absorbent articles

Abstract

The absorbent article (11) of the present invention has a front sheet (10) formed of a fibrous material and having a plurality of through holes (6), and a portion of the open end (6e) of the through hole (6) having a fiber orientation region (20) in which the fibers are oriented in one direction, and also having a fiber sheet disposed adjacent to the front sheet (10) on the non-skin-facing side. The fibers (21) in the front sheet (10) located in the fiber orientation region (20) engage with the constituent fibers of the fiber sheet. Preferably, the fiber sheet is a sublayer (15) disposed between the front sheet (10) and the absorbent (14), or a chip forming the surface of the absorbent (14).

Description

Technical Field

[0001] This invention relates to absorbent articles. Background Technology

[0002] Disposable diapers and other absorbent articles typically have a front sheet that contacts the wearer's skin on the skin-facing side of the liquid-retaining absorbent. Furthermore, in absorbent articles, it is common for a sheet component formed of fibers to be directly laminated onto the non-skin-facing side of the front sheet. For example, the applicant previously disclosed an absorbent article having a first nonwoven fabric and a second nonwoven fabric, with a front sheet having through holes formed at the welded portion where these two nonwoven fabrics are thermally fused together, and a liquid-permeable secondary layer laminated thereon, the welded portion having a protrusion extending into the secondary layer (Patent Document 1).

[0003] Existing technical documents

[0004] Patent documents

[0005] Patent Document 1: Japanese Patent Application Publication No. 2018-088997 Summary of the Invention

[0006] The present invention relates to an absorbent article having a front sheet and a fiber sheet formed of fibrous material.

[0007] The fiber sheet is preferably disposed adjacent to the front sheet on the non-skin-facing side of the front sheet.

[0008] Preferably, the front panel has a plurality of through holes, and a portion of the open end of the through hole has a fiber orientation region in which the fibers are oriented in one direction.

[0009] Preferably, the fibers in the fiber orientation region of the front sheet are engaged with the constituent fibers of the fiber sheet. Attached Figure Description

[0010] Figure 1 This is a schematic plan view of the unfolded and stretched skin-facing side (front panel side) of an unfolded disposable diaper, which is an embodiment of the absorbent article of the present invention.

[0011] Figure 2 It is a schematic representation Figure 1 Cross-sectional view of section II-II.

[0012] Figure 3 It is a schematic representation Figure 2 The plan view of the front panel is shown.

[0013] Figure 4 yes Figure 3 The cross-sectional view of the front panel along the longitudinal direction is shown.

[0014] Figure 5 yes Figure 3 The enlarged plan view of the through hole is shown.

[0015] Figure 6 It means Figure 4 A perspective view of the protrusions and through holes of the front panel shown.

[0016] Figure 7 yes Figure 2 The diagram shows a longitudinal cross-sectional view of the front panel and the secondary layer.

[0017] Figure 8 yes Figure 7 The diagram shows the three-dimensional representation of the secondary layer.

[0018] Figure 9 This is a schematic diagram showing one embodiment of a front sheet manufacturing apparatus.

[0019] Figure 10 It is Figure 9 A three-dimensional view showing the main part of the convex and concave roller (first roller) in an enlarged manner.

[0020] Figure 11 This is viewed from the upstream side of the conveying direction of the second piece. Figure 9 A front view showing the state of the main parts of the ultrasonic welding machine.

[0021] Figure 12 It means Figure 9 A diagram showing the main parts of the manufacturing apparatus (the front end of the ultrasonic welding head and its vicinity).

[0022] Figure 13 It is Figure 12 The enlarged cross-sectional view schematically shows the front end of the ultrasonic welding head along the direction orthogonal to the rotation axis (MD) of the convex and concave rollers.

[0023] Figure 14 yes Figure 12 The diagram shows a plan view of the vibration application surface (front end face) of the ultrasonic welding head.

[0024] Figure 15 This represents another embodiment of the ultrasonic welding head. Figure 13 The corresponding diagram.

[0025] Figure 16 This is another implementation method of ultrasonic welding head. Figure 13 The corresponding diagram.

[0026] Figure 17 This is another implementation method of ultrasonic welding head. Figure 13 The corresponding diagram.

[0027] Figure 18 (a) is another embodiment of the ultrasonic welding head. Figure 13 The corresponding diagram, Figure 18 (b) is to Figure 18 The diagram (a) shows the concave and convex portions and their vicinity, enlarged schematically. Detailed Implementation

[0028] The structure with multiple through-holes on the front sheet is effective in improving the permeability of urine and soft stool. However, if through-holes are provided on the front sheet, the contact area between the front sheet and the adjacent fiber sheet decreases, raising concerns about reduced adhesion between the front sheet and the fiber sheet. This could lead to positional shift of the front sheet, impairing wearing comfort. On the other hand, if the through-holes are reduced in size to address the aforementioned adhesion issue, there is a concern that the permeability of excrement may be compromised. The absorbent article described in Patent Document 1 offers improvements in maintaining excrement permeability and suppressing positional shift of the front sheet.

[0029] Therefore, the present invention relates to an absorbent article that maintains the permeability of excrement and inhibits the positional shift of the front sheet.

[0030] The present invention will now be described with reference to the accompanying drawings, based on its preferred embodiments. In the following drawings, the same or similar reference numerals are used to label the same or similar parts. The drawings are generally schematic illustrations, and the scale of various dimensions may differ from actual scale.

[0031] Figure 1 and Figure 2 The image shows an unfolded disposable diaper 11, representing one embodiment of the absorbent article of the present invention. The diaper 11 has a front panel 10 as described in the above embodiment. The diaper 11 has a longitudinal direction P corresponding to the wearer's front-back direction and a transverse direction Q orthogonal to it, and includes a liquid-retaining absorbent body 14 and a front panel 10 disposed on the side closer to the wearer's skin than the absorbent body 14.

[0032] Diaper 11 Figure 1 As shown, the diaper 11 has a crotch portion B located in the wearer's groin area, and a ventral portion A and a dorsal portion C extending forward and backward therefrom. The ventral portion A, crotch portion B, and dorsal portion C correspond to areas when the diaper 11 is divided into three equal parts along the longitudinal direction P. The crotch portion B has an excretory portion opposite to the wearer's penis, anus, or other excretory parts when the diaper 11 is worn; this excretory portion opposite is typically located at or near the center of the longitudinal direction P of the diaper 11. The longitudinal direction P corresponds to the direction extending from the ventral portion A of the diaper 11 through the crotch portion B towards the dorsal portion C.

[0033] In diaper 11, such as Figure 2As shown, the front sheet 10, the liquid-permeable sublayer 15, and the liquid-retaining absorbent 14 are layered sequentially from closest to furthest from the wearer's skin. More specifically, the diaper 11 has: an absorbent 14 as its main absorbent part; a front sheet 10 disposed on the skin-facing side of the absorbent 14 and overlapping the absorbent 14 at a position closer to the wearer's skin than the absorbent 14; a back sheet 13 disposed on the non-skin-facing side of the absorbent 14 and overlapping the absorbent 14 at a position farther from the wearer's skin than the absorbent 14; and a sublayer 15 disposed between the front sheet 10 and the absorbent 14.

[0034] In this specification, "skin-facing side" refers to the side of an absorbent article or its constituent parts (e.g., absorbent core) that faces the wearer's skin when the absorbent article is worn, i.e., the side relatively close to the wearer's skin. "Non-skin-facing side" refers to the side of an absorbent article or its constituent parts that faces the opposite side (clothing side) to the skin when the absorbent article is worn, i.e., the side relatively far from the wearer's skin. Furthermore, "when wearing" as used herein refers to maintaining the usual proper wearing position and does not include situations where the absorbent article is deviated from the proper wearing position.

[0035] The front sheet 10 and the back sheet 13 each have a larger size than the sublayer 15 and the absorber 14 disposed between the two sheets 10 and 13, such as Figure 1 The shape of the diaper 11 in its unfolded and elongated state is shown.

[0036] The absorbent body 14 has a relatively long shape in the longitudinal direction P, extending from the ventral side A to the dorsal side C. The absorbent body 14 includes a liquid-retaining absorbent core 140 and a coating layer 141 covering the outer surface of the absorbent core 140. The absorbent core 140 is typically formed from a fiber aggregate mainly composed of hydrophilic fibers such as wood pulp, and can be a structure in which the fiber aggregate or sheet carries absorbent polymer particles. The coating layer 141 is typically formed from paper, nonwoven fabric, or the like.

[0037] As the backing sheet 13, various sheets that have been used in such absorbent articles can be used without particular restrictions, such as resin films, laminates of resin films and non-woven fabrics, etc.

[0038] The diaper 11 of this embodiment has a secondary layer 15 as a fiber sheet disposed adjacent to the front sheet 10. The secondary layer 15 is disposed on the non-skin-facing side of the front sheet 10 and is a structure that performs functions such as improving the permeability of liquid from the front sheet 10 to the absorbent 14 and reducing the backflow of liquid absorbed by the absorbent 14 to the front sheet 10, and covers approximately the entire area of ​​the skin-facing side of the absorbent 14.

[0039] The front sheet 10, the secondary layer 15, the absorbent 14 (absorbent core 140, chip 141) and the back sheet 13 are joined together by known bonding methods such as adhesives.

[0040] like Figure 1 and Figure 2 As shown, the diaper 11 has a pair of leak-proof flaps 16, 16 disposed at both ends along the transverse direction Q of the absorbent body 14, which stand upright against the wearer's skin at least at the crotch B when the diaper 11 is worn. Each leak-proof flap 16 includes a liquid-resistant or water-repellent and breathable leak-proof sheet 160, one end of which is fixed to other components (e.g., front sheet, back sheet) as a fixed end, and the other end of which is a free end not fixed to other components. At the free end of the leak-proof sheet 160, the leak-proof flap is fixed in an elongated state in the longitudinal direction P by an elastic member 161, thereby being configured to be stretchable in that direction. When the diaper 11 is worn, the elastic member 161 contracts, causing the leak-proof sheet 160 to stand upright at least at the crotch B, with the fixed end serving as the upright base. This causes the pair of leak-proof flaps 16, 16 to stand up, thereby preventing urine and other excrement from flowing outward laterally Q. The leak-proof sheet 160 can be made of any material used for leak-proof flaps in absorbent articles without particular limitation. Preferably, it is made of a liquid-resistant or water-repellent and breathable material, such as a single or multiple layers of water-repellent nonwoven fabric, resin film, or laminated nonwoven fabric.

[0041] like Figure 1 As shown, between the leak-proof sheet 160 and the back sheet 13 located on the left and right sides of the wearer's legs, a linear elastic member 17 is fixed in an extended state along the longitudinal direction P, thereby forming a pair of leg folds when the diaper 11 is worn due to the contraction of the elastic member 17. The front sheet 10, the second layer 15, the back sheet 13, the absorbent body 14, the leak-proof sheet 160, and the elastic member 161 are joined together by known bonding methods such as hot-melt adhesives.

[0042] like Figure 1 As shown, a pair of hook and loop fasteners 18, 18 are provided on both sides of the back side C of the diaper 11 along the longitudinal direction P. A fastening portion consisting of the male side component of a mechanical fastener is attached to the hook and loop fastener 18. Furthermore, a fastening area 19 consisting of the female side component of a mechanical fastener is formed on the non-skin-facing side of the diaper 11's ventral side A. The fastening area 19 is formed by fastening the female side component of the mechanical fastener to the non-skin-facing side of the back panel 13, which forms the non-skin-facing side of the ventral side A, using known joining methods such as adhesives or heat sealing, thereby enabling the aforementioned fastening portion of the hook and loop fastener 18 to be detachably fastened.

[0043] exist Figures 3-6 The front sheet of this embodiment is shown in the figure. The front sheet 10 of this embodiment is a fiber sheet formed of fibrous material and has a plurality of through holes 6 through the sheet.

[0044] The front panel 10 has a laminated structure consisting of a first panel 1 and a second panel 2 made of fibrous material. These first panels 1 and second panels 2 are joined together via welded joints (not shown) that are fused together with each other.

[0045] The first sheet 1 and the second sheet 2 are composed of sheets made of fibrous material. For example, nonwoven fabric, woven fabric, and knitted fabric can be used as these sheets. From the viewpoint of skin feel, nonwoven fabric is preferred. The types of sheets constituting the first sheet 1 and the second sheet 2 can be the same or different.

[0046] Examples of nonwoven fabrics include hot-air nonwoven fabrics, spunbond nonwoven fabrics, spunlace nonwoven fabrics, meltblown nonwoven fabrics, resin-bonded nonwoven fabrics, and needle-punched nonwoven fabrics. Laminated products combining two or more of these nonwoven fabrics can also be used.

[0047] The preferred weights of the first piece 1 and the second piece 2 are 10g / m³. 2 The above, preferably 15g / m 2 The above is preferred, and 40g / m² is also preferred. 2 The following is more preferably 35g / m 2 Furthermore, 10 g / m² is preferred. 2 Above and 40g / m 2 The following is more preferably 15g / m 2 Above and 35g / m 2 the following.

[0048] As the fibers that make up nonwoven fabrics, fibers formed from various thermoplastic resins can be used.

[0049] Examples of thermoplastic resins include polyolefins such as polyethylene, polypropylene, and polybutene; polyesters such as polyethylene terephthalate and polybutylene terephthalate; polyamides such as nylon 6 and nylon 66; polyacrylic acid; polyalkyl methacrylate; polyvinyl chloride; and polyvinylidene chloride. These resins can be used alone or in mixtures of two or more. Furthermore, they can be used in the form of composite fibers, such as core-sheath type or side-by-side type.

[0050] The front panel 10 of this embodiment is as follows: Figure 3 As shown, a plurality of protrusions 5 protrude toward one side of the front panel 10 at the location adjacent to the through hole 6. Specifically, as... Figure 4 As shown, at least a portion of the portion other than the through hole 6 in the first piece 1 is formed with a plurality of protrusions 5 protruding to the side opposite to the side of the second piece 2.

[0051] The protrusions 5 and the through holes 6 are arranged alternately in a row along the longitudinal direction P, and multiple rows of such rows are formed in the transverse direction Q, which is parallel to the surface of the front panel 10 and orthogonal to the longitudinal direction P. The protrusions 5 and the through holes 6 in adjacent rows are staggered along the longitudinal direction P, more specifically, staggered by half a pitch.

[0052] In this embodiment, the longitudinal direction P is parallel to the flow direction (mechanical direction, hereinafter also referred to as "MD") during the manufacturing of the front sheet 10, and the transverse direction Q is parallel to the direction orthogonal to the MD during the manufacturing of the front sheet 10 (hereinafter also referred to as "CD"). In addition, the rotation axes of the convex roller 31 (first roller) and the convex roller 32 (second roller), which will be described later, are parallel to CD and orthogonal to MD.

[0053] In this embodiment, the front sheet 10 has a plurality of recesses 3 on the side of the first sheet 1, which are sandwiched by protrusions 5 in both the P and Q directions, and a through hole 6 is formed at the bottom of each recess 3.

[0054] Viewed as a whole, the front panel 10 has a relatively large undulation on the surface of the first panel 1 side, which is composed of the aforementioned concave portion 3 and the aforementioned convex portion 5, while the surface of the second panel 2 side is flat or is a relatively flat surface with less undulation compared to the surface of the first panel 1 side.

[0055] In this embodiment, the front panel 10, when viewed from above, has a top-view shape in which the protrusion 5 and the through hole 6 are respectively longer in the longitudinal direction P (see reference). Figure 3 ).

[0056] Each through hole 6 has a shape that is longer in the longitudinal direction P, and more specifically, has a generally rectangular shape in plan view. The front panel 10 has a welded portion (not shown) along a portion of the opening end 6e of the through hole 6, where the first panel 1 and the second panel 2 are fused together. At this welded portion, the thermoplastic resin constituting the fibers of at least one of the first panel 1 and the second panel 2 is melted and cured, thereby joining the first panel 1 and the second panel 2.

[0057] When viewed from above, the front panel 10 has a fiber orientation region 20 in which the fibers are oriented in one direction at a portion of the opening end 6e of the through hole 6. The through hole 6 in this embodiment is as follows... Figure 5 As shown, a pair of fiber-oriented regions 20, 20 are located on both sides of the through hole 6 along the long side direction (longitudinal P). Alternatively, the front panel 10 may have a fiber-oriented region 20 on only one of the two sides along the long side direction of the through hole 6, or it may have a fiber-oriented region 20 on one or both of the two ends along the short side direction of the through hole 6.

[0058] The fiber orientation region 20 is a portion of the area along the opening end 6e of the through hole 6, in which the constituent fibers of the first sheet 1 and the second sheet 2 are not film-formed and maintain their fiber morphology. In the fiber orientation region 20, the fibers 21 located in this region 20 are located within the through hole 6. Hereinafter, "the fibers 21 located within the through hole 6 in the fiber orientation region 20" will also be referred to as "fibers 21 within the region".

[0059] In fiber orientation region 20, such as Figure 5 and Figure 6 As shown, the constituent fibers of the front sheet 10 are oriented in one direction. Specifically, in the fiber orientation region 20, the extension direction of the fibers 21 in each region is approximately the same. In this embodiment, the fibers 21 in the region are oriented at an angle relative to the long side direction (longitudinal P) of the through hole 6 when viewed from above (see reference). Figure 5 Furthermore, when viewing the front sheet 10 along its thickness direction, there are fibers within the fiber 21 in the region that are tilted at a certain angle relative to the main surface (planar direction) of the front sheet 10. More specifically, within the fiber 21 in the region, there are fibers oriented with their front ends facing the non-skin-facing side in the thickness direction of the front sheet 10.

[0060] There are no particular restrictions on the orientation direction of the fibers 21 within the fiber orientation region 20. For example, when viewed from above through the through hole 6, the fibers 21 within the region can be oriented along the longitudinal direction P toward the ventral side A, or along the longitudinal direction P toward the dorsal side C, or along the transverse direction Q. In addition, the fibers 21 within the region can also be oriented two-dimensionally on the main surface (planar direction) of the front sheet 10, or three-dimensionally oriented in the thickness direction of the front sheet 10.

[0061] For ease of explanation, in Figure 3 and Figure 4 The orientation state of fiber 21 within the illustrated area is not shown; the location of fiber orientation region 20 is shown.

[0062] As previously described, the front sheet 10 is adjacent to the secondary layer 15 disposed on its non-skin-facing side. In the stacked state of the front sheet 10 and the secondary layer 15, fibers 21 in the fiber orientation region 20 of the front sheet 10 engage (attach) with the constituent fibers of the secondary layer 15. In this embodiment, the through-hole 6 of the front sheet 10 overlaps with the protrusion 152 of the secondary layer 15, and the fibers 21 located in the fiber orientation region 20 engage with the fibers 153 located in the protrusion 152 (see reference). Figure 7 ).

[0063] In this way, the fibers 21 located in the fiber orientation region 20 engage with the constituent fibers of the fiber sheet arranged adjacent to the front sheet 10, such as the secondary layer 15, thereby firmly bonding the front sheet 10 to the fiber sheet and effectively suppressing the positional displacement of the front sheet 10. That is, even if the contact area between the front sheet 10 and the fiber sheet is reduced due to the formation of the through hole 6 in the front sheet 10, the bonding strength between the front sheet 10 and the fiber sheet is ensured by the engagement, so the permeability of excrement based on the through hole 6 can be maintained, and the positional displacement of the front sheet 10 can be suppressed.

[0064] The fiber orientation region 20 is the region in which the orientation directions of the fibers 21 located in the through hole 6 of the constituent fibers of the front sheet 10 are approximately the same, and can be determined by the following method.

[0065] [Methods for observing fiber orientation regions]

[0066] For the front plate 10, a 50mm × 50mm area is cut out from the top view using a sharp blade (e.g., a blade manufactured by FEATHER SAFETY RAZORCO.,LTD) as a sample. Then, using an electron microscope (e.g., JCM-6000Plus manufactured by Nippon Electron Co., Ltd.) or a microscope (e.g., VHX-1000 manufactured by KEYENCE CORPORATION), the through-hole 6 is observed from either the skin-facing side or the non-skin-facing side of the sample. If the front plate 10 has a protrusion 5 protruding towards either side, the through-hole 6 is observed from the side opposite to the protruding side of the protrusion 5. For example, if the protrusion 5 is formed on the skin-facing side of the front plate 10, the through-hole 6 is observed from the non-skin-facing side. The magnification for observing the through-hole 6 from this top view is 100x. A 3mm × 3mm area is photographed within the observation field. The obtained image is binarized. Specifically, the aforementioned image is captured in Image-Pro Plus (manufactured by Nippon Roper Co., Ltd.), and the black-and-white contrast is set to 100 by emphasizing contrast. Noise is removed by filtering (median, 5×5 times). In the image after this binarization process, the fibers located within the through-hole 6 are taken as the observation object. For each fiber of this observation object, the angle formed with the opening end 6e where the base end of the fiber is located is taken as the orientation angle, and this orientation angle is measured. The region where the leading ends of the fibers face approximately the same direction and the average value of the fiber orientation angle is within 0 to 60 degrees is determined and is taken as the fiber orientation region 20. In the part where the fiber orientation region 20 is located, the opening end 6e of the through-hole 6 becomes the boundary between the region where the fibers are oriented in one direction (fiber orientation region 20) and the region where the fibers are randomly oriented. The "region where the fibers are randomly oriented" is the region that has the same orientation state as the nonwoven fabric before the through-hole 6 is formed in the manufacturing method of the front sheet 10 described later. In addition, the "region where the fibers are randomly oriented" includes regions where the fiber orientation state cannot be determined due to fiber film formation, etc. Such areas are those regions observed as whitened areas in the binarized image where the degree of fiber orientation cannot be determined.

[0067] Alternatively, the front panel 10, along with the through-hole 6, can be cut along its long side by bisecting the short side of the through-hole 6. A binarized image of the cross-section can then be obtained using the same method as described above. In this image, the region where fibers with their front end (free end) facing the non-skin-facing side is located is identified and designated as the fiber orientation region 20. In this fiber orientation region 20, the fibers are inclined at a certain angle relative to the main surface (planar direction) of the front panel 10. Specifically, the fibers are configured such that the average angle between the fiber and the long side direction of the through-hole 6 (longitudinal P in this embodiment) is greater than 0 degrees and within 90 degrees.

[0068] When measuring the dimensions (length, angle, number of fibers present, etc.) of the fiber orientation region 20 and the fibers 21 within the region, the above observation methods can be applied unless otherwise specified.

[0069] The above-described method for observing the fiber orientation region is applicable to various nonwoven fabrics having the structure of the front sheet 10 of the present invention. More specifically, in the case where the front sheet 10 is a hot-air nonwoven fabric, the fiber orientation region 20 can be determined by the following method.

[0070] For the top view of the front sheet 10, a binarized image was obtained using the same method as described above for observing the fiber orientation region. When observing the through-hole 6 and its vicinity in this image, the membrane portion present within the through-hole 6 and the ventilation portion containing the constituent fibers that maintain the fiber shape can be identified. The constituent fibers that maintain the fiber shape cannot be observed in the membrane portion; these constituent fibers are molten portions, and their thickness is extremely small compared to the ventilation portion. The membrane portion is a membrane-like portion with a thickness of 50 μm or less. When the front sheet 10 is formed from hot-air nonwoven fabric, when the through-hole 6 is formed in the manufacturing method described later, the aforementioned membrane portion is formed in such a way that it extends from the opening end 6e of the through-hole 6 toward the inside of the through-hole 6. In the front sheet 10, there is a fiber protruding further toward the inside of the through-hole 6 from the membrane portion and having a free end therein; this fiber becomes the fiber 21 in the region, constituting the fiber orientation region 20. In the above image of the front sheet 10, the boundary between the membrane portion and the ventilation portion is taken as the opening end 6e of the through hole 6. Furthermore, the orientation of the fibers (fibers 21 within the region) constituting the fiber orientation region 20 in the front sheet 10 is represented by the angle formed by the opening end 6e (end edge of the through hole 6) located on the base end side of the fiber 21 and the imaginary line connecting the base end and free end of the fiber 21. This angle is an acute angle of 0 to 90 degrees. Regarding the fibers 21 within the region of the fiber orientation region 20, the average value of the angle formed by the opening end 6e (end edge of the through hole 6) located on the base end side of the fiber 21 and the aforementioned imaginary line is within 0 to 90 degrees. The base end of the fiber 21 within the region is the connection portion of the fiber 21 protruding from the membrane portion and connected to the membrane portion. In the front sheet 10 formed of hot-air nonwoven fabric, the fiber orientation region 20 has one or more fibers 21 within the region, preferably two or more.

[0071] When the front sheet 10 is formed of hot-air nonwoven fabric, the length of the film portion in the long side direction (P direction in this embodiment) of the through hole 6 is preferably 5 times or more and less than 450 times the thickness of the film portion. With this structure, the fibers 21 in the region can be more firmly engaged with the constituent fibers of the fiber sheet.

[0072] Based on the same viewpoint as above, the length of the membrane portion in the short side direction (Q direction in this embodiment) of the through hole 6 is preferably more than 5 times and less than 250 times the thickness of the membrane portion.

[0073] The structure of the fiber orientation region 20 and the front sheet 10 will be described in detail below. The following description is applicable to all nonwoven fabrics having the structure of the front sheet 10 of the present invention.

[0074] Whether the fibers constituting the fiber 21 located in the fiber orientation region 20 and the fiber sheet arranged adjacent to the front sheet 10 in the secondary layer 15, etc., are engaged can be confirmed by the following method.

[0075] From the diaper 11, the front sheet 10 and the adjacent fiber sheet are stacked, and a 50mm × 50mm sample is cut out in the thickness direction including the fiber orientation region 20 in the through hole 6. Next, the cross-section of the sample is observed at 100x magnification using an electron microscope (e.g., JCM-6000Plus, manufactured by Nippon Electron Ltd.) or a microscope (e.g., VHX-1000, manufactured by Keyence Corporation). In the field of view, if one or more fibers 21 located in the fiber orientation region 20 enter or intertwine with the constituent fibers of the fiber sheet, it is determined that the fiber 21 located in the fiber orientation region 20 is engaged with the constituent fibers of the fiber sheet. The position of the fiber sheet in which the fiber 21 is engaged with the constituent fibers in the fiber sheet is not particularly limited.

[0076] From the viewpoint of further improving the interlocking property with the fiber sheet of the secondary layer 15, the average length of the fiber 21 in the region is preferably 0.3 mm or more, more preferably 0.5 mm or more, and preferably 4 mm or less, more preferably 1.5 mm or less.

[0077] The average length of the fiber 21 within the region is measured using fibers that, in the field of view of the through-hole 6 from the opening end 6e of the through-hole 6 (i.e., from the base end to the free end), have a length of 0.2 mm or more. For example, when the front sheet 10 is formed of hot-air nonwoven fabric, the average length of the fiber 21 within the region is measured using the length from the base end protruding from the membrane portion to the free end. Measurements are performed on any 10 through-holes 6 in the front sheet 10, and their average is taken as the average length of the fiber 21 within the region.

[0078] Based on the same viewpoint as above, in the field of view of the through hole 6 when viewed from above, the number of fibers 21 in the region of one through hole 6 is 1 or more, preferably 2 or more, more preferably 5 or more, and preferably 20 or more. In addition, it is preferably 100 or less, more preferably 50 or less, and preferably 2 or more and 100 or less, more preferably 5 or more and 100 or less, and even more preferably 20 or more and 50 or less.

[0079] Furthermore, considering the same viewpoint as above, in the field of view of the through-hole 6 when viewed from above, each fixed field of view area (9mm²) of the fiber orientation region 20 2 The number of fibers 21 present in the region is preferably 1 or more, more preferably 5 or more, even more preferably 10 or more, and preferably 50 or less, more preferably 30 or less, and preferably 1 or more and 50 or less, more preferably 5 or more and 50 or less, and even more preferably 10 or more and 30 or less.

[0080] Based on the same viewpoint as above, within the area of ​​fiber 21 in one through hole 6, the number of fibers with their front ends facing the non-skin-facing side in the thickness direction of the front sheet 10 is preferably 1 or more, more preferably 20 or more, and preferably 100 or less, more preferably 50 or less, and preferably 1 or more and 100 or less, more preferably 20 or more and 100 or less.

[0081] Furthermore, considering the same viewpoint as above, each fixed field of view area (9mm) of the fiber orientation region 20 2 Within the area of ​​fiber 21, the number of fibers present facing the non-skin-facing side is preferably 1 or more, more preferably 10 or more, and preferably 50 or less, more preferably 30 or less.

[0082] The measurement of the number of fibers 21 or the number of fibers present in the aforementioned region is performed on any 10 through holes 6 containing fiber-oriented regions 20 in the front panel 10, and the average of these measurements is taken as the number of fibers 21 in the region of one through hole 6, or the number of fibers 21 in each fixed field of view (9mm²) of the fiber-oriented region 20. 2 The number of fibers 21 present within the region. A certain field of view area (9mm²) of the fiber orientation region 20. 2 ")" refers to a 3mm × 3mm area set at any position in the fiber orientation region 20 within the observation field of the through hole 6. The number of fibers 21 present within this region is counted, and the above-mentioned "fiber orientation region 20" is performed for each fixed field of view area (9mm²) of the fiber orientation region 20. 2 The measurement of the number of fibers 21 present in the region.

[0083] Furthermore, the "fibers facing the non-skin-facing side" can be determined by observing the cross-section of the front sheet 10 cut along with the through hole 6 in the above-mentioned [method for observing fiber orientation areas].

[0084] The front panel 10 has a fiber-oriented region 20 on a portion of the opening end 6e of the through-hole 6. From the viewpoint of further suppressing the aforementioned positional shift of the front panel 10, the length of the fiber-oriented region 20 along the opening end 6e of the through-hole 6, when viewed from above, is preferably 10% or more, more preferably 25% or more, and more preferably 60% or less, more preferably 50% or less, and more preferably 10% or more and 60% or less, more preferably 25% or more and 50% or less. The length of the fiber-oriented region 20 along the opening end 6e of the through-hole 6, and the entire circumference of the opening end 6e of the through-hole 6, can be measured by image processing of an electron microscope image of the through-hole 6. In such image processing, the multi-point distance measurement menu, which is installed by default in the software "KEYENCE VHX-1000", is used. For example, in an electron microscope image (magnification: 100x), the entire circumference of the opening end 6e can be measured by tracing the opening end 6e.

[0085] When the front panel 10 shifts towards the ventral side A of the longitudinal direction P, the discharged material will accumulate in the crotch area B and may leak. From the viewpoint of further suppressing such leakage, the fibers 21 located in the fiber orientation region 20 are preferably oriented along the longitudinal direction P (see reference). Figure 5 Therefore, the front panel 10 is less likely to shift towards the ventral side A, which can suppress the accumulation of stool in the crotch area B. "The fibers 21 in the region are oriented in the longitudinal direction P" means that more than 50% of the fibers 21 in the fiber orientation region 20 form an angle within ±45 degrees with the longitudinal direction P when viewed from above by the through hole 6. Since the long side direction of the through hole 6 in this embodiment is consistent with the longitudinal direction P, it can be determined whether "the fibers 21 in the region are oriented in the longitudinal direction P" based on whether the angle formed by the side of the through hole 6 along the long side direction of the through hole 6 and the fibers 21 in the region is within ±45 degrees.

[0086] From the viewpoint of further suppressing the offset of the front sheet 10 towards the ventral side A, the fibers 21 within the region are preferably oriented longitudinally P with their leading edges facing the ventral side A. Figure 5 In the illustrated embodiment, it is preferable that side A is the ventral side A and side B is the dorsal side C. Furthermore, taking... Figure 6 Taking the illustrated implementation as an example, side A is preferred. Figure 6 The left side) is the ventral side A, and the B side ( Figure 6 The right side) is the dorsal side C side.

[0087] In this embodiment, the front sheet 10 has fiber orientation regions 20 on both sides along the long side direction (longitudinal P) of the through hole 6. From the viewpoint of further suppressing the offset of the front sheet 10 in the longitudinal P, the angle θ (referring to the reference line La along the short side direction of the through hole 6) of the fibers located in the fiber orientation region 20, i.e., the fibers 21 within the region, relative to the reference line La along the short side direction of the through hole 6, is... Figure 5 The angle is preferably greater than 0 degrees, more preferably 30 degrees or more, further preferably 45 degrees or more, and also preferably less than 90 degrees, more preferably less than 80 degrees, and also preferably greater than 0 degrees and less than 90 degrees, more preferably 30 degrees or more and less than 90 degrees, and more preferably 45 degrees or more and less than 80 degrees. The reference line La is a straight line parallel to the short side of the through hole 6. The side of the through hole 6 is the portion of the opening end 6e (outline) of the through hole 6 along the long side direction of the through hole 6, while the short side is the portion of the rectangular through hole 6 outline that is adjacent to the side of the through hole 6 connected to the fiber 21 in the region and forms the short side.

[0088] The angle θ of fiber 21 within the region relative to the reference line La refers to the angle between the reference line La and the straight line connecting the two ends of fiber 21 within the region (the straight line connecting the free end and the base end). In the case where the end (base end) on the opposite side of the end (free end) located in the through hole 6 of the fiber being measured is not observed, the intersection of the fiber and the opening end 6e of the through hole 6 is taken as the end on the opposite side.

[0089] The fiber 21 within the region preferably has its front end (free end) facing the inside of the through hole 6. This structure allows for a more secure engagement with the fiber sheet adjacent to the front panel 10. In the above-described structure, for example, it is preferable that the front end of the fiber 21 within the region faces the inside of the through hole 6, and that the fiber 21 extends in a straight line.

[0090] From the viewpoint of further improving the permeability based on the through hole 6 and further suppressing the positional displacement of the front panel 10, the size of the through hole 6 is preferably within the following range.

[0091] The area ratio (area of ​​the through hole 6 / area of ​​the front sheet 10) of the through hole 6 in the front sheet 10 is preferably 4% or more, more preferably 8% or more, and even more preferably 30% or less, more preferably 20% or less, and even more preferably 4% or more and 30% or less, and even more preferably 8% or more and 20% or less.

[0092] The area of ​​each through hole 6 is preferably 1 mm². 2 The above, preferably 3mm 2 The above is also preferred, with 30mm being the ideal size. 2 The following is more preferably 20mm 2 The following is also preferred: 1mm 2Above and 30mm 2 The following is more preferably 3mm 2 Above and 20mm 2 the following.

[0093] The through hole 6 in this embodiment has a shape that is longer in the longitudinal direction P, but it may also have a shape that is longer in the transverse direction Q. Based on the same viewpoint as above, the size of the through hole 6 is preferably within the following range.

[0094] The length L6 of the longitudinal P of the through hole 6 is preferably more than 0.1 times, more preferably more than 1 times, and more preferably less than 5 times, more preferably less than 1.5 times, and more preferably more than 0.1 times and less than 5 times, and more preferably more than 1 times and less than 1.5 times.

[0095] The length L6 of the longitudinal P of the through hole 6 is preferably 1 mm or more, more preferably 1.5 mm or more, and also preferably 5 mm or less, more preferably 4.5 mm or less, and also preferably 1 mm or more and 5 mm or less, more preferably 1.5 mm or more and 4.5 mm or less.

[0096] The length W6 of the transverse Q of the through hole 6 is preferably 1 mm or more, more preferably 1.5 mm or more, and preferably 9 mm or less, more preferably 3 mm or less. It is also preferably 1 mm or more and 9 mm or less, and more preferably 1.5 mm or more and 3 mm or less.

[0097] The size of the through hole 6 is obtained by taking the average of the sizes (areas, etc.) of 10 randomly selected through holes 6 from any part of the measuring piece (10cm square) cut from the front panel 10.

[0098] From the viewpoint of further suppressing the positional displacement of the front sheet 10, the front sheet 10 is preferably a fiber located in the fiber orientation region 20 (fiber 21 within the region) with a smaller fiber diameter than other fibers due to partial melting on the outer side. Because such fiber 21 within the region has a smaller fiber diameter than other constituent fibers in the front sheet 10 and has an amorphous shape due to partial melting on the outer side, it is easier for it to intertwine with the constituent fibers of the fiber sheet that comes into contact with the fiber 21 within the region, thereby further improving the interlocking property between the fiber within the region and the constituent fibers.

[0099] Hereinafter, the "fibers with smaller diameters than other fibers that are partially melted on the outer side" in the fiber 21 within the region will also be referred to as "fine fibers 22 within the region".

[0100] The fine fibers 22 within the region can be identified by the following methods.

[0101] [Method for identifying fine fibers 22 within the region]

[0102] The through-hole 6, along with its surrounding portion, was cut out to include the fiber-oriented region 20, and this was used as a sample. Next, the sample was attached to the sample stage using double-sided paper tape (NiceTack NW-15 manufactured by NICHIBAN CO.,LTD.). Then, a platinum coating was applied to the sample. The coating was applied using an ion sputtering apparatus E-1030 (trade name) manufactured by Hitachi Naka Seiki Co., Ltd., with a sputtering time of 30 seconds. Next, the fiber-oriented region 20 in the sample was observed at 1000x magnification using an S-4000 field emission scanning electron microscope manufactured by Hitachi, Ltd., and the fine fibers 22 within the region were identified based on the difference in fiber diameter compared to the fibers located in the peripheral portion of the through-hole 6. During this observation, molten portions could be confirmed on the surface of the fine fibers 22 within the region. In particular, when the front sheet 10 contains core-sheath type composite fibers as its constituent fibers, these core-sheath type composite fibers readily become the fine fibers 22 within the region. In such a region, the fine fiber 22 becomes a state where the sheath component melts and the core component is exposed, thus its fiber diameter is smaller compared to other constituent fibers.

[0103] From the viewpoint that the fibers of the fiber sheet are more likely to intertwine, the fiber diameter of the fine fibers 22 in the region of the front sheet 10 is preferably 40% or more, more preferably 50% or more, and preferably 80% or less, more preferably 70% or less, and preferably 40% or more and 80% or less, more preferably 50% or more and 70% or less.

[0104] Based on the same viewpoint as above, the fiber diameter of the fine fibers 22 in the region of the front sheet 10 is preferably 3 μm or more, more preferably 4 μm or more, and even more preferably 7 μm or less, more preferably 6 μm or less, and even more preferably 3 μm or more and 7 μm or less, and even more preferably 4 μm or more and 6 μm or less.

[0105] The fiber diameter of the fine fibers 22 within the region is determined by observing the fine fibers 22 within the region using the same method as described in the [Method for Confirming Fine Fibers 22 within the Region], measuring the length of 10 fibers 22 in the width direction orthogonal to the long side direction, and taking the average value. Furthermore, the fiber diameter of the fibers located outside the fiber orientation region 20 is determined by selecting 10 fibers observed in the [Method for Confirming Fine Fibers 22 within the Region] located in the peripheral portion of the through-hole 6, and taking the average value of the length in the width direction relative to the long side direction of the selected fibers.

[0106] In a fiber orientation region 20, fine fibers 22 within the region and fibers 21 within the region with a larger fiber diameter than the fine fibers 22 within the region can coexist, or all fibers within the fiber orientation region 20 can be fine fibers 22 within the region.

[0107] From the viewpoint that the constituent fibers of the fiber sheet are more likely to intertwine, in the field of view of the through hole 6 when viewed from above, the number of fine fibers 22 in the region of one through hole 6 can be 1 or more, preferably 2 or more, more preferably 5 or more. It is also preferred to have 30 or less, more preferably 20 or less, and even more preferably 2 or more and 30 or less, more preferably 5 or more and 20 or less.

[0108] The fiber orientation region 20 can be formed in all the through holes 6 in the front sheet 10, or in a portion of the through holes 6.

[0109] From the viewpoint of further improving the permeability of excrement in the front sheet 10 and further suppressing the contact of excrement with the skin, the number of through holes 6 in the front sheet 10 with fiber-oriented regions 20 formed in a portion of the open end 6e is preferably 10% or more, more preferably 40% or more, and even more preferably fiber-oriented regions 20 are formed in all through holes 6.

[0110] Based on the same viewpoint as above, the number of through holes 6 in the front sheet 10 with fiber-oriented regions 20 formed in a portion of the opening end 6e is preferably 2 or more per unit area (area of ​​a 10mm square area when viewed from above). More preferably, it is 4 or more, and even more preferably 20 or less, and more preferably 15 or less.

[0111] From the viewpoint of skin feel and cushioning, the front sheet 10 of this embodiment preferably has the following structure.

[0112] The height H of the convex portion 5 (refer to Figure 4 The thickness is preferably 1 mm or more, more preferably 3 mm or more, and even more preferably 10 mm or less, more preferably 6 mm or less, and even more preferably 1 mm or more and 10 mm or less, and even more preferably 3 mm or more and 6 mm or less.

[0113] Each unit area (1cm²) in front of piece 10 2 The number of protrusions 5 is preferably 1 or more, more preferably 6 or more, and even more preferably 20 or less, more preferably 15 or less, and even more preferably 1 or more and 20 or less, and even more preferably 6 or more and 15 or less.

[0114] The bottom area of ​​the protrusion 5 is preferably 0.5 mm. 2 The above is preferred to be 2mm. 2 The above is also preferred, with 50mm being the ideal size. 2 The following is more preferably 20mm 2Alternatively, 0.5mm is preferred. 2 Above and 50mm 2 The following is more preferably 2mm 2 Above and 20mm 2 the following.

[0115] Next, the fiber sheet of the present invention will be described in detail.

[0116] In the diaper 11 of this embodiment, the fiber sheet disposed adjacent to the front sheet 10 is a secondary layer 15 disposed between the front sheet 10 and the absorbent body 14, but it is not limited thereto. For example, the fiber sheet may also be a ply 141 forming the surface of the absorbent body. In this case, the diaper 11 does not have a secondary layer 15, and the ply 141, which is a fiber sheet disposed adjacent to the front sheet 10, is used as such.

[0117] The fiber sheet disposed adjacent to the front sheet 10 has a structure with multiple recesses and protrusions, which makes it easier for the constituent fibers of the fiber sheet to intertwine with the fibers 21 in the region, and is preferred in terms of improving the engagement of the fiber orientation region 20. The secondary layer 15 of this embodiment has multiple recesses 151 and protrusions 152. Specifically, the secondary layer 15 has multiple protrusions 152 that protrude toward the skin-facing side and are hollow inside, and recesses 151 located between the multiple protrusions 152. These multiple recesses 151 and protrusions 152 are arranged alternately and continuously along the longitudinal direction P and the transverse direction Q. The secondary layer 15 has multiple protrusions 152 that protrude toward the skin-facing side and have an internal space S1, and recesses 151 located between the multiple protrusions 152, and multiple non-skin-facing protrusions 155 that protrude toward the non-skin-facing side and have an internal space S2, and non-skin-facing recesses 154 located between the multiple non-skin-facing protrusions 155 (see Figure 8 The uneven shape of the skin-facing side formed by the protrusions 152 and concave portions 151 in the secondary layer 15 corresponds to the uneven shape of the non-skin-facing side formed by the non-skin-facing protrusions 155 and non-skin-facing concave portions 154 in the same secondary layer 15. That is, in the non-skin-facing side of the secondary layer 15, a plurality of non-skin-facing concave portions 154 and non-skin-facing protrusions 155 are arranged alternately and continuously along the longitudinal direction P and the transverse direction Q. As a secondary layer 15 having such a structure, the intermediate sheet described in Japanese Patent Application Publication No. 2019-97678 can be used.

[0118] From the viewpoint of making it easier for the constituent fibers of the fiber sheet to intertwine with the fibers 21 within the region, a fiber sheet having multiple recesses and protrusions preferably has fibers located on the protrusions oriented in the longitudinal direction P. In such a structure, the fibers located on the protrusions form an angle within ±30 degrees with the longitudinal direction P. Furthermore, the fibers forming the surface of the protrusions that can contact the front sheet 10 are preferably oriented in the longitudinal direction P. That is, preferably, the fibers of the protrusions are oriented in the longitudinal direction P at one or more locations on the surface of the protrusions, at the top, at the bottom, and in the middle portion between the top and the bottom.

[0119] The orientation of the fibers in the protrusions of the fiber sheet, i.e., the angle between the fiber and the longitudinal direction P, can be confirmed by the following method. First, a measuring piece with a longitudinal length of 10 cm and a transverse length of 10 cm is cut from the fiber sheet. This measuring piece is cut in a manner that includes multiple protrusions. Next, the protrusions in the measuring piece are observed using a microscope (e.g., Keyence Corporation digital microscope VHX-1000) at a magnification of 60 to 200. This observation is performed on the protrusions formed on the side opposite to the front sheet 10. Next, for each arbitrary fiber observed within a certain observation area (e.g., 5 cm square), the two points where the fiber length is the largest within that area are determined. Next, the angle between the straight line connecting these two ends and the longitudinal direction P is measured. This measurement is performed on at least three observation areas, and the fiber orientation direction is obtained based on the arithmetic mean of the angles measured on a total of 30 or more fibers. In the measurement of fiber orientation, it is preferable to observe at a magnification that allows the identification of 10 or more fibers within the observation area.

[0120] From the viewpoint of facilitating contact between the fibers of the protrusions and the fibers 21 within the region, and further suppressing positional displacement of the front sheet 10, it is preferable that one or more protrusions in the fiber sheet overlap with the through-hole 6 of the front sheet 10. In this case, the protrusions and the through-hole 6 only need to overlap at least partially. In the secondary layer 15 of this embodiment, two or more protrusions 152 overlap with the through-hole 6 of the front sheet 10 (see reference). Figure 7 ).

[0121] From the viewpoint of further improving the above-mentioned effects, the dimensions of the protrusions 152 in the secondary layer 15 (fiber sheet) are preferably within the following range. The dimensions of the protrusions 152 are measured by microscopic observation of a cross-section of the secondary layer 15 in the thickness direction under no-load conditions.

[0122] The length L7 of the protrusion 152 on the longitudinal P (refer to) Figure 7 The length L6 of the through hole 6 on the longitudinal P (refer to) Figure 5Preferably, it is 50% or more, more preferably 100% or more, and further preferably 400% or less, more preferably 200% or less. It is also preferably 50% or more and 400% or less, more preferably 100% or more and 200% or less.

[0123] The length L7 of the protrusion 152 on the longitudinal P (refer to) Figure 7 The thickness is preferably 2mm or more, more preferably 4mm or more, and even more preferably 10mm or less, even more preferably 8mm or less. It is also preferred that the thickness is 2mm or more and 10mm or less, even more preferably 4mm or more and 8mm or less.

[0124] The height H1 of the convex portion 152 (refer to Figure 7 The thickness is preferably 1 mm or more, more preferably 3 mm or more, and even more preferably 10 mm or less, more preferably 6 mm or less, and even more preferably 1 mm or more and 10 mm or less, and even more preferably 3 mm or more and 6 mm or less.

[0125] In this embodiment of the diaper 11, on the skin-facing side of the secondary layer 15, the top of the protrusion 152 contacts the front sheet 10 (see reference). Figure 7 Furthermore, on the skin-facing surface of the aforementioned secondary layer 15, the recess 151 does not contact the front sheet 10. Thus, the secondary layer 15, on its skin-facing surface, has a skin-side contact portion that contacts the front sheet 10 and a skin-side non-contact portion that does not contact the front sheet 10. As previously described, on the skin-facing surface of the secondary layer 15, a plurality of recesses 151 and protrusions 152 are arranged alternately and continuously along the longitudinal direction P and the transverse direction Q, therefore the skin-side contact portions are arranged at intervals in both the longitudinal direction P and the transverse direction Q (see reference). Figure 8 ).

[0126] In this embodiment, the diaper 11, on the non-skin-facing side of the secondary layer 15, has its top of the non-skin-facing convex portion 155 in contact with the absorbent body 14 (see reference). Figure 7 Furthermore, on the non-skin-facing surface of the aforementioned secondary layer 15, the non-skin-side recess 154 does not contact the absorber 14. Thus, the secondary layer 15, on its non-skin-facing surface, has a non-skin-side contact portion that contacts the absorber 14 and a non-skin-side non-contact portion that does not contact the absorber 14. As described above, on the non-skin-facing surface of the secondary layer 15, a plurality of non-skin-side recesses 154 and non-skin-side protrusions 155 are arranged alternately and continuously along the longitudinal direction P and the transverse direction Q, therefore the non-skin-side contact portions are arranged at intervals in both the longitudinal direction P and the transverse direction Q.

[0127] In the secondary layer 15, each skin-side contact portion is preferably arranged to be surrounded by a skin-side non-contact portion (see reference). Figure 8According to this structure, a continuous space S2, which is the space of the recess 151 on the non-contact side of the skin, is formed in the planar direction, connecting with each other. This continuous space is effective in improving the diffusion of soft stool. The space S2 of the recess 151 is also the internal space S2 of the convex portion 155 on the non-contact side.

[0128] In the secondary layer 15, each non-skin-side contact portion is preferably arranged to be surrounded by a non-skin-side non-contact portion. Figure 8 (Refer to). According to this structure, a continuous space S1, which is the space of the non-skin side recess 154 that is the non-skin side non-contact portion, is formed in the planar direction, in which the spaces of the recesses S1 are connected to each other. This continuous space is also effective in improving the diffusion of soft stool. The space S1 of the non-skin side recess 154 is also the internal space S1 of the protrusion 152.

[0129] In each of the spaces S2 between the secondary layer 15 and the front sheet 10, and between the secondary layer 15 and the absorber 14, there are no gaps between the constituent fibers constituting the secondary layer 15. Specifically, there are no minute gaps with a fiber spacing of 0.01 mm to 0.2 mm.

[0130] From the viewpoint of further improving the diffusion of soft stool, when looking down at the sublayer 15 from the absorbent body 14 side which is the non-skin-facing side, the distance between adjacent non-skin-facing contact portions at the closest position is preferably 0.5 mm or more, more preferably 1 mm or more, and preferably 10 mm or less, more preferably 8 mm or less. It is also preferably 0.5 mm or more and 10 mm or less, more preferably 1 mm or more and 8 mm or less.

[0131] Based on the same viewpoint as above, when viewing the sublayer 15 from the front panel 10 side (which is the skin-facing side), the distance between adjacent skin-side contact portions at the closest positions is preferably within the same range as the distance between adjacent non-skin-side contact portions at the closest positions. The distance between adjacent skin-side contact portions and the distance between adjacent non-skin-side contact portions are measured by the following method.

[0132] First, a 50mm (lateral) × 50mm (longitudinal) sample is cut from the secondary layer 15 and used as the measurement specimen. Under no pressure, the sample is placed with the non-skin-facing side facing upwards. A transparent acrylic plate weighing 50g is placed on the sample, and a 700g weight is placed on the acrylic plate. A pressure of 30gf / cm² is applied. 2Under load, the surface shape of the sample was measured using a high-precision shape measurement system KS-1100 manufactured by Keyence Corporation. Measurement conditions included a measurement pitch of 50 μm, a movement speed of 10 cm / s, and a measurement area of ​​40 mm (CD direction) × 40 mm (MD direction) to obtain images. These images were then analyzed using the KS-Analyzer shape analysis application manufactured by Keyence Corporation to extract the locations of maximum thickness and locations with a thickness difference of less than 500 μm from the maximum thickness. These extracted areas were designated as non-skin-side contact areas. Additionally, areas outside the extracted areas (thickness differences exceeding 500 μm from the maximum thickness) were designated as non-skin-side non-contact areas. These non-skin-side contact and non-skin-side non-contact areas were then binarized. Specifically, the images were imported into Image-ProPlus (manufactured by Nippon Roper Co., Ltd.), and the black-and-white contrast was set to 100 by highlighting contrast. Noise was removed through filtering (median, 5×5, repeated 5 times). Next, for the binarized image, a line connecting the centroids of adjacent non-skin-side contact areas is drawn. The centroid of a non-skin-side contact area is the center of two points where a perpendicular line is drawn from the center of the Feret diameter of a non-skin-side contact area, intersecting the contact interface. A line connecting the closest centroids is drawn, and the distance between these lines is measured. This measured value is taken as the distance between adjacent non-skin-side contact areas.

[0133] The distance between adjacent skin-side contact points is measured by placing the test specimen with its skin-facing sides facing upwards, and then performing the same procedure as for the distance between adjacent non-skin-side contact points. 30 gf / cm² 2 The load-bearing capacity is the pressure (pressure resistance) applied to the back of the diaper when the infant is wearing a diaper 11 and is lying on his back.

[0134] As the fiber sheet of the second layer 15, a hydrophilic and liquid-permeable sheet can be used. Specifically, examples include paper, woven fabric, and nonwoven fabric. Nonwoven fabric is particularly preferred in terms of both high strength and excellent softness. The aforementioned nonwoven fabric can be used without particular limitations. From the viewpoint of easier entanglement with the fibers 21 in the region, the fiber sheet preferably contains hot-air nonwoven fabric. In this case, the fiber sheet can be composed of hot-air nonwoven fabric, or it can be a laminated nonwoven fabric composed of hot-air nonwoven fabric and other nonwoven fabrics.

[0135] The secondary layer 15 (fiber sheet) in this embodiment has a single-layer structure, but it can also be replaced by a multi-layer structure composed of multiple layers stacked together. Furthermore, the concave and convex shapes in the secondary layer 15 can be, for example, cone shapes such as cones, frustums of cones, pyramids, frustums of pyramids, or oblique cones. Examples of manufacturing methods for this secondary layer 15 include those described in Japanese Patent Application Publication Nos. 2013-133574, 2012-149370, and 2012-149371.

[0136] Next, the manufacturing method of the front sheet of the present invention will be described using the manufacturing method of the front sheet 10 of the above embodiment as an example. Figure 9 This describes a manufacturing apparatus 100 as one embodiment of the apparatus for manufacturing the front sheet of the present invention. The manufacturing apparatus 100 includes a contouring section 30 and an ultrasonic processing section 40.

[0137] The embossing section 30 includes an embossing roller 31 with an embossing surface. In the embossing section 30, a first piece 1 is made to follow the circumferential surface of the rotating embossing roller 31, thereby deforming the first piece 1 into an embossing shape along the embossing shape of the circumferential surface.

[0138] In addition to the convex-concave roller 31, the convex-concave shaping part 30 also has another convex-concave roller 32, which has concave and convex surfaces on its peripheral surface that engage with the concave and convex surfaces of the convex-concave roller 31.

[0139] Hereinafter, the concave-convex roller 31 will be referred to as the "first roller" and the concave-convex roller 32 will be referred to as the "second roller".

[0140] exist Figure 9 In the convex-concave shaping part 30 shown, two rollers 31 and 32 are used to rotate the two rollers 31 and 32 in such a way that the convex and concave parts of the two rollers 31 and 32 mesh with each other, and the first piece 1 is introduced into the meshing part 33, thereby deforming the first piece 1 into a convex-concave shape along the convex and concave shape of the peripheral surface of the convex and concave rollers 31.

[0141] exist Figure 10 The image shows a portion of the peripheral surface of the convex roller 31 (first roller).

[0142] The convex-concave roller 31 is a roller-shaped structure formed by combining multiple spur gears 31a, 31b, ... with a specified tooth width. The teeth of each gear form a convex portion 35 with a concave-convex shape in the peripheral surface of the convex-concave roller 31. The front end face 35c of the convex portion 35 forms a pressure surface between itself and the front end face of the ultrasonic welding head 42 of the ultrasonic welding machine 41 (described later), i.e., the vibration application surface 42t, to apply pressure to the first and second pieces 1, 2, which are the objects to be welded.

[0143] The tooth width (axial length of the gear) of each gear constituting the convex roller 31 determines the Q-direction dimension of the protrusion 5 of the front panel 10, and the tooth length (rotational length of the gear) of each gear determines the P-direction dimension of the protrusion 5 of the front panel 10.

[0144] Adjacent gears are combined with their teeth pitches staggered by half a pitch. As a result, the peripheral surface of the convex roller 31 becomes concave-convex.

[0145] In the illustrated configuration, the front end face 35c of each protrusion 35 is formed into a rectangular shape with the long side as the rotation direction of the convex roller 31 and the short side as the axial direction.

[0146] When the front end face 35c has a shape that is longer in the direction of rotation, the contact time between one of the protrusions 35 of the convex roller 31 and the vibration application surface 42t of the front end of the ultrasonic welding head 42 is longer, which makes it easier to raise the temperature, so it is preferred.

[0147] The recesses of each gear in the convex-concave roller 31 form the concave-convex recesses in the peripheral surface of the convex-concave roller 31.

[0148] A suction hole 34 is formed at the bottom of the teeth (the bottom of the recess). The suction hole 34 is controlled to draw air from the meshing part 33 of the convex roller 31 and the convex roller 32 to the confluence part of the first plate 1 and the second plate 2 through a suction source (not shown) such as a blower or a vacuum pump.

[0149] Thus, the first piece 1, which is deformed into a concave-convex shape by the meshing of the concave-convex rollers 31 and 32, is conveyed to the confluence of the first piece 1 and the second piece 2 and the ultrasonic vibration application part 36 of the ultrasonic welding machine 41 by the suction force of the suction hole 34, while maintaining the shape of the deformation along the circumference of the concave-convex rollers 31.

[0150] exist Figure 10 In the convex-concave roller 31 shown, a predetermined gap G is provided between adjacent gears, thereby suppressing the occurrence of unreasonable elongation force applied to the first piece 1 or the first piece 1 being cut off by the meshing part 33 of the two rollers 31, 32. Therefore, the first piece 1 is easily deformed into a concave-convex shape along the shape of the circumferential surface of the convex-concave roller 31.

[0151] The convex-concave roller 32 (the second roller) has a concave-convex shape on its circumferential surface that meshes with the concave-convex shape on the circumferential surface of the convex-concave roller 31. The convex-concave roller 32 has the same structure as the convex-concave roller 31, except that it does not have the suction hole 34.

[0152] Furthermore, assuming that the concave and convex portions of the two rollers 31 and 32 mesh with each other, the diameters of the concave and convex rollers 31 and 32 can be different. By rotating the two rollers 31 and 32 with meshing concave and convex portions while guiding the first piece 1 into the meshing portion 33 of the two rollers 31 and 32, the first piece 1 can be deformed into a concave and convex shape.

[0153] In the engagement portion 33, multiple portions of the first piece 1 are pressed into the recesses of the peripheral surface of the convex roller 31 by the protrusions of the convex roller 32, and the pressed portions become the protrusions 5 of the manufactured front piece 10.

[0154] Multiple protrusions are formed on the peripheral surface of the convex roller 32, which are inserted into the recesses of the convex roller 31. However, it is not necessary for the convex roller 32 to form protrusions that correspond to all the recesses of the convex roller 31.

[0155] also, Figure 9 As described above, the embossing portion 30 includes two embossed rollers with concave and convex surfaces on their peripheral surfaces. The two rollers 31 and 32 are rotated to form an engagement portion 33 where the concave and convex surfaces of the two rollers 31 and 32 interlock, guiding the first piece 1 into the engagement portion 33, thereby deforming the first piece 1 into an embossed shape. However, the embossed rollers in the embossing portion 30 may only be the embossed roller 31 capable of attracting the first piece 1 to its peripheral surface; that is, the embossed roller 32 may be absent. In this case, as long as the first piece 1 is guided to the peripheral surface of the embossed roller 31, the suction hole 34 (see reference) disposed on that peripheral surface can be used. Figure 10 The suction force generated by the roller 31 causes the first piece 1 to deform in a manner that follows the concave and convex shape of the peripheral surface. This following and deformation of the first piece 1 caused by the suction at the peripheral surface of the roller 31 can be achieved by appropriately adjusting the suction force and the configuration of the suction hole 34.

[0156] The ultrasonic processing unit 40 includes an ultrasonic welding machine 41 with an ultrasonic welding head 42. A second sheet 2 is overlapped onto a first sheet 1 deformed into a concave-convex shape. These two sheets 1 and 2 are sandwiched between the protrusion 35 of the concave-convex roller 31 and the vibration application surface 42t of the front end of the ultrasonic welding head 42, and ultrasonic vibration is applied, thereby forming a through hole 6 and fusing the first sheet 1 and the second sheet 2. Furthermore, a fiber orientation region 20 is formed in a portion of the opening end 6e of the through hole 6.

[0157] Ultrasonic welding machine 41 Figure 9 and Figure 11 As shown, it has an ultrasonic oscillator (not shown), a converter 43, an amplitude transformer 44, and an ultrasonic welding head 42.

[0158] An ultrasonic oscillator (not shown) is electrically connected to a converter 43, and a high-voltage electrical signal with a wavelength of 15 to 50 kHz generated by the ultrasonic oscillator is input to the converter 43.

[0159] An ultrasonic oscillator (not shown) is mounted on or outside the movable stage 45.

[0160] The converter 43 incorporates a piezoelectric element, such as a piezoelectric element, which converts the electrical signal input from the ultrasonic oscillator into mechanical vibration. The amplitude transformer 44 adjusts, preferably amplifies, the amplitude of the mechanical vibration generated from the converter 43 and transmits it to the ultrasonic welding head 42.

[0161] The ultrasonic welding head 42 is formed from a block of metal such as aluminum alloy or titanium alloy and is designed to resonate appropriately at the frequency in use.

[0162] The ultrasonic vibrations transmitted from the amplitude transformer 44 to the ultrasonic welding head 42 are amplified or attenuated inside the ultrasonic welding head 42 and applied to the first and second pieces 1 and 2, which are the objects to be welded. As this ultrasonic welding machine 41, commercially available ultrasonic welding heads, converters, amplitude transformers, and ultrasonic oscillators can be used in combination.

[0163] The ultrasonic welding machine 41 is fixed on the movable stage 45, and the position of the movable stage 45 moves forward and backward along the direction close to the circumferential surface of the convex and concave roller 31. This allows adjustment of the gap between the vibration application surface 42t, which is the front end face of the ultrasonic welding head 42, and the front end face 35c of the protrusion 35 of the first roller 31, as well as the pressure applied to the stacked first and second pieces 1 and 2.

[0164] The first and second pieces 1 and 2, which are to be welded, are sandwiched between the front end face 35c of the protrusion 35 of the convex roller 31 and the vibration application surface 42t of the front end of the ultrasonic welding head 42 of the ultrasonic welding machine 41, and pressure is applied. Ultrasonic vibration is applied to the two pieces 1 and 2, thereby heating the portion of the two pieces 1 and 2 located on the front end face 35c of the protrusion 35. The first piece 1 and / or the second piece 2 melt and then solidify again. Thus, a through hole 6 is formed through the two pieces 1 and 2, and a welded portion that joins the two pieces 1 and 2. The welded portion is formed along the opening end 6e of the through hole 6.

[0165] The vibration application surface 42t at the front end of the ultrasonic welding head 42 is made of a metal such as aluminum alloy or titanium alloy. The main body 420 of the ultrasonic welding head 42 (see reference) Figure 11 The front end of the ) is formed and welded to the object to be welded, more specifically to the second piece 2.

[0166] The manufacturing apparatus 100 has a preheating component 51 that preheats at least one of the first sheet 1 and the second sheet 2 before ultrasonic vibration is applied.

[0167] The preheating component 51 is disposed inside the convex roller 31 (first roller) and extends parallel to the rotation axis (CD) of the convex roller 31.

[0168] In addition, a plurality of preheating components 51 are arranged at intervals in the circumferential direction near the outer periphery around the rotating shaft of the convex roller 31.

[0169] As a preheating component 51, a mechanism that applies heat energy to the object to be heated (first piece 1, second piece 2) from the outside can be used for heating. For example, a cartridge heater with electric heating wire can be used, but it is not limited to this, and various known heating mechanisms can be used without particular limitation.

[0170] The preheating component 51 is part of the preheating mechanism 50.

[0171] In addition to the preheating component 51, the preheating mechanism 50 also includes a temperature measuring mechanism (not shown) capable of measuring the temperature of the object to be welded before ultrasonic vibration is applied, and a temperature control unit (not shown) that controls the temperature of the preheating component 51 based on the measurement value of the temperature measuring mechanism.

[0172] The heating temperature of the peripheral surface of the concave-convex roller 31 of the preheating component 51 is controlled by the aforementioned temperature control unit. The preheating mechanism 50 can maintain the temperature of the first piece 1, which is introduced into the ultrasonic vibration application unit 36 ​​during the operation of the manufacturing apparatus 100, within a specified range.

[0173] Manufacturing device 100 Figure 12 As shown, it has a welding head heating component 61, which heats the ultrasonic welding head 42, which includes a vibration application surface 42t.

[0174] The welding head heating element 61 is not disposed on the vibration application surface 42t, but is fixed near the vibration application surface 42t, specifically on the side of the front end of the ultrasonic welding head 42.

[0175] As the welding head heating component 61, various known heating mechanisms such as heaters can be used without particular restrictions.

[0176] The welding head heating component 61 is part of the welding head heating mechanism 60.

[0177] In addition to the welding head heating component 61, the welding head heating mechanism 60 also includes a temperature measuring mechanism (not shown) capable of measuring the temperature of the vibration application surface 42t, and a temperature control unit (not shown) that controls the temperature of the welding head heating component 61 based on the measured value of the temperature measuring mechanism.

[0178] The heating temperature of the vibration application surface 42t of the welding head heating component 61 is controlled by the aforementioned temperature control unit. The welding head heating mechanism 60 can maintain the temperature of the vibration application surface 42t within a specified range during the operation of the manufacturing apparatus 100.

[0179] Furthermore, the ultrasonic welding machine 41 is a device that applies ultrasonic vibrations to the object to be welded, thereby causing the object to heat up and melt, and is clearly distinguished from the preheating component 51 and the welding head heating component 61 mentioned above.

[0180] In the manufacturing apparatus 100, a groove-shaped recess 46 is formed on the vibration application surface 42t of the ultrasonic welding head 42. Figure 13 The diagram shows a schematic cross-sectional view along the MD of the front end of the ultrasonic welding head 42. Figure 14 The diagram shows a schematic plan view of the vibration application surface 42t of the ultrasonic welding head 42. Figure 13 yes Figure 12 The enlarged cross-sectional view of the front end of the ultrasonic welding head 42 is shown.

[0181] The grooved recess 46 extends along the rotation axis (CD) of the convex roller 31 (first roller). "Extends along the rotation axis (CD)" means that the angle between the grooved recess 46 and the rotation axis (CD) of the convex roller 31 is less than 45 degrees. Figure 14 The groove-shaped recess 46 shown extends parallel to the rotation axis (CD) and forms an angle of zero with the rotation axis (CD).

[0182] In the manufacturing apparatus 100, a groove-shaped recess 46 is formed on the vibration application surface 42t. This groove-shaped recess 46 is as follows: Figure 14 As shown, it is located at the center of the length along MD of the vibration application surface 42t, and extends along the entire length of CD.

[0183] The groove-shaped recess 46 is as follows Figure 13 The cross-sectional view shown is along a direction orthogonal to the rotation axis of the concave-convex roller 31 (i.e., MD), and is defined by a pair of concave side surfaces 46a, 46a and a concave bottom surface 46b.

[0184] A pair of concave side surfaces 46a, 46a intersect with the vibration application surface 42t, and more specifically, are connected to the vibration application surface 42t and extend in a direction away from the vibration application surface 42t.

[0185] The bottom surface 46b of the recess is connected to the longitudinal ends of the pair of recessed side surfaces 46a, 46a, and is opposite to the opening 46d of the groove-shaped recess 46.

[0186] exist Figure 12 ( Figure 13In the ultrasonic welding head 42 shown, the corner 46c where the concave side 46a intersects the vibration application surface 42t is sharp, and the bottom surface 46b of the concave portion forms an arc shape that is recessed in the direction away from the opening 46d in the cross-sectional view along MD.

[0187] exist Figure 12 ( Figure 13 In the configuration shown, the angle between the concave side 46a and the vibration application surface 42t is 90 degrees. That is, the angle formed by the corner 46c is 90 degrees.

[0188] The manufacturing method of the front sheet 10 using the manufacturing apparatus 100 configured as described above includes a shaping process in which a first sheet 1 is deformed into a concave-convex shape while rotating a concave-convex roller 31 (first roller) with concave-convex surfaces on the peripheral surface.

[0189] In addition, the manufacturing method of the front sheet 10 using the manufacturing apparatus 100 includes an overlapping process in which a first sheet 1, which is deformed into a concave-convex shape, is held on a concave-convex roller 31 and conveyed, and a second sheet 2 is overlapped on the conveyed first sheet 1.

[0190] In addition, the manufacturing method of the front sheet 10 of the manufacturing apparatus 100 includes an ultrasonic processing step in which two overlapping sheets 1 and 2 are sandwiched between the protrusion 35 of the convex roller 31 and the vibration application surface 42t of the front end of the ultrasonic welding head 42 of the ultrasonic welding machine 41 to apply ultrasonic vibration.

[0191] In the above shaping process, the first piece 1 is guided into the meshing part 33 of the two concave and convex rollers 31 and 32, so that the first piece 1 is deformed into a concave and convex shape.

[0192] From the viewpoint of facilitating the formation of fiber orientation region 20 and through hole 6, the angle θ35 of the corner of the front end of protrusion 35 in a cross-sectional view (along the MD) along a direction orthogonal to the rotation axis of the convex roller 31 (first roller) (refer to...) Figure 12 The temperature is preferably 90 degrees or higher, more preferably 105 degrees or higher, and even more preferably less than 135 degrees, and more preferably less than 120 degrees.

[0193] In the above-described ultrasonic processing step, an ultrasonic welding head is used as the specific ultrasonic welding head described above, namely, an ultrasonic welding head 42 with a groove-shaped recess 46 extending along the rotation axis (CD) of the convex roller 31 (first roller) formed on the vibration application surface 42t, and ultrasonic vibration is applied, thereby forming a through hole 6 in the stack of the overlapping first piece 1 and second piece 2 (the object to be welded), and forming a welded portion for welding the first piece 1 and the second piece 2, and forming a fiber orientation region 20 in a portion of the opening end 6e of the through hole 6.

[0194] In the above-mentioned ultrasonic treatment process, such as Figure 12 As shown, the objects to be welded (a stack of the first piece 1 and the second piece 2) are conveyed on the MD and ultrasonic vibration is applied between the front end face 35c of the protrusion 35 of the convex roller 31 and the vibration application surface 42t of the ultrasonic welding head 42, which has a grooved recess 46.

[0195] Here, on the vibration application surface 42t that presses the object to be welded toward the protrusion 35, such as... Figure 13 As shown, there is a pair of corner portions 46c, 46c at the front and rear of the MD, with the opening 46d sandwiching the groove-shaped recess 46. Therefore, the stress generated when pressing the object to be welded is concentrated at the corner 46c. The shear force applied to the object to be welded through the corner 46c is higher than when the corner 46c (groove-shaped recess 46) is not formed. Therefore, in the above-mentioned ultrasonic treatment process, for the object to be welded, not only is the heat generated by the ultrasonic vibration of the object to be welded applied, but also the strong shear force caused by the groove-shaped recess 46 is applied. As a result, in the part of the object to be welded that is sandwiched between the front end face 35c of the protrusion 35 and the vibration application surface 42t of the ultrasonic welding head 42, a welded portion, a through hole 6 and a fiber orientation region 20 can be formed simultaneously.

[0196] Based on the above ultrasonic processing procedure, even if the resin used to form the first sheet 1 and / or the second sheet 2 is a high melting point resin (e.g., PET) with a melting point exceeding 200°C, the welded portion, the through hole 6, and the fiber orientation region 20 can be formed simultaneously.

[0197] In the aforementioned ultrasonic processing step, it is believed that an ultrasonic welding head (referring to [reference]) with a groove-shaped recess extending along the rotation axis of the convex and concave rollers formed on the vibration application surface is used. Figures 12-14This facilitates the formation of a fiber-oriented region 20 in a portion of the opening end 6e of the through hole 6. The method for forming this fiber-oriented region 20 will be described below. In the aforementioned ultrasonic processing step, the objects to be welded (a stack of the first sheet 1 and the second sheet 2) are conveyed on the MD, and ultrasonic vibration is applied between the front end face 35c of the protrusion 35 of the convex roller 31 and the vibration application surface 42t of the ultrasonic welding head 42, which has a grooved recess 46. This forms a molten portion where the first sheet 1 and the second sheet 2 are fused. On the other hand, the stress generated when pressing the objects to be welded is concentrated at a pair of corners 46c located before and after the opening 46d of the grooved recess 46 on the MD, specifically the corner 46c located on the front (downstream) side of the MD. Therefore, a shear force is applied along the MD via this corner 46c to the objects to be welded, particularly around the periphery where the through hole 6 is formed. Through this shear force, the contact portions of the front and rear sides of the MD in the welded object with the corners 46c, 46c break, forming a through hole 6. Since the side portion of the through hole 6 is stretched along the MD, the fibers located on this side portion are oriented along the MD, forming a fiber orientation region 20. Furthermore, when the welded object breaks due to the aforementioned shear force, in the thickness direction of the welded object, since it is stretched in a direction away from the first piece 1, the fibers 21 in this thickness direction are oriented in a direction away from the first piece 1. In this way, using the shear force along the MD, a fiber orientation region 20 is formed on the side portion of the through hole 6 along its long side.

[0198] From the viewpoint that it is easier to form the fiber orientation region 20, in the above-mentioned ultrasonic processing step, the pressure applied to the first and second pieces 1 and 2 between the front end face 35c of the protrusion 35 of the convex roller 31 (first roller) and the vibration application surface 42t of the ultrasonic welding head 42 is preferably 20 N / mm or more, and more preferably 30 N / mm or more.

[0199] Furthermore, the applied pressure is preferably 80 N / mm or less, and more preferably 70 N / mm or less.

[0200] The “pressure” referred to here is the so-called line pressure, which is represented by the value (pressure per unit length) obtained by dividing the pressure (N) of the ultrasonic welding head 42 by the total length of the tooth width (the length of the protrusion 35 along CD) of the protrusion 35 in contact with the ultrasonic welding head 42 (excluding the concave part of the convex roller 31).

[0201] From the same point of view as above, the frequency of the applied ultrasonic vibration is preferably 15 kHz or higher, and more preferably 20 kHz or higher.

[0202] Furthermore, the aforementioned frequency is preferably 50 kHz or less, and more preferably 40 kHz or less.

[0203] Furthermore, from the same point of view, the amplitude of the applied ultrasonic vibration is preferably 20 μm or more, and more preferably 25 μm or more.

[0204] In addition, the amplitude is preferably 50 μm or less, and more preferably 40 μm or less.

[0205] When measuring the frequency and amplitude of ultrasonic vibration, a laser displacement meter or similar device is used to measure the displacement of the front end of the ultrasonic welding head. The frequency and amplitude are measured at a sampling rate of 200kHz or higher and an accuracy of 1μm or higher.

[0206] From the same perspective as above, the conveying speed of the object to be welded (the stack of the first piece 1 and the second piece 2) in the above-mentioned ultrasonic processing step is preferably 200 m / min or more, more preferably 250 m / min or more, and even more preferably 400 m / min or less, more preferably 350 m / min or less.

[0207] Based on the same viewpoint described above, in the ultrasonic processing step, the tension applied to the object to be welded (the laminate of the first sheet 1 and the second sheet 2) during transport is preferably 20 N / m or more, more preferably 30 N / m or more, and even more preferably 90 N / m or less, more preferably 60 N / m or less. In this embodiment, the tension can be adjusted by changing the transport speed of the object to be welded prior to the ultrasonic processing step.

[0208] According to this embodiment, the ultrasonic welding head 42, such as Figure 13 As shown, since the corner 46c of the opening 46d that defines the groove 46 is sharp, compared with the case where the corner 46c is not sharp and has an arc, the shear force applied to the welding object (the laminate of the first piece 1 and the second piece 2) in the above-mentioned ultrasonic processing process is higher, so the welding part, the through hole 6 and the fiber orientation region 20 can be formed more reliably at the same time.

[0209] From the viewpoint of making the effect produced by the corner 46c more reliable, the angle between the concave side 46a in the corner 46c and the vibration application surface 42t is preferably 45 degrees or more, and more preferably 60 degrees or more.

[0210] Furthermore, the aforementioned angle is preferably 135 degrees or less, and more preferably 120 degrees or less.

[0211] On the other hand, if a groove-shaped recess 46 is formed on the vibration application surface 42t of the ultrasonic welding head 42, the durability of the ultrasonic welding head 42 (especially the main body 420) will be reduced, and there is concern that cracks (fissures) may originate from the groove-shaped recess 46 and enter the main body 420 during ultrasonic vibration. To address this, in the ultrasonic welding head 42, by defining the bottom surface 46b of the recess 46, the groove-shaped recess 46 is... Figure 13 In the cross-sectional view along MD shown, the ultrasonic welding head 42 is formed into an arc shape that is concave in the direction away from the opening 46d, which can eliminate such concerns.

[0212] From the viewpoint of making the effect produced by such a concave bottom surface 46b more reliably exerted, the curvature of the concave bottom surface 46b is preferably 1 or more, and more preferably 2 or more.

[0213] Furthermore, the curvature of the concave bottom surface 46b is preferably 10 or less, and more preferably 5 or less.

[0214] From the viewpoint of making the effect produced by the groove-shaped recess 46 more reliably exerted, it is preferable that the size of the groove-shaped recess 46 be set in the following manner.

[0215] The width W of the groove-shaped recess 46 (refer to) Figure 13 and Figure 14 The thickness is preferably 0.2 mm or more, and more preferably 0.5 mm or more.

[0216] In addition, the width W is preferably 2 mm or less, and more preferably 1 mm or less.

[0217] The width W0 of the vibration application surface 42t (refer to) Figure 14 Preferably, the diameter is 5mm or more, and more preferably 10mm or more.

[0218] In addition, the width W0 is preferably 20 mm or less, and more preferably 15 mm or less.

[0219] The length of the groove-shaped recess 46 along CD is the length L along the rotation axis of the concave-convex roller 31 (first roller) (refer to...). Figure 14 ), and the length L0 along this direction of the vibration application surface 42t (refer to Figure 14 When the ratio of length L to length L0 is expressed as length L, it is preferably 0.2 or more, and more preferably 0.3 or more.

[0220] Furthermore, the aforementioned ratio (length L / length L0) is preferably 1 or less.

[0221] exist Figure 14 In the manner shown, the groove-shaped recess 46 extends along the entire length of CD of the vibration application surface 42t, with the length L being the same as the length L0, and the ratio mentioned above being 1.

[0222] The length L0 of the vibration application surface 42t along CD is preferably 30 mm or more, and more preferably 50 mm or more.

[0223] In addition, the length L0 is preferably 200 mm or less, and more preferably 150 mm or less.

[0224] Depth D of groove-shaped recessed portion 46 (refer to Figure 13 The length of the portion of the recess from the vibration application surface 42t to the part furthest from the vibration application surface 42t in the bottom surface 46b of the recess, preferably 0.3 mm or more, more preferably 0.5 mm or more.

[0225] In addition, the depth D is preferably 5 mm or less, and more preferably 2 mm or less.

[0226] The groove-shaped recess 46 is preferably formed in the central part of the MD of the vibration application surface 42t, and more preferably in the area within 5 mm, more preferably within 3 mm, on the upstream side of the MD from the center of the MD of the vibration application surface 42t.

[0227] exist Figure 14 In the manner shown, the groove-shaped recess 46 is formed in the center of the MD of the vibration application surface 42t.

[0228] As described above, the manufacturing apparatus 100 has a preheating component 51 (preheating mechanism 50). In the manufacturing method of the front sheet 10 using the manufacturing apparatus 100, since at least one of the first sheet 1 and the second sheet 2 supplied to the ultrasonic treatment process is preheated by the preheating component 51, the welding portion, the through hole 6 and the fiber orientation region 20 can be formed more reliably in conjunction with the effect of the groove recess 46.

[0229] The preheating conditions for the objects to be welded by the preheating component 51 are not particularly limited, and can be adjusted appropriately according to the type of objects to be welded. However, it is preferable to heat at least one of the first piece 1 and the second piece 2 to a temperature lower than the melting point of that piece and at least 50°C below that melting point. That is, before applying ultrasonic vibration, it is preferable to perform either or both of the following (1) and (2): (1) Preheat the first piece 1 to a temperature lower than the melting point of that piece and at least 50°C below that melting point. (2) Preheat the second piece 2 to a temperature lower than the melting point of that piece and at least 50°C below that melting point.

[0230] Preferably, the first piece 1 is preheated to a temperature at least 50°C lower than the melting point of the first piece, and the second piece 2 is preheated to a temperature at least 50°C lower than the melting point of the second piece.

[0231] As described in (1) above, the method of heating the first piece 1 to a temperature that is lower than the melting point of the first piece 1 and 50°C or higher, for example, measuring the temperature of the first piece 1 on the convex roller 31 (first roller) between the meshing part 33 of the convex rollers 31 and 32 and the ultrasonic vibration application part 36 of the ultrasonic welding machine 41, and controlling the temperature of the preheating member 51 so that the measured value is within the specific range described above.

[0232] As a method for preheating the first piece 1 to a specific temperature range, various methods can be used instead of using a heater disposed in the convex roller 31 to control the temperature of the peripheral surface of the convex roller 31 to make the first piece 1 reach a specific temperature range.

[0233] For example, a heater, a hot air outlet, and a far-infrared irradiation device can be provided near the periphery of the convex roller 31, and the temperature of the periphery of the convex roller 31 before or after it is bonded to the first piece 1 can be controlled by using these. Alternatively, the temperature of the first piece 1 can be controlled by heating the convex roller 32 (second roller) that contacts the first piece 1 at the meshing part 33.

[0234] Alternatively, for example, the first piece 1 that is attached to the front of the convex roller 31 can be brought into contact with the heated roller, or it can be passed through a space that is maintained at a high temperature, or hot air can be blown on it.

[0235] As for the method described in (2) above, namely, heating the second piece 2 to a temperature that is lower than the melting point of the second piece 2 and 50°C or higher than the melting point, it is preferable to use a temperature measuring mechanism disposed in the transport path of the second piece 2 to measure the temperature of the second piece 2 before it merges with the first piece 1, and control the temperature of the heating mechanism (not shown) disposed in the transport path of the second piece 2 so that the measured value is within the specific range described above.

[0236] The heating mechanism of the second piece 2 can be a contact method that brings the heated roller or the like into contact with it, or it can be a non-contact method that brings it through a space maintained at a high temperature, or blows or circulates hot air, or irradiates it with infrared rays.

[0237] The melting points of the first piece 1 and the second piece 2 can be measured, for example, using a differential scanning calorimeter (DSC) PYRIS Diamond DSC manufactured by Perkin-Elmer. In this measurement method, the melting points of the measured objects (first piece 1 and second piece 2) are calculated based on the peak values ​​of the measurement data.

[0238] If the first sheet 1 or the second sheet 2 is a non-woven fabric or other fiber sheet, and its constituent fibers are composite fibers composed of multiple components such as core-sheath type or parallel type, the melting point of the sheet is taken as the lowest temperature melting point among multiple melting points measured by DSC.

[0239] Furthermore, as described above, the manufacturing apparatus 100 has a welding head heating component 61 (welding head heating mechanism 60). In the ultrasonic treatment process described above, since the vibration application surface 42t heated by the welding head heating component 61 comes into contact with the object to be welded (a stack of the first piece 1 and the second piece 2), the welding portion, through hole 6 and fiber orientation region 20 can be formed simultaneously in a more reliable manner, complementing the effect of the groove recess 46.

[0240] There are no particular restrictions on the heating conditions of the welding head heating element 61; they can be adjusted appropriately according to the type of object to be welded.

[0241] For example, the method described above (2) can be implemented by using a welding head heating component 61 instead of a preheating component 51. That is, by controlling the temperature of the ultrasonic welding head 42 (vibration application surface 42t) heated by the welding head heating component 61, the temperature of the second piece 2 to which ultrasonic vibration is to be applied can be preheated to a temperature that is lower than the melting point of the second piece 2 and 50°C or lower than the melting point. In this state, ultrasonic vibration is applied to the first and second pieces 1 and 2 sandwiched between the protrusion 35 of the convex roller 31 and the vibration application surface 42t.

[0242] In addition, either the preheating component 51 or the welding head heating component 61 can be used alone or both can be used together.

[0243] From the viewpoint that it is easier to form the through holes 6 and the fiber orientation region 20, in the manufacturing method of the front sheet 10, the first sheet 1 and the second sheet 2 are preferably spunbond nonwoven fabrics containing core-sheath type composite fibers as constituent fibers. As the aforementioned core-sheath type composite fiber, it is preferable to use a core-sheath type composite fiber with polyethylene terephthalate (PET) as the core and polyethylene (PE) as the sheath.

[0244] Figures 15-18 The image shows the main part (front end) of another embodiment of the ultrasonic welding head.

[0245] Regarding the embodiments described below, the description will focus on the components that differ from the ultrasonic welding head 42 described above; identical components will be labeled with the same reference numerals and will be omitted from the description. For components not specifically described, the description of the ultrasonic welding head 42 will be applied as appropriate.

[0246] exist Figure 15 In the ultrasonic welding head 42A shown, in the cross-sectional view along MD of the ultrasonic welding head 42 as shown in the figure, the bottom surface 46b of the groove-shaped recess 46 is a straight line, and the groove-shaped recess 46 is formed into a rectangular shape in this cross-sectional view. That is, the bottom surface 46b of the recess in the ultrasonic welding head 42A is flat.

[0247] When using ultrasonic welding head 42A, it achieves essentially the same effect as when using ultrasonic welding head 42. However, from the viewpoint of further reliably suppressing the reduction in durability of the ultrasonic welding head 42 due to the formation of the groove-shaped recess 46, and the resulting cracks and other adverse conditions, the shape of the bottom surface 46b of the recess in the cross-sectional view is as follows: Figure 13 The shape shown is preferably an arc that is recessed in the direction away from the opening 46d.

[0248] exist Figure 16 In the ultrasonic welding head 42B shown, the vibration application surface 42t, when viewed along a cross section orthogonal to the rotation axis of the convex roller 31 (first roller), forms an arc shape that is concave in the direction away from the rotation axis.

[0249] Furthermore, the vibration application surface 42t mentioned here assumes the absence of the groove-shaped recess 46. More specifically, in cases such as Figure 16 The cross-sectional view along MD shown is a surface that imaginarily extends the vibration application surface 42t from one corner 46c of MD to the other corner 46c, with the opening 46d of the groove 46 sandwiched between it.

[0250] The cross-sectional shape of the vibration application surface 42t along the MD is arc-shaped, thereby increasing the shear force applied to the welding object (the laminate of the first piece 1 and the second piece 2) in the above-mentioned ultrasonic processing step. Therefore, in conjunction with the effect produced by the groove 46, the welding part, the through hole 6 and the fiber orientation region 20 can be formed more reliably at the same time.

[0251] In such Figure 16 In the cross-sectional view along MD shown, the arc-shaped vibration application surface 42t is formed, preferably curved along a circular track (not shown) through which the front end of the protrusion 35 of the convex roller 31 (first roller) passes. This increases the time the object to be welded (the laminate of the first sheet 1 and the second sheet 2) is sandwiched between the front end surface 35c of the protrusion 35 and the vibration application surface 42t, enabling more reliable simultaneous formation of the welded portion, the through hole 6, and the fiber orientation region 20.

[0252] In addition, when the vibration application surface 42t of the ultrasonic welding head 42 is formed in an arc shape in the cross-sectional view along MD, it is preferable that the front end face 35c of each of the plurality of protrusions 35 of the corresponding convex roller 31 is formed in a convex shape in the cross-sectional view in a direction away from the rotation axis of the convex roller 31, and the bending direction is consistent with the vibration application surface 42t.

[0253] The radius of curvature of the vibration application surface 42t of the ultrasonic welding head 42B is preferably 100% or more relative to the radius of curvature of the front end surface 35c of the protrusion 35 of the convex roller 31.

[0254] In addition, the radius of curvature of the vibration application surface 42t is preferably 500% or less, more preferably 200% or less.

[0255] In addition, Figure 16 In the ultrasonic welding head 42B shown, the vibration application surface 42t is formed in an arc shape along the cross-sectional shape of MD in the entire region in the direction parallel to the rotation axis of the convex roller 31. However, different cross-sectional shapes may be provided in parts such as those in the direction parallel to the rotation axis that do not have a protrusion 35.

[0256] For example, Figure 10 As shown, when a gap G is provided between adjacent gears constituting the convex and concave rollers 31, a flat portion that does not protrude from the arc-shaped vibration application surface 42t may also be provided at the part opposite to the gap G in the vibration application surface 42t.

[0257] Figure 17 In the ultrasonic welding head 42C shown, the front end of the ultrasonic welding head 42 includes a heat storage part 421 of a metal main body 420 fixed to the ultrasonic welding head 42C, and the vibration application surface 42t is formed by the heat storage part 421.

[0258] The groove-shaped recess 46 is formed at least in the heat storage section 421.

[0259] exist Figure 17 In the middle, the groove-shaped recess 46 is only formed in the heat storage part 421, but it can also extend through the heat storage part 421 in the thickness direction and extend to the main body part 420.

[0260] in addition, Figure 17 The vibration application surface 42t, which is composed of the heat storage part 421, is formed in an arc shape in the cross-sectional view along MD, similar to the vibration application surface 42t of the ultrasonic welding head 42B described above. However, it may not be formed in an arc shape but rather flat.

[0261] The heat storage section 421 is formed of a heat storage material that has a lower thermal conductivity than the metal constituting the main body section 420.

[0262] The thermal conductivity of the heat storage material constituting the heat storage section 421 is preferably 2.0 W / mK or less, and more preferably 1.0 W / mK or less, from the viewpoint that it is difficult to dissipate heat to the ultrasonic welding head and the atmosphere.

[0263] Furthermore, from the viewpoint of an effective heating element, the thermal conductivity of the aforementioned heat storage material is preferably 0.1 W / mK or higher, and more preferably 0.5 W / mK or higher.

[0264] The thermal conductivity of heat storage materials can be measured using a thermal conductivity measuring device according to conventional methods.

[0265] When the vibration application surface 42t is formed by the heat storage section 421, the heat generated by the ultrasonic vibration of the first and second pieces 1 and 2 is stored in the heat storage section 421. As a result, the temperature of the heat storage section 421 rises, which can heat the first piece 1 and the second piece 2. Therefore, in conjunction with the effect of the groove-shaped recess 46 formed on the vibration application surface 42t, the simultaneous formation of the weld section, the through hole 6, and the fiber orientation region 20 can be further made more reliable.

[0266] In addition, when the vibration application surface 42t is formed by the heat storage part 421, it has the advantage of suppressing the occurrence of adverse conditions such as the adhesion of molten resin to the conveying mechanism and the wrapping of the sheet to the conveying roller caused by the melting of the first and second sheets 1 and 2, and reducing the maintenance burden of the manufacturing equipment.

[0267] The thickness Th of the heat storage section 421 (refer to) Figure 17 There are no particular limitations, but from the viewpoint of more reliably maximizing the effect of the heat storage section 421, it is preferable to have a thickness of 5 μm or more, and more preferably 10 μm or more.

[0268] In addition, the thickness Th is preferably 100 μm or less, and more preferably 50 μm or less.

[0269] As the heat storage material constituting the heat storage section 421, a synthetic resin with excellent wear resistance and heat resistance is preferably used, provided that its thermal conductivity is lower than that of the metal constituting the main body section 420. Examples of such synthetic resins include polyimide, polybenzimidazole, polyether ethyl ketone, polyphenylene sulfide, polyetherimide, polyamide imide, etc., which have a Rockwell hardness of R120 or higher and R140 or lower, and a heat resistance temperature of 150°C or higher and 500°C or lower.

[0270] As the aforementioned heat storage material, synthetic resins such as polyimide and polybenzimidazole, having a Rockwell hardness of R125 or higher and R140 or lower, and a heat resistance temperature of 280°C or higher and 400°C or lower are particularly preferred.

[0271] Here, the Rockwell hardness is the value measured according to ASTM D-785, and the heat resistance temperature is the value measured according to ASTM D-648.

[0272] There are no particular restrictions on the means of fixing the heat storage part 421 made of synthetic resin to the main body part 420 made of metal, and known fixing mechanisms can be used.

[0273] The heat storage part 421 made of synthetic resin is formed, for example, by thermal spraying of a metal main body part 420, and can be fixed to the main body part 420.

[0274] The term "thermal spraying" as used herein refers to a known surface treatment method in which particles of thermal spraying materials such as metals or ceramics, which are molten or nearly molten by heating, collide at high speed with a substrate surface to form a coating.

[0275] As a thermal spraying material, any material that can be thermally sprayed and contributes to improving the fixing strength of the heat storage part 421 made of synthetic resin can be used without particular restrictions. From the viewpoint that the main body 420 made of metal such as titanium alloy has excellent bonding strength, wear resistance and heat resistance, ceramics such as tungsten carbide, zirconium oxide, and chromium carbide, alloys such as aluminum-magnesium alloy and zinc-aluminum alloy, metals such as aluminum, stainless steel, titanium, and molybdenum, and metal-ceramic composites such as cermet are preferred.

[0276] Figure 18 In the ultrasonic welding head 42D shown, a groove-shaped recess 47 in the vibration application surface 42t has a concave-convex portion 48 formed therein.

[0277] More specifically, such as Figure 18 As shown in (a), a portion of the non-formed groove recess 47 is a raised portion 48, and the remaining portion of the non-formed groove recess 47 is a smooth portion 49 without raised or recessed areas. The raised portion 48 has a larger surface roughness than the smooth portion 49, and therefore has a stronger frictional force.

[0278] In the above-mentioned ultrasonic processing step, shear force is applied to the portion of the object to be welded (the laminate of the first piece 1 and the second piece 2) pressed by the concave and convex portions 48. Therefore, in conjunction with the effect produced by the groove-shaped recess 46, the welded portion, the through hole 6 and the fiber orientation region 20 can be formed more reliably at the same time.

[0279] 48 concave and convex parts Figure 18 As shown in (b), it has multiple protrusions 481 and multiple recesses 482. The protrusions 481 are formed as triangles in the cross-sectional view along MD as shown in the figure, but the shape of the protrusions 481 in the cross-sectional view is not particularly limited, for example, it can also be quadrilateral, trapezoid, etc.

[0280] In addition, as an example of the arrangement pattern of the plurality of protrusions 481 in the concave and convex portions 48, an example can be given of an arrangement pattern in which the protrusions 481 are arranged at equal intervals on the CD (along the direction of rotation axis of the concave and convex roller 31) and the protrusions are arranged at equal intervals on the MD.

[0281] As another example of the above arrangement pattern, an example can be given of a pattern in which the protrusions 481 are arranged at equal intervals on the CD, the protrusions are arranged at equal intervals on the MD, and the adjacent protrusions on the MD are staggered by half a pitch.

[0282] The uneven portion 48 can be formed by knurling or thermal spraying the groove-shaped recessed non-forming portion 47 in the vibration application surface 42t.

[0283] exist Figure 18 In the manner shown, a smooth portion 49 exists between the grooved recess 46 and the convex portion 48, but it is also possible that the smooth portion 49 does not exist between the grooved recess 46 and the convex portion 48, and the grooved recess 46 and the convex portion 48 are adjacent on the MD.

[0284] Alternatively, the smooth portion 49 may not exist on the vibration application surface 42t, and the entire groove-shaped recessed portion 47 may be an uneven portion 48.

[0285] From the viewpoint of further reliably exerting the effect of the uneven portion 48, the surface roughness of the uneven portion 48 is preferably an arithmetic mean roughness Ra of 3.2 μm or more, and more preferably 6.3 μm or more.

[0286] Furthermore, regarding the surface roughness of such uneven portion 48, it is preferable that its arithmetic mean roughness Ra is 12.5 μm or less, more preferably 25 μm or less.

[0287] Arithmetic mean roughness Ra can be measured using various surface roughness measuring instruments, such as those manufactured by Mitutoyo Corporation.

[0288] From the same point of view, the dimensions of the protrusions and recesses 48 are preferably set in the following manner.

[0289] The ratio of the area (48S) of the concave-convex portion 48 to the area (47S) of the groove-shaped recess non-forming portion 47 of the vibration application surface 42t, i.e. the ratio calculated according to (48S / 47S)×100, is preferably 15% or more, more preferably 30% or more.

[0290] Furthermore, the above ratio is preferably 100% or less, and more preferably 80% or less.

[0291] The unit area (1 cm²) of the protrusion 481 constituting the concave-convex portion 48 2 The quantity is preferably one or more, more preferably one hundred or more.

[0292] In addition, the area per unit area (1cm²) of the protrusion 481 2 The quantity is preferably 1,000,000 or less, more preferably 10,000 or less.

[0293] When viewed from above, the area of ​​one protrusion 481 is preferably 0.0001 mm. 2 The above, more preferably 0.01mm 2 above.

[0294] Furthermore, the area of ​​one protrusion 481 is preferably 100 mm². 2 The following is more preferably 1mm 2 the following.

[0295] The present invention has been described above based on its preferred embodiments. The present invention is not limited to any of the above embodiments, and appropriate changes can be made without departing from the spirit of the present invention.

[0296] For example, the front sheet 10 of the above embodiment has a plurality of protrusions 5 and recesses 3, but it may also be a flat sheet without protrusions 5 and recesses 3.

[0297] Furthermore, the aforementioned front panel 10 has a laminated structure formed by stacking a first panel 1 and a second panel 2, but the front panel 10 can also be a single-layer structure. When the front panel 10 has a protrusion 5, from the viewpoint of further improving the strength of the protrusion 5 and further improving the resistance to body pressure of the wearer, the front panel 10 preferably has the aforementioned laminated structure.

[0298] Additionally, a single groove-shaped recess 46 may be formed on the vibration application surface 42t, but multiple recesses may also be formed. In this case, for example, multiple groove-shaped recesses 46 extending on the CD may be spaced apart on the MD, or multiple groove-shaped recesses 46 extending on the CD may be spaced apart on the CD.

[0299] Furthermore, the structure described in one of the above embodiments can also be applied to other embodiments.

[0300] For example, the vibration application surface 42t of the ultrasonic welding head 42D with the irregularities 48 (see reference). Figure 18 ),like Figure 16 As shown, it can also be formed as an arc shape that is recessed in the direction away from the rotation axis in a cross-sectional view along the direction orthogonal to the rotation axis of the convex roller 31 (a cross-sectional view along MD).

[0301] In addition, such as Figure 17 As shown, when the vibration application surface 42t is formed by the heat storage part 421, the vibration application surface 42t formed by the heat storage part 421 may also have a concave-convex part 48.

[0302] Regarding the embodiments of the present invention described above, the following absorbent articles are further disclosed.

[0303] <1>

[0304] An absorbent article having:

[0305] The front sheet, formed of fibrous material, has multiple through holes, and a portion of the open end of each through hole has a fiber orientation region in which the fibers are oriented in one direction; and

[0306] A fiber sheet is disposed adjacent to the non-skin-facing side of the front sheet.

[0307] The fibers in the fiber orientation region of the front sheet are engaged with the constituent fibers of the fiber sheet.

[0308] <2>

[0309] The above <1> The absorbent materials recorded in the text, among which,

[0310] The number of fibers located in the fiber orientation region in one of the through holes is 1 or more and 100 or less, preferably 5 or more and 100 or less, and more preferably 20 or more and 50 or less.

[0311] <3>

[0312] The above <1> or <2> The absorbent materials recorded in the text, among which,

[0313] In one of the through holes, the number of fibers located in the fiber orientation region and with their front ends facing the non-skin-opposite side in the thickness direction of the front sheet is 1 or more and 100 or less, preferably 20 or more and 100 or less.

[0314] <4>

[0315] The above <1> ~ <3> Any of the absorbent articles recorded in the text, among which,

[0316] The area ratio of the through hole in the front panel is 4% or more and 30% or less, preferably 8% or more and 20% or less.

[0317] <5>

[0318] The above <1> ~ <4> Any of the absorbent articles recorded in the text, among which,

[0319] The area of ​​one of the through holes is 1 mm. 2 Above and 30mm 2 The following is more preferably 3mm 2 Above and 20mm 2 the following.

[0320] <6>

[0321] The above <1> ~ <5> Any of the absorbent articles recorded in the text, among which,

[0322] The number of through holes forming the fiber orientation region in the front sheet is 2 or more and 20 or less per unit area (the area of ​​a 10mm square region when viewed from above), preferably 4 or more and 15 or less.

[0323] <7>

[0324] The above <1> ~ <6> Any of the absorbent articles recorded in the text, among which,

[0325] An absorber with liquid retention properties

[0326] The fiber sheet is a sublayer disposed between the front sheet and the absorber, or a packaged chip forming the surface of the absorber.

[0327] <8>

[0328] The above <1> ~ <7> Any of the absorbent articles recorded in the text, among which,

[0329] The fiber sheet has multiple recesses and protrusions.

[0330] <9>

[0331] The above <8> The absorbent materials recorded in the text, among which,

[0332] It has a longitudinal direction corresponding to the wearer's front-back direction and a transverse direction orthogonal to it.

[0333] The fibers located on the protrusion are oriented in the longitudinal direction.

[0334] <10>

[0335] The above <8> or <9> The absorbent materials recorded in the text, among which,

[0336] One or more of the protrusions in the fiber sheet overlap with the through hole.

[0337] <11>

[0338] The above <1> ~ <10> Any of the absorbent articles recorded in the text, among which,

[0339] The fiber sheet comprises hot-air nonwoven fabric.

[0340] <12>

[0341] The above <1> ~ <11> Any of the absorbent articles recorded in the text, among which,

[0342] It has a longitudinal direction corresponding to the wearer's front-back direction and a transverse direction orthogonal to it.

[0343] The fibers located in the fiber orientation region are oriented in a manner along the longitudinal direction.

[0344] <13>

[0345] The above <12> The absorbent materials recorded in the text, among which,

[0346] The through hole has a shape that is longer in the longitudinal direction.

[0347] The front sheet has fiber-oriented regions on both sides along the long side of the through hole.

[0348] The angle between the fiber located in the fiber orientation region and the reference line along the short side direction of the through hole is greater than 0 degrees and less than 90 degrees.

[0349] <14>

[0350] The above <13> The absorbent materials recorded in the text, among which,

[0351] The leading edge of the fiber located in the fiber orientation region faces the inside of the through hole.

[0352] <15>

[0353] The above <1> ~ <14> Any of the absorbent articles recorded in the text, among which,

[0354] In the front sheet, the fibers located in the fiber orientation region have fibers with a smaller fiber diameter compared to other fibers due to partial melting on the outer side.

[0355] <16>

[0356] The above <15> The absorbent materials recorded in the text, among which,

[0357] The fiber diameter of the fiber located in the fiber orientation region of the front sheet is 40% or more and 80% or less, preferably 50% or more and 70% or less, relative to the fiber diameter of the fiber located outside the fiber orientation region of the front sheet.

[0358] Industrial availability

[0359] The absorbent article according to the present invention can maintain the permeability of excrement and suppress the positional shift of the front sheet.

Claims

1. An absorbent article, characterized in that, have: The front sheet is formed of fibrous material and has multiple through holes, and a portion of the open end of the through hole has a fiber orientation region in which the fibers are oriented in one direction. and A fiber sheet is disposed adjacent to the non-skin-facing side of the front sheet. Multiple fibers in the front sheet located in the fiber orientation region intertwine with or become entangled with the constituent fibers of the fiber sheet, thereby engaging the multiple fibers in the fiber orientation region with the constituent fibers of the fiber sheet, thus joining the front sheet and the fiber sheet. As a fiber located in the fiber orientation region, the front sheet comprises a core-sheath type composite fiber with a fused sheath component and an exposed core component, exhibiting a smaller fiber diameter compared to other fibers. The multiple fibers located in the fiber orientation region extend in the same direction, and their front ends face the inside of the through hole.

2. The absorbent article as claimed in claim 1, characterized in that: The number of fibers located in the fiber orientation region in one of the through holes is more than one and less than 100.

3. The absorbent article as described in claim 1 or 2, characterized in that: In one of the through holes, the number of fibers located in the fiber orientation region and with their front ends facing the non-skin-opposite side in the thickness direction of the front sheet is more than 1 and less than 100.

4. The absorbent article as described in claim 1 or 2, characterized in that: The area ratio of the through hole in the front panel is more than 4% and less than 30%.

5. The absorbent article as described in claim 1 or 2, characterized in that: The area of ​​one of the through holes is 1 mm. 2 Above and 30mm 2 the following.

6. The absorbent article as claimed in claim 1 or 2, characterized in that: The number of through holes forming the fiber orientation region in the front sheet is more than 2 and less than 20 per unit area, that is, the area of ​​a 10mm square region when viewed from above.

7. The absorbent article as claimed in claim 1 or 2, characterized in that: An absorber with liquid retention properties The fiber sheet is a sublayer disposed between the front sheet and the absorber, or a packaged chip forming the surface of the absorber.

8. The absorbent article as claimed in claim 1 or 2, characterized in that: The fiber sheet has multiple recesses and protrusions.

9. The absorbent article as claimed in claim 8, characterized in that: It has a longitudinal direction corresponding to the wearer's front-back direction and a transverse direction orthogonal to it. The fibers located on the protrusion are oriented in the longitudinal direction.

10. The absorbent article as claimed in claim 8, characterized in that: One or more of the protrusions in the fiber sheet overlap with the through hole.

11. The absorbent article as claimed in claim 1 or 2, characterized in that: The fiber sheet comprises hot-air nonwoven fabric.

12. The absorbent article as claimed in claim 1 or 2, characterized in that: It has a longitudinal direction corresponding to the wearer's front-back direction and a transverse direction orthogonal to it. The fibers located in the fiber orientation region are oriented in a manner along the longitudinal direction.

13. The absorbent article as claimed in claim 12, characterized in that: The through hole has a shape that is longer in the longitudinal direction. The front sheet has fiber-oriented regions on both sides along the long side of the through hole. The angle between the fiber located in the fiber orientation region and the reference line along the short side direction of the through hole is greater than 0 degrees and less than 90 degrees.

14. The absorbent article as claimed in claim 1 or 2, characterized in that: The outer portion of the core-sheath type composite fiber is melted.

15. The absorbent article as claimed in claim 14, characterized in that: The fiber diameter of the core-sheath type composite fiber relative to the portion of the fiber located outside the fiber orientation region in the front sheet is more than 40% and less than 80%.

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