regions E22 to E25 inside them. Therefore, the suction force of the suction regions E22 to E25 inside the suction regions E21 and E26 outside in the CD direction is increased. In this case, the suction blower 221 is preferably connected to the suction sections 213 at both ends in the MD direction of each of the suction regions E21 to E26.
This suction force can be controlled by the suction force control mechanism described above. In the case of the suction control mechanism of the second aspect described above, control is performed as follows.
That is, the size (opening area) of the opening region 215a of the communication hole 215 provided in the partition plate B2 that partitions the suction sections 213 constituting the suction regions E21 to E26 is determined from the suction region E21 and the suction region E26. is also increased in the suction regions E22 to E25. As a result, the suction force with which the suction area E21 and the suction area E26 are sucked by the suction blower 221 becomes smaller than the suction force with which the suction areas E22 to E25 are sucked by the suction blower 221. FIG.
Due to this suction force control in the CD direction, the intake amount of outside air at the positions of the suction regions E21 and E26 can be suppressed more than at the positions of the suction regions E22 to E25. Thereby, the temperature of the spinning space corresponding to the suction areas E21 and E26 on the outside in the CD direction is kept within a desired range. As a result, in combination with the aforementioned control of the suction forces E11 to E15 arranged in the MD direction, the increase in fiber diameter is suppressed in a wider spinning space. Moreover, scattering of fibers is suppressed not only on the downstream side in the MD direction but also on the inner side in the CD direction. As a result, it is possible to produce a nonwoven fabric having a desired basis weight on the collecting surface 212S more preferably with a high yield. The control of the suction force in the CD direction may be performed in part or all of the suction sections 213 in the MD direction in the suction regions E21 to E25. Also, the amount of suction in the CD direction may be controlled differently in the MD direction according to the amount of fiber deposition. For example, the above-described suction force in the CD direction may be controlled in some of the suction areas E11 to E15 arranged in the MD direction shown in FIG. may have different degrees of control over the suction force. When simultaneously controlling the suction forces of the suction areas E11 to E15 and the suction areas E21 to E26, suction sections are set for each of the MD direction and the CD direction.
In the form illustrated in FIG. 2, suction sections (opening regions 215a shown in FIG. 3) at both ends (outer sides) of each of the suction regions E11 to E15 are set so that the suction force becomes smaller on the upstream side, and each suction region The size (opening area) of the opening region 215a of the communication hole 215 provided in the partition plate B2 that partitions the suction sections 213 constituting E21 to E26 is larger than the suction region E21 and the suction region E26. ~ E25 is set to increase.

The nonwoven fabric manufacturing method and manufacturing apparatus of the present embodiment can be applied to various direct-spinning nonwoven fabric manufacturing methods. Examples thereof include an electrospinning method, a spunbond method, a spunmelt method, a meltblown method, and the like. Depending on each type, other steps may be included in addition to the spinning and collection steps described above. For example, an embossing process may be applied to a collection of fibers deposited on the collection surface 212S.

Among them, the nonwoven fabric manufacturing method and manufacturing apparatus of the present embodiment are preferably applied to the electrospinning method.
In the electrospinning method, a solution or melt of a resin having fiber-forming ability is charged and discharged into an electric field, and the discharged liquid is stretched by the electric field to form fibers, and the fibers are deposited on the collection surface 212S. A fine fiber layer can be formed by allowing the Specifically, a positive high voltage is applied to the spinning nozzle L side. The power supply 30 shown in FIG. 1 is, for example, a DC high-voltage power supply with a positive electrode output of about 10 to 30 kV. On the other hand, the collection surface 212S is made negatively charged. As a result, an electric field is applied to the molten polymer in the spinning nozzle L to eject it. The molten polymer ejected by the action of the electric field is stretched toward the negative charge collection surface 212S to form ultrafine fibers. The ultra-fine fibers are collected on the collection surface 212S by the suction force in the suction area E described above and deposited. As a result, the nonwoven fabric is formed in the state in which the ultrafine fibers are deposited as they are.

In the electrospinning method, the extruded resin solution or melt is stretched by the Coulomb force in the electric field, thereby obtaining nanometer-order ultrafine fibers that cannot be achieved by conventional stretching using air or the like. . By electrospinning, it is possible to produce a non-woven fabric of extremely fine fibers on the order of nanometers, which cannot be obtained by conventional production methods (eg, meltblown method).
Further, in the electrospinning method, since the fibers are drawn by electric drawing, long fibers are formed without breaking the fibers, as compared with the drawing by blowing hot gas in the meltblown method, for example. In addition, the ejected solution is stretched by the coulomb force in the electric field, and the solvent instantly evaporates, forming nanofibers while solidifying the raw material. Therefore, in the nonwoven fabric obtained by the electrospinning method, the long fibers are often not fused together, and the density is moderately suppressed because the fibers are entangled with each other, and the movement of the fibers is not hindered. Provides flexibility. Thus, the nonwoven fabric obtained by the electrospinning method tends to be relatively bulky unlike, for example, a meltblown nonwoven fabric in fiber state, and is further rich in flexibility.

In the nonwoven fabric manufacturing method and manufacturing apparatus of the present embodiment, when the electrospinning method is applied, the average fiber diameter of the nonwoven fabric obtained can be 0.2 μm or more and 5 μm or less.

In this way, since the fibers discharged from the spinning nozzle L by the electrospinning method are extremely fine on the order of nanometers, scattering tends to occur in the process of depositing the fibers on the collecting surface 212S in the conventional art. . On the other hand, in the nonwoven fabric manufacturing method and manufacturing apparatus of the present embodiment, since the suction force on the downstream side in the MD direction or the suction force on the inner side in the CD direction is increased in addition to this, the deposition of fibers The effect of suppressing scattering of fibers in the process is enhanced. As a result, it is possible to produce a nonwoven fabric with a fine grain and high flexibility obtained by spinning ultrafine fibers with a desired basis weight at a high yield.

10 spinning device 14 spinning device 20 collecting device 21 belt conveyor 22 suction power section 100 manufacturing device 141 first spinning device 142 second spinning device 143 third spinning device 144 fourth spinning device 211 conveyor roll 212 belt 212S collection surface 213 suction section 215 communication hole,
215a hole area 221 suction blower B, B1, B2 partition plate E, E11 to E15, E21 to E26 suction area L, L1 to L4 nozzle

Claims (8)

A spinning step of discharging a molten thermoplastic resin from a spinning nozzle to form fibers, sucking the fibers in a plurality of suction regions arranged from the upstream side in the machine flow direction and collecting them on a collecting surface, and depositing the fibers while moving downstream of the collecting surface;
The method of manufacturing a nonwoven fabric, wherein the plurality of suction regions includes an upstream suction region that is controlled to have a smaller suction force on the fibers than on a downstream side. The spinning nozzle has a first spinning nozzle on the upstream side and a second spinning nozzle on the downstream side of the first spinning nozzle,
The plurality of suction areas have a first suction area corresponding to the first spinning nozzle and a second suction area corresponding to the second spinning nozzle,
In the collecting step, the fibers discharged from the first spinning nozzle are collected in the first suction area with a suction force smaller than that in the second suction area, and the fibers discharged from the second spinning nozzle are 2. The method for producing a nonwoven fabric according to claim 1, wherein the particles are collected in the second suction area with a greater suction force than in the first suction area. 3. The method for manufacturing a nonwoven fabric according to claim 1, wherein said suction region includes a region in which the suction force of said fibers is greater on the inner side than on the outer side in the direction orthogonal to the machine flow direction. The method for producing a nonwoven fabric according to any one of claims 1 to 3, wherein the spinning step uses an electrospinning method. The method for producing a nonwoven fabric according to any one of claims 1 to 4, wherein the nonwoven fabric obtained has an average fiber diameter of 0.2 µm or more and 5 µm or less. a spinning device having a plurality of spinning nozzles for discharging molten thermoplastic resin;
a collection device that sucks the fibers discharged from the plurality of spinning nozzles, collects them on a collection surface, and deposits the fibers as the collection surface moves downstream;
The plurality of spinning nozzles includes a first spinning nozzle provided upstream and a second spinning nozzle provided downstream of the first spinning nozzle,
The collection device has a plurality of suction regions including a first suction region corresponding to the first spinning nozzle and a second suction region corresponding to the second spinning nozzle, and the first suction region An apparatus for manufacturing a nonwoven fabric, comprising a suction force control mechanism that makes the suction force different from the suction force of the second suction area. 7. The nonwoven fabric manufacturing apparatus according to claim 6, wherein said collection device has a communication hole that communicates the suction space of said absorption area. 8. The apparatus for manufacturing a nonwoven fabric according to claim 7, wherein said communicating hole has a mechanism for varying an opening area.

Images