Nonwoven fabric manufacturing method and nonwoven fabric manufacturing device

Abstract

To provide a technique capable of suppressing the occurrence of width shrinkage in a nonwoven fabric.SOLUTION: A nonwoven fabric is composed of a plurality of fiber layers containing a first fiber layer which is made of a crimpable fiber having a crimp number of 15 pcs. / 25 mm or more, and a second fiber layer which is made of a fiber having a fiber diameter of 2 to 100 denier and is in a state where the fibers are oriented in an MD direction.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention , non The present invention relates to a method for producing a woven fabric and an apparatus for producing a nonwoven fabric. [Background technology]

[0002] Conventionally, composite fibers for forming nonwoven fabrics have been known (for example, Patent Document 1). The composite fibers described in Patent Document 1 have crimping properties in order to provide bulky nonwoven fabrics. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2017-222972 A Summary of the Invention [Problem to be solved by the invention]

[0004] A nonwoven fabric having a crimping property has high elasticity because the fibers are looped. When a highly elastic nonwoven fabric is used as a material for absorbent articles, masks, etc., the nonwoven fabric stretches in the MD direction when pulled in the MD direction inside a processing machine during the manufacturing process, resulting in width shrinkage. Since the width of a nonwoven fabric is set according to the dimensions of the finished product, it is not desirable for the nonwoven fabric to shrink in width. In addition, in order to achieve stable operation, it is possible to adjust the width of the nonwoven fabric when it is fully stretched in the MD direction to the dimensions of the finished product, taking into account the occurrence of width shrinkage in the nonwoven fabric, but the fully stretched nonwoven fabric will lose bulk.

[0005] An object of the present invention is to provide a technique capable of suppressing the occurrence of width shrinkage in nonwoven fabrics. [Means for solving the problem]

[0006] In order to solve the above problems, the present invention provides a first fiber layer made of crimped fibers and a second fiber layer in which fibers are oriented in the MD direction.

[0007] In detail, the present invention relates to a nonwoven fabric composed of multiple fiber layers, comprising a first fiber layer composed of crimpable fibers having a crimp number of 15 or more per 25 mm, and a second fiber layer having a fiber diameter of 2 to 100 denier and fibers oriented in the MD direction.

[0008] In the nonwoven fabric, the first fiber layer may have a MD elongation at break of 50% or more.

[0009] In the nonwoven fabric, the first fiber layer, the second fiber layer, and the first fiber layer may be laminated in this order.

[0010] The present invention can also be seen as a method for producing a nonwoven fabric. For example, the present invention may be a method for producing a nonwoven fabric composed of a plurality of fiber layers, which may include a step of forming a first fiber layer composed of crimpable fibers having a crimp number of 15 or more per 25 mm, and a step of forming a second fiber layer having a fiber diameter of 2 to 100 denier and fibers oriented in the MD direction.

[0011] The present invention can also be seen as an aspect of a nonwoven fabric manufacturing apparatus. For example, the present invention provides a nonwoven fabric manufacturing apparatus including a fiber spraying device that sprays fibers, and a sheet conveying device that collects the fiber bundles sprayed from the fiber spraying device on a conveying surface, forms the nonwoven fabric into a sheet, and conveys the nonwoven fabric in a conveying direction. The nonwoven fabric manufacturing apparatus may be configured to produce a nonwoven fabric composed of a plurality of fiber layers, and the fiber spraying device may include a first fiber spraying device that sprays filaments in a bundle to form a first fiber layer composed of crimpable fibers having a crimp number of 15 or more per 25 mm, and a second fiber spraying device that sprays filaments in a bundle to form a second fiber layer having a fiber diameter of 2 to 100 denier and fibers oriented in the MD direction. Effect of the Invention

[0012] According to the present invention, the occurrence of width shrinkage in the nonwoven fabric can be suppressed. [Brief description of the drawings]

[0013] [Figure 1] FIG. 1 is a plan view of a nonwoven fabric according to an embodiment. [Diagram 2] FIG. 2 is a cross-sectional view in the CD direction of the nonwoven fabric according to the embodiment. [Diagram 3] FIG. 3 is a diagram showing a nonwoven fabric manufacturing apparatus for manufacturing the nonwoven fabric according to the embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the configurations of the following embodiments are merely examples, and the present invention is not limited to the configurations of these embodiments.

[0015] <Embodiment> Fig. 1 is a plan view of nonwoven fabric C according to this embodiment as viewed from above. Fig. 2 is a cross-sectional view in the CD direction of nonwoven fabric C cut along line AA shown in Fig. 1. Nonwoven fabric C is a sheet with the longitudinal direction in the MD direction, and is composed of multiple layers.

[0016] As shown in Fig. 2, the nonwoven fabric C has a layered structure in which fiber layers are laminated in the order of a crimped fiber layer C1 (an example of the "first fiber layer" in the present application), a spunbond fiber layer C2 (an example of the "second fiber layer" in the present application), and a crimped fiber layer C1 from the bottom. The crimped fiber layer C1 is a fiber layer composed of crimpable fibers, and is formed to be bulky because the fibers are looped. The spunbond fiber layer C2 has fibers oriented in the MD direction (machine direction), and is formed thinner than the crimped fiber layer C1. The nonwoven fabric C according to this embodiment has bulky crimped fiber layers C1 on both the top and bottom sides, which improves the feel when used in absorbent articles, masks, etc.

[0017] The degree of crimping of the fibers in the crimped fiber layer C1 can be indicated by the number of crimps of the fibers measured in accordance with, for example, Japanese Industrial Standard JIS L1015. The number of crimps in the crimped fiber layer C1 in this embodiment is 15 / 25 mm. The crimped fiber layer C1 also has a breaking elongation in the MD direction of 50% or more.

[0018] In the spunbond fiber layer C2, the fiber diameter is 2 to 100 denier (2 denier or more and 100 denier or less). Note that this fiber diameter is a value when the line speed is 23 to 1125 m / min in the spunbond manufacturing method described later. In addition, in the spunbond fiber layer C2, the number density in the CD direction is 2 to 8 fibers / mm.

[0019] In the nonwoven fabric C, each fiber layer is compressed and bonded to each other by embossing. The embossed area ratio is 5 to 25%. The basis weight of each fiber layer is 10 to 30 g / m 2 Such nonwoven fabric C is suitable as a material for absorbent articles and masks.

[0020] The nonwoven fabric C according to this embodiment has a spunbond fiber layer C2, which suppresses stretching in the MD direction. This suppresses stretching in the MD direction of the nonwoven fabric C even when the nonwoven fabric C is pulled in the MD direction inside the processing machine. Therefore, the nonwoven fabric C according to this embodiment can suppress the occurrence of width shrinkage. Such a nonwoven fabric C has a high bulkiness and is made of a material. When used, stable operation can be achieved.

[0021] Next, a manufacturing method and manufacturing device for the nonwoven fabric C according to this embodiment will be described with reference to Fig. 3. Fig. 3 is a diagram showing a nonwoven fabric manufacturing device M for manufacturing the nonwoven fabric C according to this embodiment. In Fig. 3, the nonwoven fabric manufacturing device M includes three ejection devices (fiber ejection devices) 10, and each of the ejection devices 10 (10A, 10B, 10C) includes a spinning device 20, a cold air device 30, and an injector 40. The ejection devices 10A and 10C are an example of a "first fiber ejection device" for forming the crimped fiber layer C1, and the ejection device 10B is an example of a "second fiber ejection device" for forming the spunbond fiber layer C2.

[0022] In the nonwoven fabric manufacturing apparatus M, together with the ejection device 10, a collecting conveyor (sheet transport device) 50, an embossing device 60, and a winder 70 are arranged in series so that various processes can be performed. The ejection devices 10A, 10B, and 10C are arranged in series in the transport direction relative to the transport surface above the collecting conveyor 50. The nonwoven fabric manufacturing apparatus M is constructed to continuously manufacture a nonwoven fabric C whose CD direction (width direction) is the direction toward the paper surface of FIG. 3, and manufactures the nonwoven fabric C by a so-called spunbond method in which spun fibers (filaments) are collected in a sheet shape and embossed to appropriately bond the fibers together.

[0023] The spinning device 20 is configured to include an extruder 21 and a spinneret 23. The extruder 21 melts raw material resin R (R1, R2, R3) supplied to a hopper 22, and sends a predetermined flow rate of the melt to the spinneret 23 by the rotation of a spiral rotor 21r. The spinneret 23 has a plurality of composite spinning nozzles (not shown) configured to discharge the melt while forming a desired fibrous structure, and spins (discharges) the melt from the extruder 21 in the direction of gravity as a bundle F of a plurality of filaments (fibers) f (hereinafter referred to as a "filament aggregate").

[0024] Here, the raw material resin R may be multi-layered by stacking sheet-like filaments of the same materials R1, R2, R3 without changing the type for each of the ejection devices 10A, 10B, 10C, or may be multi-layered by stacking sheet-like filaments of different materials R1, R2, R3 by changing the type for each of the ejection devices 10A, 10B, 10C. For example, the raw material resin R is mainly composed of thermoplastic resin, and may be the same or different polyolefin resins such as polypropylene (PP) and polyethylene (PE), and may contain additives such as various stabilizers such as known heat stabilizers and weather stabilizers, antistatic agents, slip agents, antiblocking agents, antifogging agents, lubricants, dyes, pigments, natural oils, synthetic oils, waxes, etc., as appropriate.

[0025] The cold air device 30 is equipped with a pair of open-type blowers 31, 32 arranged at opposing positions. This cold air device 30 cools the filament aggregate F, which is discharged from the spinning device 20 and passes from above to below, by blowing cooling air Ac from each of the blowers 31, 32. Here, the cold air device 30 is installed such that one blower 31 is a large type that can be used as a main blower, and the other blower 32 facing it is a small type that can be used as a sub blower for auxiliary use.

[0026] The injector 40 has a structure that blows downward high-pressure air as a driving fluid onto the filament assembly F that descends through the body 41 from above in the spinning direction, thereby generating a low-pressure region on the inlet side of the body 41. The injector 40 draws the descending filament assembly F so as to draw it into the low-pressure region on the inlet side of the body 41, while also drawing it downward within the body 41 with the high-pressure air, thereby stretching the filament assembly F that descends from above in the spinning direction from above downward via the cooling air device 30.

[0027] The collecting conveyor 50 is constructed with a main conveyor 51, sub-conveyors 52 and 53, and a suction box (suction means) 54. The main conveyor 51 is installed so that a mesh-like collecting belt 151 formed wider than the width of the filament aggregate F and breathable on both sides is wound around a group of rollers 151r and driven to rotate. The sub-conveyors 52 and 53 are also installed so that mesh-like collecting belts 152 and 153 formed wider than the width of the filament aggregate F and breathable on both sides are wound around a group of rollers 152r and a group of rollers 153r, respectively, and driven to rotate in opposite directions.

[0028] The collecting belt 151 is wound around a group of rollers 151r with a length such that the upper surface 151a is reliably positioned at the spraying points below the ejection devices 10A, 10B, and 10C, and is adapted to receive and transport the filament aggregate Fa pulled down by the injector 40, thereby collecting the filament aggregate Fa in a cloth (sheet) form. That is, the collecting belt 151 has a sufficient area to collect the sheet-like filament aggregate Fa and functions as a collecting surface and a transport surface by rotating from the upstream end (leading end) to the downstream end (rear end) in the rotating movement direction (transport direction) of the upper surface 151a. The filament aggregate Fa becomes the lower crimped fiber layer C1 in the nonwoven fabric C.

[0029] The collecting belt 152 is wound around a group of rollers 152r with its upper surface 152a positioned at a spraying point below the ejection device 10B located at the middle of the rotational movement direction of the upper surface 151a of the collecting belt 151, and is adapted to collect the filament aggregate Fb in a sheet-like form by receiving and transporting it as it is pulled down by the injector 40. The collecting belt 153 is wound around a group of rollers 153r with its upper surface 153a positioned at a spraying point below the ejection device 10C located at the downstream end (rear end) of the rotational movement direction of the upper surface 151a of the collecting belt 151, and is adapted to collect the filament aggregate Fc in a sheet-like form by receiving and transporting it as it is pulled down by the injector 40. The filament aggregate Fb becomes the spunbond fiber layer C2 in the nonwoven fabric C.

[0030] These collecting belts 152, 153 are installed at a position downstream from below the ejection device 10A located at the upstream end (leading end) in the circulating direction of the upper surface 151a of the collecting belt 151, and are positioned between the upper surface 151a and the ejection devices 10B, 10C and driven to rotate in the reverse direction, so that the upper surfaces 152a, 153a function as a collecting surface and a conveying surface for collecting the sheet-like filament assemblies Fb, Fc. These collecting belts 152, 153 are driven to rotate so as to sandwich the sheet-like filament assemblies Fb, Fc between their lower parts facing the upper surface (upper part) 151a of the collecting belt 151 without peeling off and turning over, and function to assist in conveying them downstream.

[0031] The suction box 54 is housed in the collecting belt 151 of the main conveyor 51 and is partitioned into suction chambers 154a, 154a-2, 154b, 154b-2, 154c, and 154c-2, each of which functions as a decompression chamber. Suction ports (not shown) are arranged in the suction chambers 154a to 154c-2 so as to suck the upper side, and suction fans 155a to 155c-2, which can be driven individually, are connected to the suction chambers 154a to 154c-2 so as to be capable of sucking the upper side.

[0032] The suction chambers 154a, 154b, and 154c are installed so as to be located below the injectors 40 of the ejection devices 10A, 10B, and 10C, respectively, and the suction chambers 154a-2, 154b-2, and 154c-2 are installed so as to be located downstream of these suction chambers 154a, 154b, and 154c.

[0033] The suction chamber 154a is installed so as to be located directly below the collection belt 151 of the main conveyor 51 below the injector 40 of the ejection device 10A, and the suction fan 155a is driven to reduce pressure, thereby sucking in the area from directly below the collection belt 151 upward.

[0034] The suction chamber 154a-2 is installed adjacent to the downstream side of the suction chamber 154a so as to be located directly below the collection belt 151 of the main conveyor 51 between it and the suction chamber 154b located below the ejection device 10B, as described below. The suction fan 155a-2 is driven to reduce pressure and suck in the area above the collection belt 151.

[0035] As a result, the filament aggregate Fa spun by the ejection device 10A is sucked by the suction chamber 154a below the collecting belt 151 of the main conveyor 51 so as to be collected on the upper surface 151a. Therefore, the filament aggregate Fa is collected in a sheet-like shape on the upper surface 151a and held and transferred as the collecting belt 151 moves around in the length direction. Thereafter, the filament aggregate Fa is transferred from the suction chamber 154a to the adjacent suction chamber 154a-2 as the collecting belt 151 moves around in the length direction, and is sucked and held so as to maintain the sheet-like shape and transferred.

[0036] The suction chamber 154b is installed so as to be located directly below the collecting belt 151 of the main conveyor 51 below the injector 40 of the ejection device 10B, and when the suction fan 155b is driven to reduce pressure, it sucks in the area directly below the collecting belt 151 and above the collecting belt 152 of the sub-conveyor 52.

[0037] The suction chamber 154b-2 is installed adjacent to the downstream side of the suction chamber 154b so as to be located directly below the collection belt 151 of the main conveyor 51 between it and the suction chamber 154c located below the ejection device 10C, as described below. The suction fan 155b-2 is driven to reduce pressure and suck in the area from directly below the collection belt 151 upward.

[0038] As a result, the filament aggregate Fa spun by the ejection device 10A is sucked and held in sheet form on the upper surface 151a by the suction chambers 154b and 154b-2 below the collecting belt 151 of the main conveyor 51, following the above-mentioned suction chambers 154a and 154a-2, and transported thereon.

[0039] Further, the filament aggregate Fb spun by the ejection device 10B is sucked by the suction chamber 154b below the collecting belt 151 of the main conveyor 51 so as to be collected on the upper surface 152a of the collecting belt 152 of the sub-conveyor 52 on the upper surface 151a. Therefore, the filament aggregate Fb is collected and held in a sheet-like shape on the upper surface 152a as the collecting belt 152 moves around in the length direction, and is transported.

[0040] Incidentally, the collecting belt 152 of the sub-conveyor 52 rotates in the opposite direction to the collecting belt 151 of the main conveyor 51, so that the upper surface 152a of the collecting belt 152 moves in the opposite direction, and then is turned upside down and moves in the same direction facing the upper surface 151a of the collecting belt 151 of the main conveyor 51. Therefore, the filament aggregate Fb spun by the ejection device 10B is collected and held in a sheet-like shape on the upper surface 152a of the collecting belt 152 of the sub-conveyor 52 and transferred, and then overlaps the sheet-like filament aggregate Fa on the upper surface 151a of the collecting belt 151 of the main conveyor 51, and is sucked and held in the sheet-like shape by the suction chamber 154b below the collecting belt 151 of the main conveyor 51 and transferred.

[0041] As a result, the filament aggregate Fab (Fa, Fb) that is collected, held, and stacked in a sheet shape below the ejection device 10B is transferred from the suction chamber 154b to the adjacent suction chamber 154b-2 as the collection belt 151 moves around in the longitudinal direction, and is transported while being suctioned and held so as to maintain the sheet shape.

[0042] The suction chamber 154c is installed so as to be located directly below the collecting belt 151 of the main conveyor 51 below the injector 40 of the ejection device 10C, and when the suction fan 155c is driven to reduce pressure, it sucks in the area directly below the collecting belt 151 and above the collecting belt 153 of the sub-conveyor 53.

[0043] The suction chamber 154c-2 is installed adjacent to the downstream side of the suction chamber 154c and is located immediately below the end of the collection belt 151 of the main conveyor 51, as described below. The suction fan 155c-2 is driven to reduce pressure and suck in the area from directly below the collection belt 151 upward.

[0044] As a result, the filament aggregates Fab spun by the ejection devices 10A and 10B are transported, following the above-mentioned suction chambers 154a to 154b-2, by the suction chambers 154c and 154c-2 below the collecting belt 151 of the main conveyor 51, while remaining in a sheet-like form overlapping on the upper surface 151a.

[0045] The filament aggregate Fc spun by the ejection device 10C is sucked by the suction chamber 154c below the collecting belt 151 of the main conveyor 51 so as to be collected on the upper surface 153a of the collecting belt 153 of the sub-conveyor 53 on the upper surface 151a. Therefore, the filament aggregate Fc is collected in a sheet-like form on the upper surface 153a and held and transported as the collecting belt 153 moves around in the length direction. The filament aggregate Fc becomes the upper crimped fiber layer C1 in the nonwoven fabric C.

[0046] Incidentally, the collecting belt 153 of the sub-conveyor 53 also rotates in the opposite direction to the collecting belt 151 of the main conveyor 51, so that the upper surface 153a of the collecting belt 153 moves in the opposite direction, and then is turned upside down and moves in the same direction facing the upper surface 151a of the collecting belt 151 of the main conveyor 51. Therefore, the filament aggregate Fc spun by the ejection device 10C is collected and held in a sheet-like form on the upper surface 153a of the collecting belt 153 of the sub-conveyor 53 and transferred, and then is further overlapped with the sheet-like filament aggregate Fab on the upper surface 151a of the collecting belt 151 of the main conveyor 51, and is sucked and held in the sheet-like form by the suction chamber 154c below the collecting belt 151 of the main conveyor 51 and transferred.

[0047] As a result, the filament aggregate Fabc (Fa, Fb, Fc) that is collected, held, and stacked in a sheet shape below the ejection device 10C is transferred from the suction chamber 154c to the adjacent suction chamber 154c-2 as the collection belt 151 moves around in the longitudinal direction, and is transported while being suctioned and held so as to maintain the sheet shape.

[0048] In short, the collecting conveyor 50 collects and holds the filament assemblies Fa, Fb, Fc spun by the spraying devices 10A, 10B, 10C on the upper surfaces 151a-153a of the collecting belts 151-153 by suction in a sheet-like shape of a predetermined thickness using suction boxes 54, and then stacks them to form a filament assembly Fabc (nonwoven fabric C) before embossing, which is then transported downstream to the embossing device 60.

[0049] The embossing device 60 includes a pair of embossing rolls 61, 62, which rotate relative to each other with their cylindrical outer circumferential surfaces 61a, 62a in pressure contact with each other. In the embossing device 60, embossing protrusions (not shown) arranged regularly or irregularly on the cylindrical outer circumferential surface 62a of the upper embossing roll 62 are pressed against the smooth cylindrical outer circumferential surface 61a of the lower embossing roll 61 with a desired pressure.

[0050] As a result, the embossing device 60 is configured to sandwich the filler between the embossing rolls 61 and 62. The ment assembly Fabc is fed in the relative rotation direction, and is embossed at a plurality of embossing locations corresponding to the positions where the embossing protrusions are formed, whereby the filaments f are entangled and squeeze-bonded together, to form a nonwoven fabric C that maintains its sheet-like shape. The embossed protrusions formed on the cylindrical outer circumferential surface 62a of the embossing roll 62 may be formed on the cylindrical outer circumferential surface 61a of the embossing roll 61, or may be formed on both of these cylindrical outer circumferential surfaces 61a, 62a, and further may be formed in a concave shape rather than a convex shape, and may be squeeze-bonded by pressing, for example, a continuous rib shape against the opposing cylindrical surface.

[0051] The winder 70 receives the nonwoven fabric C in which the filaments f of the filament aggregate Fabc are intertwined and bonded by the embossing device 60 while adjusting the tension so as not to cause slack, and continuously winds the nonwoven fabric C into a roll without wrinkles and with the desired winding hardness.

[0052] This allows the winder 70 to prepare the nonwoven fabric C of a desired length, in which the filament aggregate Fabc is formed into a sheet and wound into a roll, so that it can be supplied to the next processing step or the like.

[0053] As described above, the collecting conveyor 50 of this embodiment is arranged such that the suction chambers 154a to 154c-2 of the suction box 54 installed under the collecting belt 151 of the main conveyor 51 correspond to the injectors 40 of the ejection devices 10A to 10C, and the suction fans 155a to 155c-2 connected to each of them are set to suck at a wind speed (air volume) according to the partitioned range (area) of the suction chambers 154a to 154c-2 and the required suction pressure. Here, the partitioned range and suction pressure of the suction chambers 154a to 154c-2 may be set appropriately.

[0054] Specifically, the suction chamber 154a, without the use of a sub-conveyor, sucks in the filament aggregate Fa that is pulled down from the outlet of the injector 40 of the ejection device 10A directly above the collecting belt 151 of the main conveyor 51 from below the collecting belt 151, and collects and holds it in a sheet-like form.

[0055] This suction chamber 154a is partitioned so that a suction pressure Pa capable of stably holding the descending filament aggregate Fa is generated under the conveying surface of the collection belt 151 in a narrow range approximately equal to the spray area in the transport direction, and the interior of this partitioned range is sucked in by the suction fan 155a to create a negative pressure.

[0056] The suction chambers 154b, 154c respectively suck the filament assemblies Fb, Fc pulled down from the outlets of the injectors 40 of the ejection devices 10B, 10C directly above the collecting belts 152, 153 of the sub-conveyors 52, 53 from below the collecting belt 151, and collect and hold them in a sheet-like form. These sub-conveyors 52, 53 sandwich the sheet-like filament assemblies Fb, Fc collected and held on the collecting belts 152, 153 between the collecting belts 152, 153 below, and send them downstream as filament assemblies Fab, Fabc.

[0057] These suction chambers 154b, 154c are set to negative pressure by driving suction fans 155b, 155c so as to generate suction pressures Pb, Pc capable of stably holding the descending filament assemblies Fb, Fc under the conveying surfaces of the collecting belts 152, 153. Note that, like the suction chamber 154a, these suction chambers 154b, 154c are also suctioned and set to negative pressure by the suction fans 155b, 155c so as to generate the desired suction pressures Pb, Pc in a narrow partitioned range approximately equal to the spray area in the conveying direction of the descending filament assemblies Fb, Fc. At the same time, these suction chambers 154b, 154c are arranged to suction the filament assemblies Fab, Fabc on the collecting belt 151 and ...2, 153 of the sub-conveyors 52, 53. Therefore, the suction chambers 154b, 154c may increase or decrease the suction volume by adjusting the suction range in the transport direction under the collecting belt 151 so that optimal suction pressures Pb, Pc are generated on the collecting belts 152, 153. Similarly, the inside of the collecting belts 152, 153 may be divided into adjustable suction ranges.

[0058] Thereby, the suction chambers 154b and 154c, like the suction chamber 154a, can continuously suck and hold the filament assemblies Fab and Fabc that are increased from the sheet-like filament assembly Fa via the collection belt 151 of the main conveyor 51.

[0059] The suction chambers 154a-2, 154b-2, and 154c-2 continuously suck and hold the sheet-like filament assemblies Fa, Fab, and Fabc on the collection belt 151 of the main conveyor 51 downstream of the suction chambers 154a, 154b, and 154c, respectively.

[0060] The suction chambers 154a-2, 154b-2, and 154c-2 are driven by the suction fan 155a-2 to generate suction pressures Pa-2, Pb-2, and Pc-2 that continuously suck and hold the sheet-like filament aggregates Fa, Fab, and Fabc on the collecting belt 151. The suction chambers 154a-2 and 154b-2 are disposed between the suction chambers 154a, 154b, and 154c, and are continuous to suck without gaps, so that they are installed to suck a wide partition range so as to connect the separate collection positions of each of the ejection devices 10. The suction chamber 154c-2 is installed to suck a shorter partition range because it only delivers the sheet-like filament aggregate Fabc received from the suction chamber 154c to the embossing device 60 adjacent to the downstream side.

[0061] As a result, the suction chambers 154a-2, 154b-2, and 154c-2 can suck and hold the sheet-like filament assemblies Fa, Fab, and Fabc located on the upper surface 151a via the collecting belt 151 of the main conveyor 51 in succession to the suction chambers 154a, 154b, and 154c, respectively. At this time, the sheet-like filament assemblies Fa and Fab on the collecting belt 151 of the main conveyor 51 are sucked and held by the suction chambers 154a-2 and 154b-2, respectively, and are sandwiched between the collecting belts 152 and 153 of the sub-conveyors 52 and 53 without floating up. In addition, the sheet-like filament assemblies Fa and Fab are superimposed on the sheet-like filament assemblies Fb and Fc that are collected and held by the collecting belts 152 and 153 and turned upside down, to become the sheet-like filament assemblies Fab and Fabc, which are then sucked and held and transported downstream.

[0062] As described above, the collecting conveyor 50 is set so that the individual suction fans 155a to 155c-2 suck at a required wind speed so that a suction pressure P sufficient for collecting and holding the sheet-like filament aggregate F is generated for each of the suction chambers 154a to 154c-2 of the suction box 54 on the collecting belt 151 of the main conveyor 51. Note that the relative relationship (strength) of the suction pressure P on the collecting surface (transport surface) of the filament aggregate F for each of the suction chambers 154a to 154c-2 described below will be explained by calculating and substituting a wind speed value according to the separation space from the connection points of the suction fans 155a to 155c-2 to the collecting surface.

[0063] For example, the suction box 54 is adjusted so that the suction pressures Pa, Pb, Pc of the suction chambers 154a, 154b, 154c located at the points where the filament aggregate F is sprayed by the spray devices 10A, 10B, 10C on the collecting conveyor 50 are greater than the suction pressures Pa-2, Pb-2, Pc-2 of the suction chambers 154a-2, 154b-2, 154c-2 located downstream of the respective suction pressures. Also, the suction pressures Ps(Pa, Pa-2) of the suction chambers 154a, 154a-2 at the front in the transport direction of the filament aggregate F, Pm(Pb, Pb-2) of the suction chambers 154b, 154b-2 at the middle, and Ps(Ps, Pb-2) of the suction chambers 154b, 154b-2 at the end are greater than the suction pressures Ps(Pa, Pa-2) of the suction chambers 154a, 154a-2 at the front in the transport direction of the filament aggregate F, Ps(Ps, Pb-2) of the suction chambers 154b, 154b-2 at the back, and Ps(Ps, Pb-2) of the suction chambers 154b, 154b-2 at the back. The suction pressures Pe (Pc, Pc-2) of the tail side suction chambers 154c, 154c-2 are sucked and held on both the upstream and downstream sides, so that the suction pressure Pm at the intermediate position can be adjusted to be smaller than the leading side suction pressure Ps and the tail end side suction pressure Pe (Ps>Pm and Pe>Pm). In addition, the suction pressures Pa, Pb, and Pc are adjusted according to the basis weight of the filament aggregate F on the conveying surface so as not to impede the smooth relative movement of the collecting belt 151 by excessively reducing the pressure inside the suction chambers 154a, 154b, and 154c.

[0064] In detail, the suction chamber 154a is configured to set the suction pressure Pa of the collection belt 151 of the main conveyor 51, which collects and holds the filament aggregate Fa spun by the ejection device 10A in a sheet shape, so that the basis weight of the semi-finished product wound into a roll shape by the winder 70 is, for example, 10 to 30 g / m 2 When manufacturing the nonwoven fabric C, the wind speed Pa is set to 7.5. This suction pressure (wind speed) Pa is set to a relatively strong value so that the filament aggregate Fa is attracted to the upper surface 151a of the collecting belt 151 regardless of its basis weight, since this is the point where the filament aggregate Fa is sucked and begins to be collected and held in a sheet form.

[0065] The suction chamber 154a-2 is connected to the suction chamber 154a in the same manner, with a suction pressure of Pa-2 and a basis weight of 10 to 30 g / m 2 When manufacturing the nonwoven fabric C, the wind speed Pa-2 is set to 3.8. Here, as with the suction pressure Pa, the suction pressure (wind speed) Pa-2 is sufficient to maintain the shape of the filament aggregate Fa that is sucked and held in a sheet shape, regardless of the basis weight (weighing) of the filament aggregate Fa, and is held low at about half the suction pressure Pa because the filament aggregate Fa is sandwiched between the collecting belts 151 and 152 of the main conveyor 51 and the sub-conveyor 52 as it is.

[0066] The suction chamber 154b has a suction pressure Pb of, for example, 10 to 30 g / m 2 When manufacturing the nonwoven fabric C, the wind speed Pb is set to 6.0. Like the suction pressure Pa, the suction pressure (wind speed) Pb is set to a strong value regardless of the basis weight because the filament aggregate Fb is collected and formed into a sheet on the collecting belt 152 of the sub-conveyor 52, but because the filament aggregate Fab on the collecting belt 151 of the main conveyor 51 is sucked in between, the wind speed Pb is set to a low value so as not to restrict the movement of the collecting belt 151.

[0067] The suction chamber 154b-2 is connected to the suction chamber 154b and has a suction pressure Pb-2, for example, a basis weight of 10 to 30 g / m 2When manufacturing the nonwoven fabric C, the wind speed Pa is set to 3.2. Here, as with the suction pressure Pb, the suction pressure (wind speed) Pb-2 is sufficient to maintain the shape of the filament aggregates Fb and Fab sucked and held in a sheet shape, regardless of the basis weight (weighing) of the filament aggregates Fb and Fab, and is set to a very low value because the filament aggregates F are sandwiched between the collecting belts 151 and 153 of the main conveyor 51 and the sub-conveyor 53 as is, and is set so that the filament aggregates F with a smaller basis weight are sucked and held more strongly so that they can be reliably sucked and held and enter between the collecting belts 151 and 153. Note that, on the collecting belt 151 of the main conveyor 51 below the sub-conveyor 53, the sheet-like filament aggregate Fc collected and held by the collecting belt 153 is sandwiched in a state where it is overlapped with the sheet-like filament aggregate Fab, sucked and held, and transferred downstream.

[0068] The suction chamber 154c is configured to have a suction pressure Pc of, for example, 10 to 30 g / m 2 When manufacturing the nonwoven fabric C, the suction pressure (wind speed) Pc is set to Pa=7.4. As with the suction pressures Pa and Pb, the suction pressure (wind speed) Pc is set to a strong value regardless of the basis weight because the filament aggregate Fc is collected and formed on the collecting belt 153 of the sub-conveyor 53, but since the filament aggregate Fc on the collecting belt 151 of the main conveyor 51 is sucked in between, the suction pressure is kept low so as not to restrict the movement of the collecting belt 151. It is being done.

[0069] The suction chamber 154c-2 is connected to the suction chamber 154c and has a suction pressure Pb-2, for example, a basis weight of 10 to 30 g / m 2 When manufacturing the nonwoven fabric C, the suction pressure (wind speed) Pc-2 is set to Pa=3.2 to 3.8. The suction pressure (wind speed) Pc-2 is set lower than the suction pressure Pa according to the basis weight so that the filament aggregate Fabc conveyed from under the sub-conveyor 53 is reliably sucked and held by the collecting belt 151 of the main conveyor 51 and delivered to the embossing device 60.

[0070] In the nonwoven fabric manufacturing apparatus M, the line speed of the collecting belts 151, 152, and 153 is 100 to 1200 m / min. The fiber discharge rate of the ejection devices 10A and 10C is 0.2 to 1.0 g / hole / min, and the fiber discharge rate of the ejection device 10B is 0.2 to 1.0 g / hole / min. The filament aggregates Fa and Fc (crimped fiber layer C1) are produced at a spinning speed of 1200 to 6500 m / s, and the filament aggregate Fb (spunbond fiber layer C2) is produced at a spinning speed of 100 to 1200 m / s. In the nonwoven fabric C produced under these conditions, the fiber diameter in the crimped fiber layer C1 is 8 to 30 μm, and the fiber diameter in the spunbond fiber layer C2 is 30 to 100 μm.

[0071] Incidentally, in the spunbond fiber layer C2, it is necessary to adjust the fibers so that they are oriented almost straight in the MD direction. This adjustment can be performed, for example, by installing an adjustment roller 162 that pulls the spunbond fibers at the line speed on the upper surface 152a of the collection belt 152 of the nonwoven fabric manufacturing apparatus M, so that the fibers can be oriented straight in the MD direction. The adjustment roller 162 may be provided with a cooling function for cooling the fibers.

[0072] Even if the roller 162 is not installed, the fibers can be oriented straight in the MD direction by matching the spinning speed in the jetting device 10B with the line speed of the collection belt 152. The spinning speed in the jetting device 10B can be adjusted by the jetting pressure of the jetting device 10B.

[0073] The spinning speed in the ejection devices 10A and 10C is set to be faster than the line speed of the collection belts 151 and 153. This allows the fibers to be deposited in a loop (spiral) shape on the collection belts 151 and 153, so that a crimped fiber layer C1 can be produced. The crimped fiber layer C1 has a width shrinkage (reduction rate of the original roll width after a width of 230 mm and a load of 2 kg are applied for 30 seconds) suppressed to 15% or less, and a bulkiness (the reciprocal of the density) of 20 or more.

[0074] The manufacturing method described above produces the nonwoven fabric C according to this embodiment. The nonwoven fabric C according to this embodiment maintains its bulkiness and can realize stable operation when used as a material.

[0075] <Other embodiments> Although the embodiments of the present invention have been described above, the above-mentioned various embodiments can be combined as much as possible. The nonwoven fabric C according to the above embodiment has a three-layer structure in which two crimped fiber layers C1 are arranged and a spunbond fiber layer C2 is arranged between them, but the present invention is not limited to this. For example, the nonwoven fabric C may have a two-layer structure in which a crimped fiber layer C1 and a spunbond fiber layer C2 are laminated. In addition, when the nonwoven fabric C has a three-layer structure, the spunbond fiber layer C2 does not have to be arranged between the two crimped fiber layers C1, and for example, the spunbond fiber layer C2, the crimped fiber layer C1, and the crimped fiber layer C1 may be laminated in this order. In addition, the nonwoven fabric C may be configured to have four or more layers as long as it has at least one spunbond fiber layer C2. In addition, the nonwoven fabric manufacturing apparatus M may be configured to have a number of layers according to the nonwoven fabric C to be manufactured. The above can be changed as appropriate.

[0076] In addition, in the nonwoven fabric manufacturing apparatus M, if the fiber discharge speed of the ejection device 10B and the line speed of the repair belt 151 can be matched, the sub-conveyor 52 does not need to be provided. [Explanation of symbols]

[0077] C··Non-woven fabric C1: Crimped fiber layer C2: Spunbond fiber layer M·Nonwoven fabric manufacturing equipment 10, 10A, 10B, 10C...Ejection device 20. Spinning equipment 30·Cold air device 40··Injector 50 Collection conveyor 51 Main conveyor 52, 53 Sub conveyor 54 Suction box 60··Embossing device 70 Winder 141, 142: Signboard 151, 152, 153 Collection belt 154a, 154b, 154c Suction chamber 162 Adjustment roller f filament fr……Rotation diameter F, Fa, Fab, Fabc, Fb, Fc filament assembly Lc Intersection distance Ld...Open interval Lr Evacuation interval P, Pa, Pb, Pc, Pe, Pm, Ps Suction pressure (wind speed)

Claims

1. A method for producing a nonwoven fabric composed of a plurality of fiber layers, comprising the steps of: forming a first fiber layer made of crimped fibers having a crimp number of 15 or more per 25 mm; forming a second fiber layer having a fiber diameter of 2 to 100 denier and fibers oriented in the MD direction; Including, In the step of forming the second fiber layer, the fibers are pulled by a roller at a speed at which the fibers are conveyed in order to orient the fibers in the MD direction. Nonwoven fabric manufacturing method.

2. A nonwoven fabric manufacturing apparatus for manufacturing a nonwoven fabric composed of a plurality of fiber layers, the nonwoven fabric manufacturing apparatus comprising: a fiber spraying device that sprays fibers; and a sheet conveying device that collects the bundle of fibers sprayed from the fiber spraying device on a conveying surface, forms the bundle of fibers into a sheet-like nonwoven fabric, and conveys the bundle in a conveying direction, The fiber spraying device is A first fiber spraying device that sprays filaments in a bundle to form a first fiber layer made of crimped fibers having a crimp number of 15 or more per 25 mm; a second fiber spraying device for spraying filaments in a bundle to form a second fiber layer having a fiber diameter of 2 to 100 denier and fibers oriented in the MD direction; having the nonwoven fabric manufacturing apparatus includes a roller that pulls the fibers forming the second fiber layer at a speed at which the fibers forming the second fiber layer are conveyed in order to orient the fibers forming the second fiber layer in the MD direction; Nonwoven fabric manufacturing equipment.

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