Method for manufacturing short fibers, method for manufacturing nonwoven fabric, short fiber manufacturing device, and nonwoven fabric manufacturing device

Abstract

A method for manufacturing short fibers includes a step of interlacing reduction in which a tow band containing crimped cellulose acetate fibers and having moisture attached is transported in a predetermined transport direction, and a tension is applied to the transport direction, thereby reducing the interlacing of the crimped cellulose acetate fibers in the tow band, and a step of short fiber formation in which the tow band after the interlacing reduction is cut to form short fibers.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to a method for manufacturing staple fibers using crimped cellulose acetate fibers, a method for manufacturing nonwoven fabric, a staple fiber manufacturing apparatus, and a nonwoven fabric manufacturing apparatus. BACKGROUND

[0002] A staple fiber (man-made short fiber) manufactured from crimped cellulose acetate fibers is known. The staple fiber is used, for example, as a material for nonwoven fabric. Nonwoven fabric using the staple fiber exhibits the hand of cellulose acetate fibers, and a soft and pleasant feeling to the skin can be obtained. In addition, a fluffy nonwoven fabric can be manufactured by using staple fibers obtained by cutting crimped cellulose acetate fibers.

[0003] In the case of manufacturing staple fibers from crimped cellulose acetate fibers, for example, after a tow band including the fibers is drawn out from a package, the entanglement of the fibers in the tow band is slowed down to make the fibers easy to handle. Thereafter, the tow band is cut by a cutter to form staple fibers. As a form of the cutter, for example, a guillotine type shown in Patent Literature 1, a rotary type shown in Patent Literature 2, and the like are known. In the case of manufacturing nonwoven fabric, a plurality of staple fibers formed are subjected to a carding process in advance. Thereby, the plurality of staple fibers are spread in a sheet shape and the flow direction of the fibers is aligned.

[0004] PRIOR ART DOCUMENTS

[0005] PATENT LITERATURE

[0006] Patent Literature 1: Japanese Patent Application Laid-Open No. 2000-141290

[0007] Patent Literature 2: Japanese Patent Application Laid-Open No. H1-148818 SUMMARY

[0008] PROBLEMS TO BE SOLVED BY THE INVENTION

[0009] Crimped cellulose acetate fibers are fluffy and elastic, and have a high degree of polymerization. Therefore, staple fibers composed of crimped cellulose acetate fibers sometimes get hooked on a staple fiber manufacturing apparatus or clog in a conveyance path. In addition, staple fibers composed of crimped cellulose acetate fibers are unstable in length dimension due to unevenness in the posture with respect to a cutter. Thereby, the manufacturing efficiency of staple fibers is reduced.

[0010] Therefore, an object of the present disclosure is to enable staple fibers of uniform length dimension to be efficiently manufactured in the case of manufacturing staple fibers using crimped cellulose acetate fibers.

[0011] The present inventors conducted research, and as a result, it was confirmed that a tow band including crimped cellulose acetate fibers can be extended by adding moisture and the entanglement of the fibers is slowed down. The present disclosure is based on such recognition.

[0012] That is, the method for manufacturing short fibers according to one aspect of the present disclosure includes: a crimping reduction step of, with respect to a tow band in which crimped cellulose acetate fibers are contained and moisture is attached, imparting a tension to a predetermined conveying direction in which the tow band is conveyed, thereby reducing crimping of the crimped cellulose acetate fibers in the tow band; and a short fiber formation step of cutting the tow band in which the crimping is reduced to form short fibers.

[0013] According to the above-described method, in the crimping reduction step, the crimping of the plurality of cellulose acetate fibers to which moisture is attached is reduced, and the elasticity of the cellulose acetate fibers at the time of cutting the tow band is lowered. Thus, the formed short fibers are prevented from, for example, being hooked to the short fiber manufacturing device or clogging in the conveying path. In addition, it is possible to suppress unevenness in the posture of the fibers with respect to the knife at the time of cutting the tow band in the short fiber formation step. As a result, it is possible to form short fibers of uniform length dimensions. Thus, it is possible to efficiently manufacture stable quality short fibers by a relatively simple method.

[0014] In the crimping reduction step, it is also possible to attach moisture to the tow band in such a manner that the amount of moisture of the tow band immediately before cutting in the short fiber formation step becomes a value in a range of 7% by mass or more and 80% by mass or less. Thus, it is possible to easily attach an appropriate amount of moisture necessary for forming short fibers of uniform length dimensions by extending the tow band to reduce the crimping of the fibers to the tow band. Thus, it is possible to reduce the load applied to the short fibers at the time of drying the short fibers. In addition, it is possible to make the manufacturing equipment less likely to be wetted with water. Thus, it is possible to reduce the burden of equipment management.

[0015] In the crimping reduction step, it is also possible to promote the reduction of the crimping by heating the tow band. In this way, by heating the tow band, it is possible to plasticize the cellulose acetate fibers in the tow band at the time of cutting within a certain range, and lower the elasticity of the cellulose acetate fibers. Thus, it is possible to further reduce the crimping of the cellulose acetate fibers in the tow band.

[0016] In the crimping reduction step, it is also possible to attach moisture to the tow band by bringing a mist containing moisture into contact with the tow band. Thus, it is possible to prevent the tow band from being excessively wetted. Thus, it is possible to reduce the amount of water used for reducing the crimping of the fibers of the tow band. In addition, it is possible to reduce the load of the work amount and energy consumption for drying the tow band after the crimping reduction step. In addition, by the tow band to which moisture is attached, it is possible to reduce the tow band from being excessively wetted in the short fiber manufacturing device.

[0017] The mist can also contain a vapor of moisture. Thereby, the tow band can be more favorably prevented from being excessively drenched with moisture. Further, in this case, in the entanglement relaxation step, the mist can also be brought into contact with the tow band in such a manner that the amount of moisture of the tow band immediately before being cut in the staple fiber forming step becomes a value in the range of 7 mass% or more and 15 mass% or less. Thereby, an appropriate amount of moisture for relaxing the entanglement of the fibers of the tow band can be obtained, and the tow band can be more favorably prevented from being excessively drenched with moisture.

[0018] In the entanglement relaxation step, the mist can also be brought into contact with the tow band in such a manner that the amount of moisture of the tow band immediately before being cut in the staple fiber forming step becomes a value in the range of 7 mass% or more and 35 mass% or less. Further, a drying step of drying the moisture attached to the staple fibers can also be provided after the staple fiber forming step.

[0019] In the staple fiber forming step, the tow band can also be cut by a rotary-type cutter having a cutting edge arranged on a peripheral surface and being supported by a shaft and being rotationally driven in such a manner that the tow band comes into contact with the cutting edge. By using such a rotary-type cutter, the tow band being conveyed can be continuously cut, and the staple fibers can be more efficiently formed.

[0020] Further, the nonwoven fabric manufacturing method of one aspect of the present disclosure manufactures a nonwoven fabric using the staple fibers formed by any one of the above-described staple fiber manufacturing methods.

[0021] Further, the staple fiber manufacturing apparatus of one aspect of the present disclosure includes: an entanglement relaxation section that, with respect to a tow band that is being conveyed in a predetermined conveying direction, contains crimped cellulose acetate fibers and has moisture attached thereto, imparts a tension to the conveying direction, thereby relaxing the entanglement of the crimped cellulose acetate fibers in the tow band; and a staple fiber forming section that cuts the tow band after the entanglement has been relaxed to form staple fibers.

[0022] Further, the nonwoven fabric manufacturing apparatus of one aspect of the present disclosure includes: the staple fiber manufacturing apparatus; and a nonwoven fabric forming section that forms a nonwoven fabric using the staple fibers formed by the staple fiber forming section.

[0023] Advantages

[0024] According to the aspects of the present disclosure, in the case where staple fibers are manufactured using crimped cellulose acetate fibers, the staple fibers of a uniform length size can be efficiently manufactured. BRIEF DESCRIPTION OF DRAWINGS

[0025] Figure 1 is a schematic view of a nonwoven fabric manufacturing apparatus of a first embodiment.

[0026] Figure 2 is a schematic view showing the internal structure of the cutting mechanism possessed by the short fiber forming section Figure 1

[0027] Figure 3 is a schematic view showing the internal structure of the cutting mechanism possessed by the short fiber forming section

[0028] Figure 4 is a photograph taken of the tow band after the just-interlaced slowdown of Example 1.

[0029] Figure 5 is a photograph taken of the tow band after the just-interlaced slowdown of Example 2. DETAILED DESCRIPTION

[0030] Each embodiment of the present disclosure will be described with reference to the drawings.

[0031] (First Embodiment)

[0032] Figure 1 is a schematic view showing the internal structure of the cutting mechanism possessed by the short fiber forming section Figure 2 Figure 1 Figure 1 The nonwoven fabric manufacturing apparatus 1 shown in the drawing extracts a veil-like tow band 60 folded in a roll from a packaging box B, and forms short fibers 62 using the tow band 60. That is, the nonwoven fabric manufacturing apparatus 1 of the present embodiment functions as a short fiber manufacturing apparatus as well. The short fibers 62 are used as a material for a nonwoven fabric 63. The nonwoven fabric referred to in the present specification means a nonwoven fabric according to JIS L 0222:2001.

[0033] The tow band 60 includes crimped cellulose acetate fibers 61 (hereinafter, also referred to as CA fibers 61). The tow band 60 has stretchability by virtue of this. In addition, the tow band 60 is in a state in which a plurality of CA fibers 61 are interlaced with each other. The CA fibers 61 in the tow band 60 extracted from the packaging box B are long fibers. The CA fibers 61 are crimped in a primary crimp that is the smallest crimp unit, and are crimped in a secondary crimp that is a crimp unit larger than the primary crimp. The CA fibers 61 can also be crimped in a high crimp that is a crimp unit larger than the secondary crimp.

[0034] ​​​The TD (Total Denier) and FD (Filament Denier) of the yarn tow 60 can be appropriately set. As an example, the TD of the yarn tow 60 can be a value of millions, hundreds of thousands, tens of thousands, or thousands of units. In another example, the TD of the yarn tow 60 can be a value in the range of 3 million to 5 million, more preferably in the range of 1 million to 2 million. In yet another example, the TD of the yarn tow 60 can be a value in the range of 100,000 to 700,000, more preferably in the range of 100,000 to 300,000. Furthermore, in yet another example, the TD of the yarn tow 60 can be a value in the range of 5,000 to 100,000, more preferably in the range of 10,000 to 50,000.

[0035] Furthermore, as an example, the FD of the yarn bundle 60 is a value in the range of 10 or less. In another example, the FD of the yarn bundle 60 is a value in the range of 1 or more and 8 or less. The yarn bundle 60 of this embodiment is conveyed in a predetermined conveying path 50 provided in the nonwoven fabric manufacturing apparatus 1 while being given a relatively weak tension (load) in the conveying direction P with a value in the range of 2 mgf or more and 50 mgf or less per dendrite.

[0036] like Figure 1 and Figure 2 As shown, the nonwoven fabric manufacturing apparatus 1 includes: a guiding member 7 for guiding a yarn bundle 60 extracted from a packaging box B; and a plurality of guiding rollers R1 to R4, which are separately arranged in a predetermined conveying direction P to guide the yarn bundle 60. Furthermore, the nonwoven fabric manufacturing apparatus 1 includes: an entanglement reduction section 2, disposed midway along the conveying path 50 of the yarn bundle 60 to reduce the entanglement of CA fibers 61 in the yarn bundle 60; and a short fiber forming section 3, which cuts the yarn bundle 60 after the entanglement of CA fibers 61 has been reduced to form short fibers 62. Additionally, the nonwoven fabric manufacturing apparatus 1 includes: a drying section 4 for drying the short fibers 62 discharged from the short fiber forming section 3; and a nonwoven fabric forming section 5 for entanglement of the short fibers 62 passing through the drying section 4 to form a nonwoven fabric 63.

[0037] The entangling relaxation section 2 applies moisture to the tow band 60 that is being conveyed in the conveying direction P and contains crimped CA fibers 61 while giving a tension to the tow band 60 in the conveying direction P. As one example, the entangling relaxation section 2 adjusts the tension applied to the tow band 60 by changing the rotational speed of the rotating roller 21 described later. The tension is applied to the tow band 60 from before the tow band 60 is introduced into the entangling relaxation section 2 to before the tow band 60 is cut by the cutting mechanism 30 of the staple fiber forming section 3. Thus, the entangling relaxation section 2 extends the CA fibers 61 to relax the entangling of the CA fibers 61 in the tow band 60. The entangling relaxation section 2 of the present embodiment applies moisture to the tow band 60 by bringing the mist M into contact with the tow band 60. The mist M referred to in the present specification is a particle of a liquid that is dispersed in a gas and contains moisture. At least either of vapor and a fine droplet is contained in the mist M.

[0038] Note that the tension applied to the tow band 60 can be adjusted, for example, by changing the load from the rotating roller 21 to the tow band 60. For example, in this case, when the relative position of the rotating roller 21 with respect to the tow band 60 is moved downward, the tension applied to the tow band 60 increases. Also, for example, when the relative position of the rotating roller 21 with respect to the tow band 60 is moved upward, the tension applied to the tow band 60 decreases. Also, the tension applied to the tow band 60 can be adjusted by changing the material of the rotating roller 21 or fixing the relative position of the rotating roller 21 with respect to the tow band 60 to a prescribed position.

[0039] As one example, the mist M of the present embodiment contains vapor. Also, in the present embodiment, the vapor is heated vapor. The temperature of the heated vapor can be appropriately set, but as one example, is a temperature higher than room temperature (25°C). Also, in another example, the vapor is superheated vapor superheated to a temperature above the boiling point (100°C). As one example, the particle diameter of the vapor is a value in the range of 0.3 nm or more and 40 nm or less. The entangling relaxation section 2 applies moisture to the tow band 60 while heating the tow band 60 by bringing the heated vapor into contact with the tow band 60.

[0040] The entangling relaxation section 2 has a housing 20 in which the mist M is filled, at least one rotating roller 21 that is shaft-supported in the inside of the housing 20 and winds the tow band 60 around the peripheral surface, and at least one nozzle 22 that sprays the mist M to the tow band 60 in the inside of the housing 20. The supply pipe 23 that supplies moisture from the outside of the entangling relaxation section 2 to the nozzle 22 is connected to the rear end of the nozzle 22. For example, when the rotational speed of the rotating roller 21 is increased, the tension applied to the tow band 60 increases. Also, when the rotational speed of the rotating roller 21 is decreased, the tension applied to the tow band 60 decreases.

[0041] The entangling slowdown portion 2 adds moisture to the tow band 60, whereby the moisture amount of the tow band 60 immediately before being cut in the staple fiber forming portion 3 is more than the moisture amount (equilibrium moisture rate according to JIS L 1013:2010) of the tow band 60 before the moisture is added by the entangling slowdown portion 2. As one example, the entangling slowdown portion 2 of the present embodiment adjusts the spray amount of the mist M in such a manner that the moisture amount of the tow band 60 immediately before being cut in the staple fiber forming portion 3 becomes a value in a range of 7 mass% or more and 80 mass% or less. The spray amount of the mist M is adjusted, for example, in accordance with at least either one of the supply amount of moisture per unit time to the nozzle 22 and the conveyance speed of the tow band 60. The spray amount of the mist M is adjusted to a value in the above-described range, whereby it is easy to secure the moisture amount required for plasticizing the CA fibers 61 in the tow band 60 as described later, and adjustment is made so as not to cause excess of the moisture amount. The entangling slowdown portion 2 of the present embodiment also brings the mist M into contact with the tow band 60 in such a manner that the moisture amount of the tow band 60 immediately before being cut in the staple fiber forming portion 3 becomes a value in a range of 7 mass% or more and 15 mass% or less.

[0042] At least one additive among an oil agent, a softening agent, and an antistatic agent, and the like can also be contained in the mist M. By adding the additive to the CA fibers 61, it is possible to change the properties of the nonwoven fabric 63 by the additive. Further, by adjusting at least either one of the spray amount of the mist M and the spray direction of the mist M from the nozzle 22, it is possible to locally add the additive to the CA fibers 61 in the tow band 60. It is also possible to add the additive to the tow band 60 separately from the mist M for the purpose of adjusting the addition amount of these additives separately from the moisture amount added to the tow band 60.

[0043] The staple fiber forming portion 3 is a long fiber bundle cutting portion. The staple fiber forming portion 3 has a cutting mechanism 30 that cuts the CA fibers 61 into a prescribed length dimension to form the staple fibers 62, and a carding machine 31 that performs carding processing on the plurality of staple fibers 62 formed. The cutting mechanism 30 has a guide roller (push roller) 32 that is rotatably supported so as to guide the tow band 60 in contact with the peripheral surface, and a rotary cutter 33 that cuts the tow band 60 guided by the guide roller 32. The rotary cutter 33 has a cutting edge 34 disposed on the peripheral surface and is rotatably supported. The guide roller 32 and the rotary cutter 33 are rotationally driven in such a manner that the cutting edge 34 of the rotary cutter 33 comes into contact with the tow band 60 conveyed on the peripheral surface of the guide roller 32. Note that the structure obtained by combining the guide roller 32 and the rotary cutter 33 is also referred to as an EC cutter.

[0044] In this embodiment, the distance between the tip of the cutting blade 34 and the circumferential surface of the guide roller 32 is set to the distance at which the outermost CA fiber 61 of the filament bundle 60 wound around the circumferential surface of the guide roller 32 contacts the cutting blade 34 and is cut. The length of the short fiber 62 formed by the short fiber forming section 3 can be appropriately set. As an example, the length of the short fiber 62 in this embodiment is a value in the range of 1 mm or more and 80 mm or less. In another example, the length of the short fiber 62 is a value in the range of 1 mm or more and 9 mm or less. In yet another example, the length of the short fiber 62 is a value in the range of 30 mm or more and 80 mm or less. The length of the short fiber 62 is not limited to these values.

[0045] The drying section 4 includes a conveying mechanism 40 for conveying short fibers 62 discharged from the short fiber forming section 3, and a heating section 41 for heating the short fibers 62 conveyed by the conveying mechanism 40 to dry them. The nonwoven fabric forming section 5 forms a nonwoven fabric 63 by intertwining the dried short fibers 62 with each other. Furthermore, the nonwoven fabric forming section 5 adjusts the thickness, feel, or fiber spacing of the nonwoven fabric 63 by adjusting the intertwining of the dried short fibers 62. It should be noted that, in the case of only constituting a short fiber manufacturing apparatus, for example, the carding machine 31 and the nonwoven fabric forming section 5 may be omitted.

[0046] like Figure 1 and Figure 2 As shown, when the nonwoven fabric manufacturing apparatus 1 is driven, a yarn-like filament bundle 60 is drawn from the packaging box B. The filament bundle 60 is guided by the guide member 7 and guide rollers R1 to R4 while being conveyed in the conveying direction P. The conveyed filament bundle 60 is introduced into the interior of the housing 20 filled with mist M in the winding deceleration section 2. The filament bundle 60 is conveyed inside the housing 20 while being wound around the circumference of the rotating roller 21.

[0047] At this time, the fiber bundle 60 is subjected to a relatively weak tension (load) in the conveying direction P, ranging from 2 mgf to 50 mgf per ounce, while being coated with mist M by at least one nozzle 22. As an example, the nozzle 22 sprays mist M onto the fiber bundle 60 from multiple directions, including directions perpendicular to the surface of the fiber bundle 60. After contacting the surface of the fiber bundle 60, the mist M penetrates into the interior of the fiber bundle 60. Furthermore, the fiber bundle 60 has abundant fiber gaps. Therefore, the mist M directly contacts multiple CA fibers 61 inside and outside the fiber bundle 60 through the fiber gaps. This coats the multiple CA fibers 61 contained in the fiber bundle 60 with moisture. Each CA fiber 61 is plasticized by the coated moisture, thereby slowing down the high degree of shrinkage, which is at least twice.

[0048] In this embodiment, nozzle 22 sprays heated steam onto the fiber bundle 60. The CA fibers 61 in the fiber bundle 60 are plasticized by both moisture and heat when heated with the added heated steam. This reduces the elasticity of the multiple CA fibers 61, thereby promoting the reduction of entanglement. In this embodiment, by adding moisture to the fiber bundle 60 and heating it, the CA fibers 61 can be easily plasticized. This reduces the amount of moisture used to reduce the entanglement of the CA fibers 61.

[0049] The yarn bundle 60, passing through the entanglement reduction section 2, is conveyed to the short fiber forming section 3 in the conveying direction P under the aforementioned tension. In this embodiment, the amount of moisture sprayed onto the yarn bundle 60 by steam in the entanglement reduction section 2 is relatively small. Therefore, there is no need for a process of removing excess moisture from the yarn bundle 60 between the entanglement reduction section 2 and the short fiber forming section 3. This simplifies the nonwoven fabric manufacturing apparatus 1.

[0050] The conveyed filament bundle 60 is guided into the cutting mechanism 30 in the short fiber forming section 3. For example... Figure 2 As shown, at this time, the fiber bundle 60, under the aforementioned tension, is guided and conveyed on the circumferential surface of the rotary guide roller 32, thereby contacting the cutting edge 34 of the rotary cutter 33. As a result, the CA fibers 61 in the fiber bundle 60 are cut to a predetermined length to form multiple short fibers 62.

[0051] In this embodiment, the moisture content of the yarn bundle 60 introduced into the cutting mechanism 30 is relatively low. Therefore, for example, it prevents the yarn bundle 60 containing excessive moisture from clogging between the guide roller 32 and the rotary cutter 33, or prevents the CA fibers 61 in the yarn bundle 60 from sticking to the guide roller 32 or the rotary cutter 33 due to moisture, making them difficult to discharge. Furthermore, in this embodiment, multiple CA fibers 61 of the yarn bundle 60 are cut by the cutting blade 34 while their entanglement is reduced and tension is applied. Therefore, the posture of the CA fibers 61 relative to the cutting blade 34 is stable. As a result, the yarn bundle 60 is cut by the rotary cutter 33 with a uniform length dimension. The resulting short fibers 62 are continuously discharged from the short fiber forming section 3. In this embodiment, by employing the rotary cutter 33, short fibers 62 are formed while the yarn bundle 60 is being fed. Therefore, short fibers 62 are formed efficiently.

[0052] The resulting short fibers 62 are then carded through a carding machine 31. This process adjusts the thickness and flow direction of the short fibers 62. In this embodiment, the short fibers 62 introduced into the carding machine 31 are plasticized by the addition of moisture. Therefore, the short fibers 62 are effectively carded while being prevented from tangling in the carding machine 31 or getting caught on its needles.

[0053] like Figure 1 As shown, multiple short fibers 62 that have undergone carding are conveyed in the conveying direction P and thus introduced into the drying section 4. The short fibers 62 are conveyed by the conveying mechanism 40 and dried by the heating section 41. Thus, the short fibers 62 are dried to a predetermined moisture content. The moisture content of the short fibers 62 introduced into the drying section 4 is not excessive. Therefore, in the drying section 4, the short fibers 62 are dried relatively lightly, and the load received due to heating is reduced. The multiple short fibers 62 passing through the drying section 4 are introduced into the nonwoven fabric forming section 5. In the nonwoven fabric forming section 5, as an example, the multiple short fibers 62 are intertwined based on a needle-punching method. Thus, a nonwoven fabric 63 is formed.

[0054] In the entanglement reduction section 2, moisture is added to the yarn bundle 60, causing it to extend. As a result, in the short fiber forming section 3, the elasticity of the CA fibers 61 when the yarn bundle 60 is cut is reduced, and the curling of the CA fibers 61 becomes slower. Subsequently, the moisture content of the short fibers 62 is reduced through drying. As a result, in the nonwoven fabric forming section 5, the hand feel of the CA fibers 61 is utilized, resulting in a soft, skin-friendly nonwoven fabric 63.

[0055] It should be noted that, in addition to needle punching, other known methods such as dry bonding, wet bonding, chemical bonding, and water-jet interlocking can also be used as methods for forming the nonwoven fabric 63 in the nonwoven fabric forming section 5. The nonwoven fabric 63 discharged from the nonwoven fabric forming section 5 is cut into a predetermined length as needed. Furthermore, if the moisture content of the multiple short fibers 62 introduced into the nonwoven fabric forming section 5 is appropriate, the drying section 4 can be omitted.

[0056] Thus, the method for manufacturing short fibers 62 in this embodiment includes: an entanglement reduction step, in which tension is applied to a yarn bundle 60 containing coiled CA fibers 61 and coated with moisture, which is conveyed in a predetermined conveying direction P, thereby reducing the entanglement of CA fibers 61 in the yarn bundle 60; and a short fiber forming step, in which the yarn bundle 60 with reduced entanglement of CA fibers 61 is cut to form short fibers 62. In the short fiber forming step of this embodiment, the yarn bundle 60 with reduced entanglement of CA fibers 61 is cut while under the applied tension to form short fibers 62.

[0057] Further, as one example, the method of manufacturing the short fibers 62 of the present embodiment has a preparation step of performing preparation for adding moisture to the tow band 60 in the entanglement relaxation step (for example, setting of the entanglement relaxation section 2 and the like in the present embodiment) before the entanglement relaxation step. Further, as one example, the method of manufacturing the short fibers 62 of the present embodiment has a drying step of drying the moisture adhering to the short fibers 62 after the short fiber forming step. Further, the method of manufacturing the nonwoven fabric 63 of the present embodiment uses the manufactured short fibers 62 to manufacture the nonwoven fabric 63.

[0058] As explained above, the method of manufacturing the nonwoven fabric 63 of the present embodiment has the entanglement relaxation step and the short fiber forming step. According to this manufacturing method, in the entanglement relaxation step, the entanglement of the plurality of CA fibers 61 that are crimped and to which moisture is added is relaxed, and the elasticity of the CA fibers 61 at the time of cutting the tow band 60 is reduced. Therefore, it is possible to prevent the formed short fibers 62 from, for example, hooking to the nonwoven fabric manufacturing device 1 or clogging in the conveyance path 50 in the nonwoven fabric manufacturing device 1. Further, it is possible to suppress unevenness in the posture of the CA fibers 61 with respect to the knife 33 at the time of cutting the tow band 60 in the short fiber forming step. As a result, it is possible to efficiently form short fibers 62 of uniform length dimensions. Thus, it is possible to efficiently manufacture stable quality short fibers 62 by a relatively simple method.

[0059] Further, according to the above manufacturing method, moisture is added to the tow band 60 and a tension is imparted to the conveyance direction P, whereby it is possible to extend the CA fibers 61 and relax the entanglement of the plurality of CA fibers 61. Therefore, it is not necessary to, for example, mechanically open the tow band 60 using an opening roller, or open the tow band 60 using a gas using a gas opening device. Thus, it is possible to seek simplification of the nonwoven fabric manufacturing device 1. Further, according to the present embodiment, even if a tow band 60 that is composed of crimped CA fibers 61 in a fluffy manner is used, it is possible to efficiently form short fibers 62 of uniform length dimensions.

[0060] Further, according to the above manufacturing method, by performing the entanglement relaxation step using moisture, it is possible to efficiently form short fibers 62 of uniform length dimensions. Therefore, for example, it is not necessary to have a process of, for example, deteriorating the tow band 60 by a chemical agent to reduce the crimp number before forming the short fibers 62 and the like. Further, in the entanglement relaxation step, moisture is used, and therefore it is possible to efficiently form short fibers 62 by a relatively safe method. Further, according to the above method, even if the entanglement relaxation step is performed, it is possible to maintain the crimp of the short fibers 62 to some extent. Thus, it is possible to manufacture a fluffy nonwoven fabric 63 using crimped short fibers 62.

[0061] Further, in the short fiber forming step of the present embodiment, the tow band 60 whose entangling of the CA fibers 61 is slowed down is cut in a state where the tension is applied to form the short fibers 62. Thereby, the posture of the CA fibers 61 at the time of cutting the tow band 60 can be more stabilized. Thereby, the short fibers 62 of a uniform length dimension can be more easily formed.

[0062] Further, in the entangling slowing step of the present embodiment, moisture is added to the tow band 60 in a manner such that the moisture amount of the tow band 60 immediately before cutting in the short fiber forming step becomes a value in a range of 7% by mass or more and 80% by mass or less. Thereby, the moisture necessary for forming the short fibers 62 of a uniform length dimension by extending the tow band 60 to slow down the entangling of the CA fibers 61 can be easily added to the tow band 60 in an appropriate amount. Thereby, the load applied to the short fibers 62 at the time of drying the short fibers 62 can be reduced. Further, the manufacturing equipment can be less likely to be soaked with water. Thereby, the burden of equipment management can be alleviated.

[0063] Further, in the entangling slowing step of the present embodiment, the slowing down of the entangling of the CA fibers 61 is promoted by heating the tow band 60. In this way, by heating the tow band 60, the CA fibers 61 in the tow band 60 at the time of cutting can be plasticized within a certain range, and the elasticity of the short fibers 62 can be reduced. Thereby, the entangling of the CA fibers 61 in the tow band 60 can be further slowed down.

[0064] Further, in the entangling slowing step, the moisture is added to the tow band 60 by bringing the mist M containing moisture into contact with the tow band 60. Thereby, for example, the tow band 60 can be prevented from being excessively soaked with moisture. Thereby, the amount of water used for slowing down the entangling of the CA fibers 61 can be reduced. Further, the load of the amount of work and the energy consumption for drying the tow band 60 after the entangling slowing step can be reduced. Further, by the tow band 60 to which moisture is added, the nonwoven fabric manufacturing device 1 can be less likely to be excessively soaked with water.

[0065] Further, the mist M contains vapor of moisture. Thereby, the tow band 60 can be more favorably prevented from being excessively soaked with moisture. Further, in the entangling slowing step, the mist M is brought into contact with the tow band 60 in a manner such that the moisture amount of the tow band 60 immediately before cutting in the short fiber forming step becomes a value in a range of 7% by mass or more and 15% by mass or less. Thereby, the moisture amount appropriate for slowing down the entangling of the CA fibers 61 in the tow band 60 can be obtained, and the tow band 60 can be more favorably prevented from being excessively soaked with moisture.

[0066] Further, as one example, the method of manufacturing the nonwoven fabric 63 of the present embodiment has a drying step of drying moisture adhering to the staple fibers 62 after the staple fiber forming step. Thereby, the staple fibers 62 containing water can be prevented from adhering to the nonwoven fabric manufacturing apparatus 1. Further, the nonwoven fabric 63 formed can be prevented from containing unnecessary moisture.

[0067] Further, as one example, in the staple fiber forming step, the tow band 60 is cut by the rotary-type cutter 33 having the cutting edge 34 arranged on the peripheral surface and supported by a shaft and rotationally driven in a manner that the tow band 60 contacts the cutting edge 34. By using the rotary-type cutter 33 of such a configuration, the tow band 60 conveyed can be continuously cut, and the staple fibers 62 can be formed more efficiently.

[0068] Note that the cutting mechanism 30 can have, for example, a guillotine-type cutter as disclosed in Patent Document 1, and a feeder that feeds the tow band 60 to the guillotine-type cutter, instead of the rotary-type cutter 33. The guillotine-type cutter can have at least either one of a pair of edges (e.g., a lower edge and an upper edge) for cutting the tow band 60. In the case of using the guillotine-type cutter, the tension given to the tow band 60 is adjusted by, for example, a feeding speed of the feeder. As one example, when the feeding speed of the feeder is increased, the tension is increased. Further, when the feeding speed of the feeder is decreased, the tension is decreased. However, in the case where the cutting mechanism 30 has the rotary-type cutter 33, the staple fibers 62 are formed at a relatively high speed. Therefore, for example, the manufacturing efficiency of the nonwoven fabric 63 using the rotary-type cutter 33 is improved. Further, in the case where the tow band 60 is heated in the entangling relaxation step, the process of adding moisture to the tow band 60 and the process of heating the tow band 60 can be performed separately. In this case, for example, after moisture is added to the tow band 60, the tow band 60 is heated, whereby the temperature of the tow band 60 can be prevented from decreasing due to the addition of moisture.

[0069] Further, either one of the tow band 60 or a bundle of the tow bands 60 containing a plurality of tow bands 60 can be introduced to the entangling relaxation section 2 and the staple fiber forming section 3. In the present embodiment, the nonwoven fabric 63 is efficiently manufactured as described above. Therefore, even in the case where the bundle of the tow bands 60 is used to manufacture the nonwoven fabric 63, the nonwoven fabric 63 can be favorably manufactured. Hereinafter, other embodiments will be described focusing on differences from the first embodiment.

[0070] (Second Embodiment)

[0071] The entangling-reducing section 2 of the nonwoven fabric manufacturing apparatus 1 of the second embodiment sprays mist M to the tow band 60 by the nozzle 22 as with the first embodiment. The mist M contains minute droplets of moisture. The minute droplets have a particle diameter larger than that of vapor. As one example, the minute droplets have a particle diameter in the range of 0.1 μm or more and 100 μm or less.

[0072] Further, as with the first embodiment, as one example, the method of manufacturing the nonwoven fabric 63 of the present embodiment also has a preparation step of performing preparation for adding moisture to the tow band 60 in the entangling-reducing step before the entangling-reducing step. Further, as one example, it has a drying step of drying the moisture attached to the staple fibers 62 after the staple fiber forming step.

[0073] In the entangling-reducing step, the tow band 60 is sprayed with moisture in the form of minute droplets while being given a weak tension (load) in the range of 2 mgf or more and 50 mgf or less per 1 denier in the conveyance direction P. The CA fibers 61 in the tow band 60 are plasticized by the moisture in the form of minute droplets and are reduced in elasticity. Thus, the entangling of the CA fibers 61 with each other is reduced. Further, as with the first embodiment, the present embodiment also adds moisture to the tow band 60 in the entangling-reducing step in such a manner that the moisture amount of the tow band 60 immediately before being cut in the staple fiber forming step becomes a value in the range of 7 mass% or more and 80 mass% or less. As one example, in the entangling-reducing step, the mist M is brought into contact with the tow band 60 in such a manner that the moisture amount of the tow band 60 immediately before being cut in the staple fiber forming step becomes a value in the range of 7 mass% or more and 35 mass% or less (in another example, a value in the range of 15 mass% or more and 35 mass% or less). As with the first embodiment, the mist M can also contain an additive. According to the present embodiment, by using moisture in the form of minute droplets, a larger amount of additive than in the first embodiment can be added to the CA fibers 61.

[0074] In the present embodiment, the mist M containing moisture is efficiently added to the tow band 60, for example, by using an existing spray device or the like. Thus, the moisture can be added to the tow band 60 at a lower cost. Further, in the case where the crimped CA fibers 61 (tow band 60) are used to manufacture the nonwoven fabric 63, the staple fibers 62 of uniform length can also be efficiently formed. Further, in the present embodiment, the moisture added to the tow band 60 in the entangling-reducing section 2 is also relatively small. Thus, a process of removing excess moisture contained in the tow band 60 between the entangling-reducing section 2 and the staple fiber forming section 3 can be omitted.

[0075] Further, in the entanglement relaxation step of the present embodiment, the moisture amount of the tow band 60 immediately before the cutting in the short fiber forming step is made to be a value in the range of 7 mass% or more and 35 mass% or less in such a manner that the mist M is brought into contact with the tow band 60. Thereby, the moisture amount attached to the tow band 60 can be set to an appropriate amount. Note that, in the present embodiment, the mist M including the heated fine droplets can also be sprayed to the tow band 60 in the entanglement relaxation step. In this case, similarly to the first embodiment, the CA fibers 61 in the tow band 60 are plasticized by both the moisture and the heat.

[0076] (Third Embodiment)

[0077] Figure 3 is a schematic diagram of the nonwoven fabric manufacturing apparatus 11 of the third embodiment. Figure 3 The entanglement relaxation section 12 provided in the nonwoven fabric manufacturing apparatus 11 illustrated has a function of attaching moisture to the tow band 60 by immersing the tow band 60 in water in a state where a tension is imparted to the tow band 60, and relaxing the entanglement of the CA fibers 61 in the tow band 60. The entanglement relaxation section 12 has a storage section 25 that stores water, and at least one rotating roller 26 that is supported on an inside of the storage section 25 and has the tow band 60 wound around a peripheral surface thereof. The tow band 60 is wound around the peripheral surface of the rotating roller 26, and is immersed in the water in the storage section 25 while being imparted with a tension in the conveyance direction P to attach moisture thereto. The water in the storage section 25 can also be at a temperature higher than room temperature (25°C). That is, in the present embodiment, the relaxation of the entanglement of the CA fibers 61 can also be promoted by heating the tow band 60 in the entanglement relaxation step.

[0078] As one example, the manufacturing method of the nonwoven fabric 63 of the present embodiment also has a preparation step of performing preparation (as one example, setting of the entanglement relaxation section 12 and the like in the present embodiment) of attaching moisture to the tow band 60 in the entanglement relaxation step before the entanglement relaxation step. Further, as one example, the manufacturing method of the nonwoven fabric 63 of the present embodiment also has a drying step of drying the moisture attached to the short fibers 62 after the short fiber forming step.

[0079] Further, in the entanglement relaxation step of the present embodiment, the moisture is attached to the tow band 60 immediately before the cutting in the short fiber forming step in such a manner that the moisture amount of the tow band 60 becomes a value in the range of 7 mass% or more and 80 mass% or less. Further, as one example, in the entanglement relaxation step, the moisture is attached to the tow band 60 immediately before the cutting in the short fiber forming step in such a manner that the moisture amount of the tow band 60 becomes a value in the range of 60 mass% or more and 80 mass% or less.

[0080] For the amount of moisture of the tow band 60 immediately before the cutting-off in the short fiber forming step, it is preferable that, for example, the tow band 60 immersed in water does not drip in a natural state to an extent (a value in the range of less than 100% by mass, preferably a value in the range of 80% by mass or less). Further, the amount of water (the amount of water in the storage portion 25) for immersing the tow band 60 in water is set to an extent that the load provided to the short fiber 62 when the short fiber 62 is dried does not become excessive. Thereby, the amount of water added to the tow band 60 is adjusted to be appropriate. In the present embodiment, the CA fiber 61 can also be plasticized by adding water to the tow band 60. Further, by adding the moisture of the heated water to the tow band 60, the CA fiber 61 can be plasticized by both the moisture and the heating. Thereby, by forming the short fiber 62 of a uniform length dimension, the nonwoven fabric 63 can be efficiently manufactured.

[0081] (Confirmation Test)

[0082] Next, the confirmation test will be described, but the present disclosure is not limited to the examples shown below. The short fibers of Examples 1 to 3 and Comparative Examples 1 and 2 were produced in the following order.

[0083] [Production of Example 1]

[0084] The tow band 60 in which the TD was set to 30000, the FD was set to 3 346 per 1 inch in length (the number of crimps once) was used. The number of crimps of the tow band 60 was counted in the following method. The sampled tow band 60 was placed on a workbench, one end of the direction in which the tow band 60 was crimped and relaxed was fixed to the side of the workbench, and the other end was vertically lowered from one end of the workbench. By applying a certain load to the other end of the tow band 60 by a weight, a certain tension was given to the tow band 60 in the direction in which the tow band 60 was crimped and relaxed. In this state, the concave-convex present on the surface of the tow band 60 was made to appear by illumination. Then, the surface of the tow band 60 was photographed by an optical sensor such as a CCD (Charge Coupled Device) camera.

[0085] The captured image is binarized by the following method. For the pixel value (as an example, luminance) of each pixel in the captured image, if it is equal to or greater than a predetermined threshold value, the computer is caused to convert it to "1", and if it is less than the threshold value, the computer is caused to convert it to "0". Next, in the case where a pixel group in which pixels having the pixel value "1" exist continuously in a prescribed form in the direction in which the tow band 60 is stretched and shrunk is present in the image obtained by the conversion, the computer is caused to determine that the pixel group is a mountain portion. Further, in the case where a pixel group in which pixels having the pixel value "0" exist continuously in the prescribed form in the direction is present in the image obtained by the conversion, the computer is caused to determine that the pixel group is a valley portion. Further, the computer is caused to count the number of the mountain portions and the valley portions obtained by dividing the total number of the mountain portions and the valley portions by 2. Thus, the number of the shrinks (the number of shrinks per 1 inch) of the tow band 60 in the direction is counted.

[0086] Further, the tow band 60 is introduced into the nonwoven fabric manufacturing apparatus 1, and the entangling relaxation step and the short fiber forming step disclosed in the first embodiment are performed. In the entangling relaxation step, the tension imparted to the tow band 60 in the transport direction P is set so that the entire tow band 60 is 0.3 kgf (10 mgf per 1 denier). Further, moisture is added to the tow band 60 by spraying heated steam (100°C or higher) from the nozzle 22. In the entangling relaxation step, the amount of moisture of the tow band 60 is adjusted so that the amount of moisture of the tow band 60 immediately before being cut in the short fiber forming step is 10.8 mass%. Further, in the short fiber forming step, the tow band 60 is cut to the target size 51 mm by the cutting mechanism 30 having the guillotine type cutter.

[0087] [Production of Example 2]

[0088] Further, the tow band 60 is introduced into the nonwoven fabric manufacturing apparatus 1, and the entangling relaxation step and the short fiber forming step disclosed in the first embodiment are performed. In the entangling relaxation step, the tension imparted to the tow band 60 in the transport direction P is set so that the entire tow band 60 is 0.3 kgf (10 mgf per 1 denier). Further, moisture is added to the tow band 60 by spraying heated steam (100°C or higher) from the nozzle 22. In the entangling relaxation step, the amount of moisture of the tow band 60 is adjusted so that the amount of moisture of the tow band 60 immediately before being cut in the short fiber forming step is 10.8 mass%. Further, in the short fiber forming step, the tow band 60 is cut to the target size 51 mm by the cutting mechanism 30 having the guillotine type cutter.

[0089] [Production of Example 3]

[0090] The same tow band 60 as in Example 1 was introduced into the nonwoven fabric manufacturing apparatus 11, and the entanglement relaxation step and the short fiber forming step were performed by the method disclosed in the third embodiment. In the entanglement relaxation step, the tension imparted to the tow band 60 in the transport direction P was set so that the entire tow band 60 was 0.3 kgf (10 mgf per 1 denier). In the entanglement relaxation step, the moisture content of the tow band 60 was adjusted so that the moisture content of the tow band 60 immediately before being cut in the short fiber forming step was 68.4 mass%. In the short fiber forming step, the tow band 60 was cut to the target size 51 mm by the cutting mechanism 30 having a guillotine-type cutter.

[0091] [Production of Comparative Examples 1 and 2]

[0092] The short fibers of Comparative Examples 1 and 2 were formed by the same method as in Example 1 except that an opening step was performed instead of the entanglement relaxation step, the opening step being a step in which, with respect to a tow band being transported in a predetermined transport direction, the tow band is opened by a plurality of opening rollers arranged separately in the transport direction, and tension is applied to the tow band in the transport direction and the width direction. In Comparative Example 1, a tow band having a crimp number per 1 inch in length (primary crimp number) of 340 before opening was used. In Comparative Example 2, a tow band having a crimp number per 1 inch in length (primary crimp number) of 310 before opening was used.

[0093] With respect to each of the short fibers of Examples 1 to 3 and Comparative Examples 1 and 2 produced as described above, the state when carding was performed, the presence or absence of clogging of the transport path of the short fibers in the short fiber manufacturing apparatus, the uniformity of the length dimension of the short fibers, and the tactile sensation of the short fibers were evaluated. The results of each evaluation and the test results are shown in Tables 1 and 2. Figure 4 is a photograph taken of the tow band 60 immediately after the entanglement relaxation of Example 1. Figure 5 is a photograph taken of the tow band 60 immediately after the entanglement relaxation of Example 2.

[0094] [Table 1]

[0095]

[0096] [Table 2]

[0097] Comparative Example 1 Comparative Example 2 TD 30000 30000 FD 3 3 Addition of moisture to the tow band None None Amount of moisture of the tow band before cutting Equilibrium moisture amount (6.5 mass%) Equilibrium moisture amount (6.5 mass%) Number of crimps of the tow band before the opening treatment 346 310 Number of crimps of the tow band after the opening treatment 346 310 Condition of the carding treatment With hooks With hooks Blocking of the short fibers in the conveyance path Yes Yes Form of the knife Gate type Gate type Uniformity of the length dimension of the short fibers Not uniform Not uniform Tactile feeling of the short fibers (not tacky) Good Good

[0098] As shown in Table 2, in Comparative Examples 1 and 2, a failure of short fibers hooking (entangling) to the carding machine occurred at the time of carding processing. In addition, the tow band of Comparative Example 1 was fluffy and elastic. In addition, the tow band of Comparative Example 2 also had the same fluffiness and elasticity as Comparative Example 1. Therefore, in Comparative Examples 1 and 2, it was difficult to introduce the tow band into the short fiber forming section 3. In addition, in Comparative Examples 1 and 2, the posture of the CA fiber with respect to the knife at the time of cutting the tow band by the cutting mechanism 30 was unstable compared to Examples 1 to 3. Therefore, in Comparative Examples 1 and 2, the length dimension of the short fibers had a large unevenness.

[0099] As shown in Table 1, Figure 4 and Figure 5 On the other hand, as shown in Table 1, in Examples 1 to 3, it was confirmed that the crimp number of the tow band 60 after moisture was added was slightly lower than the crimp number of the tow band 60 before moisture was added, but the crimp number of the tow band 60 was substantially maintained within a range where there was no problem. In addition, in Examples 1 to 3, it was confirmed that the entanglement of the CA fiber 61 in the tow band 60 was well slowed down by adding moisture to the tow band 60. In addition, in Example 1, it was confirmed that the CA fiber 61 in the tow band 60 was plasticized by the heated steam, and the slowing down of the entanglement of the CA fiber 61 in the tow band 60 was promoted. In addition, in Examples 1 to 3, it was confirmed that the carding processing of the plurality of short fibers 62 was well performed, and a failure in which the short fibers 62 were clogged in the conveyance path 50 or the like did not occur. In addition, when Examples 1 to 3 were compared with Comparative Examples 1 and 2, it was confirmed that the length dimension of the short fibers 62 was stabilized.

[0100] In addition, the moisture amount of the tow band 60 immediately before cutting in Example 1 was 10.8 mass%, and the moisture amount of the tow band 60 immediately before cutting in Example 2 was 28 mass%. In the short fibers 62 of Examples 1 and 2, a sticky feeling, appearance was not confirmed. In addition, in Examples 1 and 2, there was no need for the work amount of drying the tow band 60 that passed through the entanglement slowing section 2 and passed through the short fiber forming section 3. In addition, in Examples 1 and 2, a conspicuous failure due to the addition of moisture to the tow band 60 was not confirmed. In Example 3, the moisture addition amount to the tow band 60 before cutting was reduced to some extent. Therefore, in the short fibers 62 of Example 3, a degree of stickiness to water was not confirmed. Thus, the superiority of Examples 1 to 3 over Comparative Examples 1 and 2 was confirmed.

[0101] Each of the configurations and methods in each of the embodiments and combinations thereof and the like is one example, and additional, omission, substitution, and other changes of the configuration can be appropriately made within a range not departing from the gist of the present disclosure. The present disclosure is not limited by the embodiments but is defined only by the claims. In addition, each of the schemes disclosed in the present specification can be combined with any of the other features disclosed in the present specification.

[0102] In the above-described embodiments, an example in which the short fibers 62 are used for the production of the nonwoven fabric 63 is shown, but the use of the short fibers 62 can be a use other than the production of the nonwoven fabric. Further, in the nonwoven fabric production apparatuses 1, 11, the entanglement mitigation section 2, 12 is not essential. That is, in the nonwoven fabric production apparatuses 1, 11, for example, the entanglement mitigation section 2, 12 can be omitted, and the tow band 60 containing the crimped CA fibers 61 and having the moisture attached thereto can be carried in from the outside and introduced into the short fiber forming section 3.

[0103] Further, in the first and second embodiments, the moisture is attached to the tow band 60 by spraying the mist M from the nozzle 22 toward the tow band 60 in the entanglement mitigation step. However, the method of attaching the moisture to the tow band 60 is not limited thereto. For example, the moisture can be attached to the tow band 60 by filling the mist M in the housing 20 and passing the tow band 60 through the inside of the housing 20 in the entanglement mitigation step.

[0104] Further, in the drying step, the tow band 60 can be dried by a method other than heating. As the method of drying the tow band 60, any of the following methods can be employed: a method of blowing a gas against the tow band 60 to blow off the moisture, a method of vibrating the tow band 60 to cause the moisture to fall off, a method of centrifugally separating the moisture from the tow band 60, a method of passing the tow band 60 between a pair of press rolls (compression rolls) supported by a shaft to squeeze out the moisture from the tow band 60, or a method of causing the tow band 60 to which a tension is imparted in the conveyance direction P to abut against an abutting member such as a rotating roll to draw the tow band 60, or the like.

[0105] Further, in the second and third embodiments, for example, the tow band 60 to which the moisture is attached in the entanglement mitigation step can be dehydrated before the short fiber forming step, and the amount of the moisture of the tow band 60 immediately before the cutting can be reduced to a certain degree. As the method of reducing the moisture of the tow band 60, any of the drying methods of the tow band 60 mentioned in the above-described drying step can be employed. Thereby, for example in the case where the rotary-type cutter 33 is used, by setting the amount of the moisture of the tow band 60 immediately before the cutting to a value in the range of, for example, 7 mass% or more and 10 mass% or less, the occurrence of the adverse conditions of the cutting mechanism 30, the maintenance work caused by the excessive moisture of the tow band 60 can be suppressed. Thereby, the short fibers 62 can be formed with higher production efficiency.

[0106] Explanation of Reference Numerals

[0107] M: mist;

[0108] P: conveyance direction;

[0109] 1, 11: nonwoven fabric production apparatus (short fiber production apparatus);

[0110] 2, 12: entangling relaxation section;

[0111] 3: staple fiber forming section;

[0112] 5: nonwoven fabric forming section;

[0113] 33: rotary cutter;

[0114] 60: tow band (tow);

[0115] 61: cellulose acetate fiber;

[0116] 62: staple fiber;

[0117] 63: nonwoven fabric.

Claims

1. A method for manufacturing short fibers, the method comprising: The entanglement reduction step involves applying tension to a tow of cellulose acetate fibers, containing coiled fibers and coated with moisture, being conveyed in a predetermined conveying direction, and heating the tow, thereby reducing the entanglement of the coiled cellulose acetate fibers in the tow; and The short fiber forming step involves cutting the entangled bundles to form short fibers.

2. The method for manufacturing short fibers according to claim 1, wherein, In the entanglement reduction step, moisture is added to the filament bundle in such a way that the moisture content of the filament bundle before it is about to be cut in the short fiber forming step is in the range of 7% by mass or more and 80% by mass or less.

3. The method for manufacturing short fibers according to claim 1, wherein, In the entanglement reduction step, the entanglement is reduced by heating the filament bundle, which has been coated with moisture such that the moisture content of the filament bundle before it is about to be cut in the short fiber formation step is greater than the equilibrium moisture content according to JIS L 1013:2010.

4. The method for manufacturing short fibers according to claim 1, wherein, In the entanglement mitigation step, the filament bundle is moistened by bringing a mist containing moisture into contact with it.

5. The method for manufacturing short fibers according to claim 4, wherein, The fog contains moisture vapor.

6. The method for manufacturing short fibers according to claim 5, wherein, In the entanglement reduction step, the mist is brought into contact with the filament bundle in such a way that the moisture content of the bundle before it is about to be cut in the short fiber forming step is in the range of 7% by mass or more and 15% by mass or less.

7. The method for manufacturing short fibers according to claim 4, wherein, In the entanglement reduction step, the mist is brought into contact with the filament bundle in such a way that the moisture content of the bundle before it is about to be cut in the short fiber forming step is in the range of 7% by mass or more and 35% by mass or less.

8. The method for manufacturing short fibers according to any one of claims 1 to 7, wherein, After the short fiber forming step, there is a drying step to dry the moisture adhering to the short fibers.

9. The method for manufacturing short fibers according to any one of claims 1 to 7, wherein, In the short fiber forming step, the filament bundle is cut by a rotary cutter having a cutting edge disposed on the circumferential surface and supported by an axis, and is driven to rotate in such a way that the filament bundle comes into contact with the cutting edge.

10. A method for manufacturing a nonwoven fabric, wherein, Nonwoven fabrics are manufactured using short fibers formed by the manufacturing method as described in any one of claims 1 to 9.

11. A short fiber manufacturing apparatus, the short fiber manufacturing apparatus comprising: An entanglement mitigation section applies tension to a tow of cellulose acetate fibers, which is contained in coils and coated with moisture and is being conveyed in a predetermined conveying direction, and heats the tow, thereby mitigating the entanglement of the coiled cellulose acetate fibers in the tow; and The short fiber forming section cuts the strands after the entanglement has been reduced to form short fibers.

12. A nonwoven fabric manufacturing apparatus, the nonwoven fabric manufacturing apparatus comprising: The short fiber manufacturing apparatus as described in claim 11; and The nonwoven fabric forming section uses the short fibers formed by the short fiber forming section to form a nonwoven fabric.

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