JP5300231B2 - Short fiber manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for producing a short fiber by which the short fiber without adhering to each other through fusion can be produced in good workability. <P>SOLUTION: The method for producing the short fiber includes an addition process for adding an oil solution to a long fiber bundle having &le;4 &mu;m average fiber diameter, a fixing process for fixing the entire fiber bundle by surrounding the same with a sheet-like material, a cutting process for cutting the fiber bundle in a state in which the sheet-like material exists outside of a cut area or a cutting process for cutting the fiber bundle so that the most distant parts from the cut sides of the sheet-like material are connected, though there are cut brakes, and a removing process for removing the sheet-like material. <P>COPYRIGHT: (C)2009,JPO&amp;INPIT

Description

  The present invention relates to a method for producing short fibers. In particular, the present invention relates to a method for producing short fibers by cutting long fibers having an average fiber diameter of 4 μm or less.

  Nonwoven fabrics containing ultrafine short fibers having an average fiber diameter of 4 μm or less are excellent in various properties such as filtration performance, flexibility, concealability, and wiping properties, and therefore can be suitably used. One method for producing such a nonwoven fabric containing ultrafine short fibers is a short fiber in which a resin component (island component) difficult to remove by this solution is dispersed in a resin component (sea component) that can be removed by a solution. (So-called sea-island short fibers) is used to form a fiber web containing sea-island short fibers by the card method or air array method, and then the fibers are entangled with each other by the action of a needle or a water stream. Then, a method of dissolving and removing the sea components of the sea-island short fibers with a solution is known.

  According to this method, it is possible to produce a non-woven fabric containing ultrafine short fibers. However, since the ultrafine short fibers are in a bundled state, in order to unravel the ultrafine short fiber bundles or to impart shape stability. In addition, it was necessary to apply a fluid flow such as a water flow. However, when the fluid flow is applied, there is a problem that the texture is deteriorated.

  Therefore, after removing the sea component of the sea-island type long fiber to make an ultrafine fiber bundle, it is cut into a desired length to make an ultrafine short fiber, and if a fiber web is formed by a wet method using this ultrafine short fiber, It was thought that a nonwoven fabric with excellent formation could be produced. However, when the ultra-fine long fiber bundle is cut, the ultra-short fibers are fused together, and it is difficult to produce a nonwoven fabric with excellent texture.

  For this reason, the applicant of the present application has proposed a method for producing ultrafine short fibers, in which an oil agent is applied to the ultrafine fiber bundles, and the ultrafine fiber bundles are fixed after being fixed with a sheet-like material such as a film (Patent Document 1).

JP 2003-119668 A (Claim 3, Claim 7, Paragraph Nos. 0033, 0050)

  According to this production method, since the ultrafine short fibers can be produced without fusing the ultrafine short fibers with each other, it was possible to produce a nonwoven fabric with excellent texture. However, when ultra-short fibers are produced by this method, the sheet-like material such as a film fixing the ultra-fine fiber bundle is also cut together, and the ultra-short fibers and the cut pieces of the sheet-like material are mixed. Therefore, it is necessary to remove the cut piece of the sheet-like material, which is very complicated.

  Then, this invention was made | formed in order to solve such a problem, and provides the manufacturing method of the short fiber which can manufacture the short fiber with which the fibers have not melt | fused with sufficient workability | operativity. With the goal.

The invention according to claim 1 of the present invention is based on the “fixing step of enclosing and fixing a part or all of a long fiber bundle with a sheet-like material, the sheet-like material being connected at least partially, and derived from the sheet-like material. A method for producing short fibers, comprising: a cutting step of cutting the long fiber bundle and the sheet-like material so as not to generate a cut piece to be removed; and a removing step of removing the sheet-like material.

The invention according to claim 2 of the present invention is characterized in that "the cutting step is a step of cutting the long fiber bundle and the sheet-like material in a state where the sheet-like material exists outside the cutting region, The manufacturing method of the short fiber of Claim 1. ".

The invention according to claim 3 of the present invention is characterized in that “the cutting step is a step of cutting the long fiber bundle and the sheet-like material so that the portion farthest from the cutting side of the sheet-like material is connected. The manufacturing method of the short fiber of Claim 1. ".

  The invention according to claim 4 of the present invention is “the method for producing short fibers according to claim 3, wherein a cut is formed in a portion farthest from the cut side of the sheet-like material”.

The invention according to claim 5 of the present invention is as follows: “The fixing step covers the long fiber bundle supported on the support sheet with the cover sheet, and the surface of the cover sheet on the side of the support sheet. At least a part is a step of fixing the long fiber bundle in a state of being positioned on the support sheet-like object side with respect to the surface of the support sheet-like object, and the cutting step is a support of the cover sheet-like object A portion of the support sheet-like surface located on the support sheet-like object side is connected to the surface of the support sheet-like object, and a cut is formed on the surface of the support sheet-like object. However, the short fiber manufacturing method according to claim 1, wherein the long fiber bundle and the covering sheet are cut into a state in which the support sheet is connected.

  The invention according to claim 6 of the present invention is as follows: "The portion of the support sheet-like material where the surface of the support sheet-like material is located closer to the support sheet-like material than the surface of the support sheet-like material is a long fiber. 6. The method for producing a short fiber according to claim 5, wherein the short fiber is present at both ends in a direction perpendicular to the length direction of the bundle.

  The invention according to claim 7 of the present invention is as follows: “The portion of the support sheet-like material where the support sheet-like surface is located closer to the support sheet-like side than the cover sheet-like surface of the support sheet is long fiber The method for producing a short fiber according to claim 5 or 6, wherein the short fiber is present at a position other than both ends in a direction orthogonal to the length direction of the bundle.

  The invention according to claim 8 of the present invention is “the method for producing short fibers according to claim 1, wherein the average fiber diameter of the long fibers is 4 μm or less”. is there.

  The invention according to claim 9 of the present invention is the method according to any one of claims 1 to 8, further comprising an applying step of applying an oil agent to the long fiber bundle before the fixing step. The manufacturing method of a short fiber. "

  The invention according to claim 10 of the present invention is as follows. "The method for producing short fibers according to any one of claims 1 to 9, wherein the cutting step is a step of cutting to a fiber length of 3 mm or less." . "

In the invention according to claim 1 of the present invention, the sheet-like material is connected at least in part, and the long fiber bundle and the sheet-like material are cut so as not to generate a cut piece derived from the sheet-like material . The sheet-like material can be easily removed after cutting the long fiber bundle, and the short fiber can be produced with good workability.

In the invention according to claim 2 of the present invention, the long fiber bundle and the sheet-like material are cut in a state where the sheet-like material exists outside the cutting region, and the sheet-like material is connected at least in the region outside the cutting region. Therefore, the sheet-like material can be easily removed, and the short fiber can be manufactured with good workability.

The invention according to claim 3 of the present invention cuts the long fiber bundle and the sheet-like material so that the portion farthest from the cutting side of the sheet-like material is connected, and the sheet- like material has at least a portion farthest from the cutting side. Since they are connected, the sheet-like material can be easily removed, and short fibers can be produced with good workability.

  In the invention according to claim 4 of the present invention, when the cut is in the portion farthest from the cutting side of the sheet-like material, the long fiber bundle can be surely cut to produce the short fiber.

The invention according to claim 5 of the present invention is simple because it uses two sheets of a support sheet and a coated sheet and covers and fixes the long fiber bundle with the coated sheet. A long fiber bundle can be fixed with a simple device configuration. Moreover, since the long fiber bundle and the covering sheet are cut in a state where both the covering sheet and the supporting sheet are connected, the supporting sheet and the covering sheet can be easily removed, and workability is improved. Short fibers can be manufactured well. Furthermore, since the long fiber bundle is cut to such an extent that the support sheet is cut, the long fiber bundle can be reliably cut to produce short fibers.

  In the invention according to claim 6 of the present invention, after cutting the long fiber bundle, both ends in the direction orthogonal to the length direction of the long fiber bundle, that is, both ends in the width direction of the coated sheet are not cut and connected. Since it can be removed by applying a force to both ends of the covering sheet, the cut portion of the covering sheet can be prevented from dancing and stably removed.

  In the invention according to claim 7 of the present invention, after cutting the long fiber bundle, other than both ends in the direction orthogonal to the length direction of the long fiber bundle (both ends in the width direction), that is, in the intermediate portion of the covering sheet There are places that are not cut and connected. Therefore, it can suppress that the cut location of a coating sheet dances, and can remove more stably.

  In the invention according to claim 8 of the present invention, even if the long fiber has an average fiber diameter of 4 μm or less, it can be cut with certainty to produce an ultra-short fiber.

  Since the invention according to claim 9 of the present invention further includes an application step of applying an oil agent to the long fiber bundle before the fixing step, it can absorb heat when cutting the long fiber bundle, Moreover, since a film can be formed between the long fibers, fusion of the short fibers can be efficiently prevented.

  In the invention according to the tenth aspect of the present invention, even if the fiber length is cut to 3 mm or less, it is easy to remove the sheet-like material, so that short fibers can be produced with good workability.

  In the method for producing short fibers of the present invention, first, a fixing step is performed in which a part or all of a long fiber bundle is surrounded and fixed by a sheet-like material. The long fiber bundle is fixed by surrounding the long fiber bundle with a sheet so that the long fiber bundle is not displaced during cutting. It may be fixed by encircling only a part of the circumference, but the entire circumference of the long fiber bundle is surrounded by a sheet so as to reliably prevent cutting failure and fusion due to deviation of the long fiber bundle during cutting. It is preferable to fix. FIGS. 1 to 4, 9, and 11 are schematic views in a cross section of the long fiber bundle in a state where the entire circumference of the long fiber bundle is surrounded and fixed by a sheet-like material. In FIG. 1, a single sheet-like material 2 surrounds and fixes the entire circumference of the long fiber bundle 1 with the sheet-like material 2, and one outer side of the long fiber bundle 1 (direction perpendicular to the length direction of the long fiber bundle 1) 2 is a state in which the sheet-like material 2 is overlapped only at one end portion, that is, one end portion in the width direction of the sheet-like material. FIG. 1 is surrounded and fixed by the sheet-like material 2 and is fixed to both outer sides of the long-fiber bundle 1 (both ends in the direction perpendicular to the length direction of the long-fiber bundle, that is, both ends in the width direction of the sheet-like material). FIG. 3 shows a state in which the sheet-like material 2 is overlapped, and FIG. 3 shows the two sheet-like materials 2 surrounding and fixing the entire circumference of the long fiber bundle 1 with the sheet-like material 2. Outside (both ends in the direction perpendicular to the length direction of the long fiber bundle, that is, the sheet-like material 4 is a state in which the sheet-like material 2 is overlapped on both ends in the direction, and FIG. There is no overlap of the sheet-like material 2 on the outside of the bundle 1 (both ends in the direction orthogonal to the length direction of the long fiber bundle, that is, both ends in the width direction of the sheet-like material).

Further, FIG. 9 shows that the entire circumference of the long fiber bundle 1 is surrounded and fixed by two sheets of a support sheet 2 s for supporting the long fiber bundle 1 and a covering sheet 2 c for covering the long fiber bundle 1. Then, on both outer sides of the long fiber bundle 1 (both ends in the direction orthogonal to the length direction of the long fiber bundle 1, that is, both ends in the width direction of the support sheet-like material 2s or the covering sheet-like material 2c) The coated sheet-like material 2c extends to the outside more than the material 2s. In FIG. 9, the portion of the covering sheet-like material 2 c that extends outward from the supporting sheet-like material 2 s (hereinafter sometimes referred to as “protruding portions ₂ p ₁ , ₂ p ₂ ”) is a boundary with the supporting sheet-like material 2 s. in bends, protrusions 2p _1, 2p ₂ support sheet surface 2fs of the covering sheet 2c is located on the opposite surface flush with the cover sheet side surface of the supporting sheet 2s. In FIG. 9, although the projecting portion 2p _1, 2p ₂ support all sheet surface is located on the opposite surface flush with the cover sheet side surface of the supporting sheet 2s, protrusion it 2p _1, part of the support sheet surface 2fs of 2p ₂ may be located on the opposite surface flush with the cover sheet side surface of the supporting sheet 2s, projecting portion 2p _1, 2p ₂ of the support sheet side surface portion of the 2fs or entirely cover sheet side of the opposite surface of the coating sheet side surface of the supporting sheet 2s (however, in all cases, the support sheet It may be located closer to the support sheet-like object than the surface of the cover sheet-like object of 2s), or a part or all of the support sheet-like object surface 2fs of the protruding portions 2p ₁ and 2p ₂ may be the support sheet object. Opposite surface of 2s coated sheet side surface Remote may be further positioned on the support sheet side, but as in FIG. 9, the projecting portion 2p _1, 2p ₂ support all sheet surface is coated sheet material of the support sheet 2s If it is located on the same plane as the surface opposite to the surface, it is the most preferable aspect because it is excellent in the transportability of the support sheet and the covering sheet, and the protruding portions 2p ₁ and 2p ₂ are not easily cut by the cutting process described later. . Further, in FIG. 9, the portion of the supporting sheet-like object 2 c on the supporting sheet-like object side surface 2 fs is located closer to the supporting sheet-like object side than the covering sheet-like object side surface of the supporting sheet-like object 2 s (projected in FIG. 9). Portions 2p ₁ , 2p ₂ ) are present at both ends in the direction perpendicular to the length direction of the long fiber bundle 1, that is, both ends in the width direction of the support sheet-like material 2s or the covering sheet-like material 2c. However, it may be only one end, or may be present in an intermediate portion between both ends in addition to one end, or in some cases, an intermediate portion between both ends. May only exist. However, if present at both ends, both ends in the width direction of the covering sheet 2c are not cut by the cutting process described later, and are in a connected state, applying force to both ends of the covering sheet, Since it can suppress that the cut location of a coating sheet dances and can remove stably, it exists at least at both ends.

Figure 11 is a support sheet 2s ₁ for supporting the long fiber bundle _{1 1,} long fiber bundle _{1 2} supporting support sheet 2s _2, the support sheet 2s ₃ for supporting the long-fiber bundle _{1 3,} and the length the fiber bundle _{1 1,} 1 2, ₁ by ₃ covering sheet 2c covering the respective long fiber bundle _{1 1,} 1 2, _{1 3} is fixed to surround the entire periphery, the long fiber bundles ₁ 1, _{1 2} both ends in the direction perpendicular to the 1 ₃ lengthwise, that is, at both ends in the width direction of the covering sheet 2c, towards the cover sheet 2c than the supporting sheet 2s ₁ and the support sheet 2s ₃ there in addition to only cover sheet 2c extending more to the outside is present, between the support sheet 2s ₁ and the support sheet 2s _2, and the support sheet 2s ₂ and the supporting sheet even while the object 2s _3, cover sheet 2c only are present. The support sheet-like material 2s ₁ , the support sheet-like material 2s ₂ and the support sheet-like material 2s ₃ have the same thickness, and the opposite surfaces of the covering sheet-like material side surface are located on the same plane.

A portion where the covering sheet-like material 2c extends further outward than the supporting sheet-like material 2s ₁ and the supporting sheet-like material 2s _{3 and} only the covering sheet-like material 2c exists (protruding portions 2p ₁ , 2p ₂ ) Is bent at the boundary between the support sheet 2s ₁ and the support sheet 2s _3, and the support sheet-like surface 2fs of the protruding portion 2p ₁ of the cover sheet 2c is the cover sheet of the support sheet 2s ₁ located on the opposite surface flush with Jo material surface, and the opposite surface of the coating sheet material 2c projecting portion 2p ₂ of the support sheet surface 2fs the covering sheet side surface of the supporting sheet 2s ₃ of Located in the same plane.

In addition, a portion where only the covering sheet 2c exists between the supporting sheet 2s ₁ and the supporting sheet 2s ₂ (hereinafter may be referred to as “concave portion 2d ₁ ”) is the supporting sheet 2s _1. The support sheet-like object 2s ₂ is bent at the boundary with the support sheet-like substance 2s _2, and the support sheet-like object-side surface 2fs of the recess 2d ₁ of the cover sheet-like substance 2c is covered with the support sheet-like substance 2s ₁ and the support sheet-like substance 2s ₂ . The opposite surface of the side surface is in the same plane.

Furthermore, a portion where only the covering sheet 2c exists between the supporting sheet 2s ₂ and the supporting sheet 2s ₃ (hereinafter, may be referred to as “concave portion 2d ₂ ”) is the supporting sheet 2s _2. The support sheet-like material 2s ₃ is bent at the boundary with the support sheet-like material 2s _3, and the support sheet-like material-side surface 2fs of the recess 2d ₂ of the cover sheet-like material 2c is covered with the support sheet-like material 2s ₂ and the support sheet-like material 2s ₃ . The opposite surface of the side surface is in the same plane.

Therefore, the protruding portion 2p ₁ , the recessed portion 2d ₁ , the recessed portion 2d ₂ and the protruding portion 2p ₂ of the covering sheet-like material 2c, the support sheet-like material side surface, the supporting sheet-like material 2s ₁ , the supporting sheet-like material 2s ₂ and the supporting sheet. The opposite surfaces of the surface of the sheet 2s _{3 on} the side of the covering sheet are on the same plane.

In FIG. 11, the protruding portions 2p ₁ of the covering sheet 2c, the concave portion 2d _1, recess 2d _2, a supporting sheet side surface of the projecting portion 2p _2, the support sheet 2s _1, the support sheet 2s ₂ and the surface opposite to the covering sheet side surface of the support sheet 2s ₃ are all located on the same plane, but the protruding portion 2p ₁ , the recess 2d ₁ , the recess 2d ₂ and the protrusion of the covering sheet 2c A part of the surface of the part 2p _{2 on} the side of the support sheet is located in the same plane as the surface opposite to the surface of the side of the cover sheet of the support sheet 2s ₁ , the support sheet 2s ₂ , and the support sheet 2s _3. Or a part or all of the protruding sheet 2c ₁ , the recessed part 2d ₁ , the recessed part 2d ₂ , and the protruding part 2p ₂ of the covering sheet-like object 2c side surface of the supporting sheet-like object 2s ₁ , Support sheet 2 _2, cover sheet side of the opposite surface of the coating sheet side surface of the supporting sheet 2s ₃ (however, in all cases, the support sheet 2s _1, the support sheet 2s _2, the support sheet The covering sheet-like object side surface of the covering sheet-like object 2s ₃ may be positioned on the support sheet-like object side, or the protruding portion 2p ₁ , the recessed portion 2d ₁ , the recessed portion 2d ₂ , and the protruding portion 2p of the covering sheet-like object 2c. some or all of the _second support sheet side surface, the support sheet 2s _1, the support sheet 2s _2, further support sheet than the opposite surface of the coating sheet side surface of the supporting sheet 2s ₃ Although it may be located on the side of the sheet-like object, as shown in FIG. 11, the entire support sheet-like object side surface of the protruding part 2p ₁ , the recessed part 2d ₁ , the recessed part 2d ₂ , and the protruding part 2p ₂ is the supporting sheet-like object 2s. _1, the support sheet 2s _2, the support When located on the opposite surface flush with the cover sheet side surface of the over preparative like material 2s _3, excellent transportability of the support sheet 2s _1, 2s _2, 2s ₃ and cover sheet 2c, In addition, the protruding portion 2p ₁ , the recessed portion 2d ₁ , the recessed portion 2d ₂ , and the protruding portion 2p ₂ are the most preferable mode because they are not easily cut by a cutting process described later.

Further, in FIG. 11, the support sheet surface 2fs support sheet 2s 1 of the covering sheet _2c, the support sheet 2s _2, than cover sheet side surface of the supporting sheet 2s ₃ The portions located on the side of the support sheet (projecting portions 2p ₁ , recessed portions 2d ₁ , recessed portions 2d ₂ , projecting portions 2p _{2 in} FIG. 11) are both ends in the direction perpendicular to the length direction of the long fiber bundle 1, that is, The covering sheet-like material 2c is present at two positions in the width direction and an intermediate portion between the both ends, but is present at one end in the width direction of the covering sheet-like material 2c and an intermediate portion between the both ends. It may be present only in an intermediate portion between both ends. In any case, the number of recesses in the intermediate portion between both ends does not have to be two as shown in FIG. 11, and may be one or three or more. In particular, as shown in FIG. 11, in addition to both ends of the covering sheet-like material, the supporting sheet-like surface of the covering sheet-like material is also more support sheet-like than the covering sheet-like surface of the supporting sheet material in the middle portion. If there is a portion located on the object side, after cutting the long fiber bundle, the intermediate portion of the covering sheet material is also cut in addition to both ends in the direction perpendicular to the length direction of the long fiber bundle (both ends in the width direction). In addition, since there are connected portions, it is preferable because the cut portion of the covering sheet can be prevented from dancing and can be removed more stably.

Further, the support sheet-like material 2s ₁ , the support sheet-like material 2s ₂ and the support sheet-like material 2s ₃ do not have to have the same thickness, and the support sheet-like material 2s ₁ , the support sheet-like material 2s ₂ and the support sheet-like material opposite surface of the coating sheet material surface of the 2s ₃ need not be located in the same plane.

The long fibers constituting the long fiber bundle 1 are not particularly limited, but are thin fibers having an average fiber diameter of 4 μm or less that have been fused and difficult to cut by conventional methods. Even if it exists, it can cut | disconnect reliably and can manufacture a short fiber, without making it fuse | melt. In particular, even a long fiber having an average fiber diameter of 3 μm or less, and further an average fiber diameter of 2 μm or less, can be reliably cut to produce a short fiber without fusing. On the other hand, the lower limit of the average fiber diameter of the long fibers is an average fiber diameter that can be produced by the production method of the present invention, and is not particularly limited. Long fibers having an average fiber diameter of 4 μm or less (particularly fibers of 3 μm or less, fibers of 2 μm or less) can be obtained by removing sea components of sea-island long fibers with a solution. The “average fiber diameter” in the present invention refers to a value calculated from the following equation in consideration of the fiber density from the fineness measured by the vibration method described in JIS L 1015.
Average fiber diameter (μm) = {(D × 4) / (9000 × ρ × π)} ^(1/2) × 10 ³
Here, D means fineness (denier), and ρ means density (g / cm ³ ).

  In addition, although the constituent material of the long fiber is not particularly limited, in the production method of the present invention, it is cut without fusing even a synthetic long fiber that has a relatively low melting point and is easy to fuse, Short fibers can be produced. For example, a long fiber in which two or more kinds of polyamide fiber, polyolefin fiber, polyamide resin and / or polyolefin resin are combined or mixed (for example, a core-sheath type, a side-by-side type, a sea-island type, a multi-bimetal type in a cross section) , Orange-type long fibers, etc.) can be cut without fusing to produce short fibers. Of course, other short fibers can be produced by the production method of the present invention even if they are other synthetic long fibers having a high melting point, functional long fibers (for example, aramid long fibers), or inorganic long fibers such as glass long fibers. Can do.

  Further, the sheet-like material 2 (including the support sheet-like material 2s and the covering sheet-like material 2c, hereinafter the same) is not particularly limited as long as it can surround and fix the long fiber bundle 1, for example, A film, a nonwoven fabric, a woven fabric, paper, etc. can be mentioned. Among these, it is preferable that the film is less likely to generate scraps by cutting. In addition, since the sheet-like material 2 is in a connected state after the long fiber bundle 1 is cut and can be easily removed, the resin constituting the sheet-like material 2 is not particularly limited. In addition, the thickness of the sheet-like material is not particularly limited, but when cutting a long fiber bundle so as to make a cut at a portion farthest from the cutting side of the sheet-like material described later (for example, the support sheet-like material 2s) In the case of cutting a long fiber bundle with a slit, the sheet-like material is preferably 50 μm or more so that it can be easily cut in a connected state and the sheet-like material is not easily broken by handling after cutting. More preferably, it is 100 μm or more. The upper limit of the thickness is not particularly limited as long as the long fiber bundle can be cut.

  Such a fixing step can be carried out by a known method (for example, Japanese Patent Application Laid-Open No. 2003-119661). Further, when a long fiber bundle is fixed by the support sheet-like material 2s and the covering sheet-like material 2c, after supplying the long fiber bundle to be placed on the fed support sheet-like material 2s, the support sheet-like material is supplied. The coated sheet-like product 2c having a width wider than that of the product 2s can be supplied by coating so as to coat the long fiber bundle. In this case, the covering sheet is arranged such that at least a part of the surface of the covering sheet 2c on the side of the supporting sheet is surely positioned closer to the supporting sheet than the surface of the supporting sheet 2s. After covering the long fiber bundle with the material 2c, it is preferable to pressurize with a pair of rolls or the like. As described above, when the long fiber bundle is fixed by the support sheet-like material 2s and the covering sheet-like material 2c, the long fiber bundle can be fixed by a simple apparatus configuration.

  Subsequently, the cutting process which cut | disconnects a long-fiber bundle is implemented so that the sheet-like thing may be connected with at least one part, and the cut piece originating in a sheet-like thing may not be generated. As one of the cutting steps, there is a step of cutting the long fiber bundle in a state where the sheet-like material exists outside the cutting region (the region where the cutting blade or the like acts). For example, when the long fiber bundle 1 is fixed with the sheet-like material 2 as shown in FIG. 1, it is cut by the cutting blade 3 or the like as shown in FIG. The long fiber bundle 1 and the sheet-like material 2 can be cut by the cutting blade 3 or the like so that the sheet-like material 2 is also present on one outer side of the cutting region C. In this case, the sheet-like material 2 is also present in the non-cutting region R that is not cut by the cutting blade 3 or the like, so that even after the long fiber bundle 1 is cut, a part of the sheet-like material 2 (in the non-cutting region R). In the next step, the sheet-like material 2 can be easily removed because the cut portions derived from the sheet-like material 2 are not generated. Such cutting can be performed by a combination of a guillotine type fixed blade and a movable blade.

  FIG. 6 shows a schematic diagram in the cross-sectional direction of the long fiber bundle at the time of another cutting. In FIG. 6, after the long fiber bundle 1 is fixed with the sheet-like material 2 as shown in FIG. The long fiber bundle 1 and the sheet-like material 2 are cut by the cutting blade 3 or the like. Even in this case, since the sheet-like material 2 exists also in the non-cutting region R, even after the long fiber bundle 1 is cut, a part of the sheet-like material 2 (existed in the non-cutting region R). In the next step, the sheet-like material 2 can be easily removed because no cut pieces derived from the sheet-like material 2 are generated. Such cutting can be performed by a combination of a guillotine type fixed blade and a movable blade.

  Furthermore, the schematic diagram of the cross-sectional direction of the long fiber bundle at the time of another cutting | disconnection is shown in FIG. In FIG. 7, after the long fiber bundle 1 is fixed with the sheet-like material 2 as shown in FIG. The long fiber bundle 1 and the sheet-like material 2 are cut by the cutting blade 3 or the like. Even in this case, since the sheet-like material 2 exists also in the non-cutting region R, even after the long fiber bundle 1 is cut, a part of the sheet-like material 2 (existed in the non-cutting region R). In the next step, the sheet-like material 2 can be easily removed because no cut pieces derived from the sheet-like material 2 are generated. Such cutting can be performed by a combination of a guillotine type fixed blade and a movable blade.

  Further, FIG. 8 shows a schematic diagram in the cross-sectional direction of the long fiber bundle at the time of another cutting. In FIG. 8, the long fiber bundle 1 is fixed with the sheet-like material 2 as shown in FIG. 4 and then cut with the cutting blade 3 or the like, but the portion F farthest from the cutting side where the cutting blade 3 or the like is present is connected. In this manner, the long fiber bundle 1 is cut. Even in this case, a part of the sheet-like object 2 (part F farthest from the cutting side) is in a connected state, and no cut piece derived from the sheet-like object 2 is generated. The sheet-like material 2 can be removed. In addition, when cut | disconnecting so that the part F furthest from the cutting | disconnection side may be connected, the cutting blade 3 grade | etc., Cuts so that the cut | interruption B may enter into the sheet-like thing 2 (mode of FIG. 8) so that it may not enter. Although it can be cut, if the long fiber bundle 1 is cut so that the cut B enters, it is guaranteed that the cutting blade 3 and the like have reached the sheet-like material 2, so that the long fiber is surely The bundle 1 can be cut to produce short fibers, which is a preferred embodiment. Thus, in order to cut | disconnect so that the cut | interruption B may enter into the sheet-like article 2, it can implement with a half cut processing machine, for example. In addition, even when cutting the long fiber bundle 1 as shown in FIGS. 5 to 7, it can be cut so that the portion farthest from the cutting side is connected, and in particular, the sheet-like material is cut. Can be cut as follows.

Furthermore, the schematic diagram of the cross-sectional direction of the long fiber bundle at the time of another cutting | disconnection is shown in FIG. In FIG. 10, the long fiber bundle 1 is fixed with the support sheet 2s and the covering sheet 2c as shown in FIG. 9, and then cut with the cutting blade 3 or the like, but from the cutting side where the cutting blade 3 or the like is present. In this embodiment, the long fiber bundle 1 is cut so that the farthest portion F is connected. In this case, in the portion F farthest from the cutting side, both end portions in the width direction of the support sheet-like object 2s and the covering sheet-like object 2c are present, and the support sheet-like object side surface of the covering sheet-like object 2c is supported. The sheet 2s is located in the same plane as the surface opposite the coated sheet-like surface, so that the cutting blade 3 or the like has a cut B in the support sheet 2s, but the support sheet 2s is connected. Since the support sheet-like material 2s is in a connected state, the covering sheet-like material 2c is connected even though both ends (projection portions 2p ₁ , 2p ₂ ) have a break B. In this state, since no cut piece derived from the support sheet-like material 2s or the covering sheet-like material 2c is generated, the support sheet-like material 2s and the covering sheet-like material 2c can be easily removed in the next step. The In addition, since the long fiber bundle 1 is cut so that the cut B enters the support sheet-like material 2s, the long fiber bundle 1 can be cut reliably and the short fiber can be produced. Thus, in order to cut | disconnect so that the cut | interruption B may enter into the support sheet-like material 2s, it can implement with a half cut processing machine, for example. In addition, when making the cut | interruption B in 2 s of support sheet-like objects with the cutting blade 3 etc., it is necessary to consider in which position the support sheet-like object side surface of the covering sheet-like object 2c exists. That is, the depth of the cut B to be inserted into the support sheet-like material 2s is deeper than the surface of the support sheet-like material 2s on the cover sheet-like material side and shallower than the surface of the cover-sheet-like material 2c. However, a cut is made so that the support sheet 2s is connected and in a state). Depending on the depth of the cut, both end portions (projecting portions 2p ₁ and 2p ₂ ) of the covering sheet 2c may be cut (FIG. 10) or may not be cut.

Furthermore, the schematic diagram of the cross-sectional direction of the long fiber bundle at the time of another cutting | disconnection is shown in FIG. FIG. 12 shows a case in which long fiber bundles 1 ₁ , 1 ₂ , 1 ₃ are fixed with support sheet-like material 2 s ₁ , 2 s ₂ , 2 s ₃ and covering sheet-like material 2 c as shown in FIG. Although cut, the long fiber bundles 1 ₁ , 1 ₂ , and 1 ₃ are cut so that the portion F farthest from the cutting side where the cutting blade 3 or the like is present is connected. In this case, in the portion F farthest from the cutting side, the support sheet-like material 2s ₁ , 2s ₂ , 2s ₃ , both end portions in the width direction of the covering sheet-like material 2c (protruding portions 2p ₁ , 2p ₂ ), and the covering sheet The concave portions 2d ₁ and 2d ₂ of the sheet-like material 2c exist, the protruding portions 2p ₁ and 2p ₂ of the covering sheet-like material 2c, the support sheet-like material side surface of the covering sheet-like material 2c, and the concave portions 2d ₁ and 2d ₂ of the covering sheet-like material 2c Since the support sheet-like surface and the opposite surface of the support sheet-like surface of the support sheet-like materials 2s ₁ , 2s ₂ , 2s ₃ are located on the same plane, the cutting blade 3 etc. 2s ₁ , 2 s ₂ , 2 s ₃ , but when cut so that the respective support sheet-like materials 2 s ₁ , 2 s ₂ , 2 s ₃ are connected, the support sheet-like materials 2 s ₁ , 2 s ₂ , 2s state near _{the 3} led , Of course the, located in the cover sheet 2c also led in the both end portions (the protruding portion _2p 1, 2p ₂₎ and the recesses _2d 1, 2d ₂ states, each support sheet _{2s 1, 2s 2, 2s 3} In addition, since the cut pieces derived from the covering sheet-like material 2c are not generated, the supporting sheet-like materials 2s ₁ , 2s ₂ , 2s ₃ and the covering sheet-like material 2c can be easily removed in the next step. In order to cut the long fiber bundle 1 so that the cut B entering each supporting sheet _{2s 1,} 2s 2, 2s _3, and surely cut the long fiber bundle _{1 1,} 1 2, _{1 3,} short Fiber can be produced. To disconnect so that the cut B enters in this way each support sheet _{2s 1, 2s 2, 2s 3} , for example, can be carried out by the half-cut machine. In addition, when making the cut B in each support sheet-like material 2s ₁ , 2s ₂ , 2s ₃ with the cutting blade 3 or the like, the position of the support sheet-like material side surface of the covering sheet-like material 2c is considered. There is a need. That is, the depth of cut B Add to each support sheet _{2s 1, 2s 2, 2s 3} , deeper than the supporting sheet _{2s 1,} 2s 2, cover sheet side surface of the 2s _3, and the coating It is made shallower than the surface of the sheet-like material 2c on the side of the support sheet-like material (however, the support sheet-like materials 2s ₁ , 2s ₂ , and 2s ₃ are connected to form a cut). Depending on the depth of such a cut, there may be a cut in both ends (protruding portions 2p ₁ , 2p ₂ ) and the recesses 2d ₁ , 2d ₂ of the covering sheet 2c (FIG. 12). It may not be included.

  The cutting length of the long fiber bundle 1 in the cutting process as described above is not particularly limited, but conventionally, even if the fiber length is 3 mm or less, which requires a lot of labor to remove the sheet-like material 2. Since no cut piece is generated from the sheet-like material 2, the sheet-like material 2 can be easily removed, and short fibers can be produced with good workability. The lower limit of the cutting length is a length that can be cut, and is not particularly limited.

  And a short fiber can be manufactured by implementing the removal process which removes the sheet-like object 2. FIG. As described above, since the sheet-like material 2 is connected at least at a part and does not generate a cut piece derived from the sheet-like material 2, it can be easily removed. This removal process can be implemented by winding up the sheet-like object 2 with a winding roll, for example. In some cases, it can be removed by hand. In addition, after cutting the long fiber bundle, both ends in the direction orthogonal to the length direction of the long fiber bundle of the sheet-like material, that is, both ends in the width direction of the sheet-like material (including the covering sheet-like material) are connected. Then, force can be applied to both ends of the sheet-like material to prevent the cut portion of the sheet-like material from dancing, so that it can be removed stably. In particular, in addition to both ends in the width direction of the sheet-like material, when the intermediate portions at both ends are also connected, it is possible to prevent the cut portion of the sheet-like material from dancing, and thus it can be removed more stably.

  The above is a basic method for producing short fibers, but preferably further includes an applying step of applying an oil agent to the long fiber bundle 1 before the fixing step. By applying an oil agent to the long fiber bundle 1, heat at the time of cutting the long fiber bundle 1 can be absorbed, and a film can be formed between the long fibers, so that the short fibers can be fused efficiently. This is because it can be prevented. The effect of applying the oil agent is remarkable when the average fiber diameter of the long fibers is as small as 4 μm or less. Since this oil agent varies depending on the constituent material of the long fiber, it is not particularly limited. For example, a polyamide-based long fiber, a polyolefin-based long fiber, or a polyamide-based resin and / or a polyolefin-based resin are combined or mixed. In the case of long fibers, it preferably contains a polyether ester type nonionic activator. In consideration of dispersibility in the slurry when using short fibers, it is preferable to include an ether type nonionic activator in addition to the polyether ester type nonionic activator. When both the polyether ester type nonionic activator and the ether type nonionic activator are included, the mass ratio is preferably 1: 9 to 9: 1, and more preferably 2: 8 to 8: 2. The ratio is more preferably 3: 7 to 7: 3. If the amount of the ether type nonionic activator is too small, the fiber dispersibility tends to deteriorate in the slurry because it is difficult to penetrate into the long fiber bundle 1, and if the amount of the polyether ester type nonionic activator is too small, This is because they tend to be fused at the time of cutting. In addition, it is preferable that the density | concentration of an oil agent is 1-10 mass%, It is more preferable that it is 2-8 mass%, It is still more preferable that it is 3-6 mass%.

When such an oil agent is applied to the long fiber bundle 1, it is preferably applied so that the moisture content of the long fiber bundle 1 is 60% by mass or more, and 70% by mass or more so as to have excellent anti-fusing properties. It is more preferable to give so that it may become, and it is still more preferable to give so that it may become 80 mass% or more. The upper limit of the moisture content is an amount that the long fiber bundle 1 can hold, and is not particularly limited. This “moisture content” is calculated from the following equation in accordance with the moisture content measurement method described in JIS L 1015.
Moisture content (%) = (WW ′) / W ′ × 100
Here, W means a mass (g) after the oil agent is applied to the long fiber bundle 1, and W ′ means a mass (g) when the long fiber bundle 1 is completely dried.

  Examples of the method of applying the oil agent to the long fiber bundle 1 include a method of immersing the long fiber bundle 1 in an oil agent bath or a method of spraying the oil agent.

  Next, although the manufacturing method of the short fiber by this invention is demonstrated more concretely based on an Example, this invention is not limited to a following example.

Example 1
A long fiber bundle formed by dissolving and removing the sea components of the sea-island type fibers and converging polypropylene long fibers having an average fiber diameter of 2 μm to 100,000 dtex was formed. Next, this long fiber bundle was mixed with a polyether ester type nonionic active agent and an ether type nonionic active agent at a ratio of 1: 1, and then diluted with water to a concentration of 4.5% by mass in a mixed oil bath. And the excess mixed oil was squeezed out to make the moisture content of the long fiber bundle 70% by mass.

  Next, as shown in FIG. 3, the upper and lower portions of the long fiber bundle impregnated with the oil agent were sandwiched between two polyethylene films (thickness: 100 μm), and the entire periphery of the long fiber bundle was surrounded and fixed (the long fiber bundle Long sheet fibers are fed to the half-cut processing machine so that there is a film outside the cutting area, and a cut is made at the furthest part from the cutting side of the film. The bundle was cut into a fiber length of 2 mm to produce a short fiber. In addition, the film was connected in the area | region outside the cutting | disconnection area | region and the furthest part from the cutting | disconnection side, and the cut piece was not generate | occur | produced.

  Thereafter, two films in a partially connected state were removed by hand to produce short fibers. The film was in a connected state and could easily be removed.

  And after wet papermaking 70 mass% of these short fibers and 30 mass% of core-sheath type fibers (fiber diameter: 17.5 μm, fiber length: 10 mm) composed of separately prepared polypropylene (core) -polyethylene (sheath) The core-sheath fiber was fused by an oven set at a temperature of 138 ° C. to produce a nonwoven fabric. When the dispersion state of the short fibers in the obtained nonwoven fabric was observed with an electron microscope, the short fibers were not fused, and the texture was excellent.

(Example 2)
A polyester support film (thickness: 100 μm) having a width of 150 mm that acts as a support sheet is supplied and formed on the polyester support film in the same manner as in Example 1, and a long fiber bundle containing mixed oil (moisture content) Rate: 70% by mass) and a polyester-coated film having a width of 200 mm (thickness: 100 μm), which acts as a coated sheet, and after coating the long fiber bundle, Pressure was applied with a rubber roll, and the entire circumference of the long fiber bundle 1 was surrounded and fixed as shown in FIG. That is, the polyester-coated film has a protruding portion (protruding length: 25 mm) that extends outward from both sides of the polyester support film, and the protruding portion of the polyester-coated film is bent at the boundary with the polyester support film and protrudes. The polyester support film side surface of the part was located in the same plane as the opposite surface of the polyester support film side surface of the polyester support film.

  Next, the long fiber bundle fixed with the polyester support film and the polyester coated film is supplied to a half-cut processing machine, and the long fiber bundle is cut into a fiber length of 2 mm so that the polyester support film is cut. Manufactured. In addition, although the polyester support film has a cut, it is connected throughout the width direction and does not generate a cut piece, but the polyester coated film has a cut in the protruding part, but it is connected, so a cut piece is generated I did not.

  Thereafter, the polyester support film and the polyester-coated film were each removed by winding with a winding roll to produce short fibers. Since all the films were connected, they could be easily removed.

  And after wet papermaking 70 mass% of these short fibers and 30 mass% of core-sheath type fibers (fiber diameter: 17.5 μm, fiber length: 10 mm) composed of separately prepared polypropylene (core) -polyethylene (sheath) The core-sheath fiber was fused by an oven set at a temperature of 138 ° C. to produce a nonwoven fabric. When the dispersion state of the short fibers in the obtained nonwoven fabric was observed with an electron microscope, the short fibers were not fused, and the texture was excellent.

(Comparative example)
As shown in FIG. 4, a long fiber bundle containing the mixed oil (water content: 70% by mass) formed in the same manner as in Example 1 is surrounded by a single polyester film (thickness: 100 μm). (There is no film on both outside of the long fiber bundle), and then it is supplied to a guillotine cutting machine that combines a fixed blade and a moving blade, and the long fiber bundle and the film are completely cut to obtain a fiber length of 2 mm. Of short fibers were produced.

  Thereafter, the work of removing only the cut piece from the mixture of the short fiber and the cut piece of the film was performed manually, but it was a very complicated work requiring a great deal of labor.

Schematic diagram of the cross section of the long fiber bundle in a state where the entire circumference of the long fiber bundle is surrounded and fixed by a sheet-like material. Schematic diagram of the cross section of the long fiber bundle in a state where the entire circumference of the long fiber bundle is surrounded and fixed by a sheet-like material. Schematic diagram of the cross section of the long fiber bundle in a state where the entire circumference of the long fiber bundle is surrounded and fixed by a sheet-like material. Schematic diagram of the cross section of the long fiber bundle in a state where the entire circumference of the long fiber bundle is surrounded and fixed by a sheet-like material. Schematic diagram of cross-section direction of long fiber bundle during cutting Schematic diagram of cross-section direction of long fiber bundle during cutting Schematic diagram of cross-section direction of long fiber bundle during cutting Schematic diagram of cross-section direction of long fiber bundle during cutting Schematic diagram of the cross section of the long fiber bundle in a state where the entire circumference of the long fiber bundle is surrounded and fixed by the support sheet and the covering sheet. Schematic diagram of cross-section direction of long fiber bundle during cutting Schematic diagram of the cross section of the long fiber bundle in a state where the entire circumference of the long fiber bundle is surrounded and fixed by the support sheet and the covering sheet. Schematic diagram of cross-section direction of long fiber bundle during cutting

Explanation of symbols

1 long fiber bundle 1 ₁ , 1 ₂ , 1 ₃ long fiber bundle 2 sheet-like material 2c coated sheet-like material 2s support sheet-like material 2p ₁ , 2p ₂ protruding portion 2fs support sheet-like material side surface 2s ₁ , 2s ₂ , 2s ₃ Support sheet-like material 2d ₁ , 2d ₂ recess 3 Cutting blade C Cutting area R Non-cutting area F Farthest part B Cut line

Claims (10)

A fixing step of enclosing and fixing a part or all of the long fiber bundle with a sheet-like material, and the long fiber bundle so that the sheet-like material is connected at least partly and a cut piece derived from the sheet-like material is not generated. And a cutting step of cutting the sheet-like material , and a removing step of removing the sheet-like material. 2. The method for producing short fibers according to claim 1, wherein the cutting step is a step of cutting the long fiber bundle and the sheet-like material in a state where the sheet-like material exists outside the cutting region. The production of short fibers according to claim 1, wherein the cutting step is a step of cutting the long fiber bundle and the sheet-like material so that a portion farthest from the cutting side of the sheet-like material is connected. Method. The method for producing short fibers according to claim 3, wherein a cut is formed in a portion farthest from the cut side of the sheet-like material. The fixing step covers the long fiber bundle supported on the support sheet with the cover sheet, and at least a part of the surface of the cover sheet on the support sheet side covers the support sheet. It is a step of fixing the long fiber bundle in a state of being located closer to the support sheet-like object than the sheet-like object side surface, and the cutting step covers the support sheet-like object on the support sheet-like object surface. Although the portion located on the support sheet-like object side is connected to the sheet-like object side surface, and the cut is on the coated sheet-like object side surface of the support sheet-like object, the support sheet-like object is connected, The method for producing a short fiber according to claim 1, wherein the method is a step of cutting the long fiber bundle and the covering sheet . The portions where the support sheet-like surface of the cover sheet is located closer to the support sheet than the cover sheet-side surface of the support sheet are at both ends in the direction perpendicular to the length direction of the long fiber bundle. The method for producing a short fiber according to claim 5, wherein the short fiber is present. The portion where the support sheet-like surface of the cover sheet is located closer to the support sheet than the cover-sheet-side surface of the support sheet is other than both ends in the direction perpendicular to the length direction of the long fiber bundle. The method for producing a short fiber according to claim 5, wherein the short fiber is also present in the fiber. The method for producing a short fiber according to any one of claims 1 to 7, wherein an average fiber diameter of the long fibers is 4 µm or less. The method for producing short fibers according to any one of claims 1 to 8, further comprising an applying step of applying an oil agent to the long fiber bundle before the fixing step. The method for producing short fibers according to any one of claims 1 to 9, wherein the cutting step is a step of cutting to a fiber length of 3 mm or less.

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