Front sheet for absorbent article and absorbent article having the same

Abstract

The front sheet (10) for an absorbent article according to the present invention is formed of a fibrous material and has a plurality of through-holes (6). A valve film body (20) formed by membrane-forming the fibrous material is formed at a part of the opening end of the through-hole (6). The valve film body (20) can rotate about a part of the opening end of the through-hole (6) as an axis. The front sheet (10) has a convex portion (5) protruding toward one surface side of the front sheet (10) at a portion adjacent to the through-hole (6), and the valve film body (20) preferably extends from the bottom of the convex portion (5) toward the inside of the through-hole (6).

Description

Technical Field

[0001] The present invention relates to a front sheet for absorbent articles and an absorbent article having the same. Background Art

[0002] Absorbent articles such as disposable diapers generally have a front sheet that abuts against the skin of the wearer on the side opposite to the skin of the absorbent body having liquid retention properties. The present applicant previously disclosed a sheet that has a first non-woven fabric and a second non-woven fabric as the above-mentioned front sheet, and through-holes are formed in the welded portions formed by locally heat-welding and joining these two non-woven fabrics (Patent Documents 1 and 2).

[0003] Prior Art Documents

[0004] Patent Documents

[0005] Patent Document 1: Japanese Patent Application Laid-Open No. 2015-142721

[0006] Patent Document 2: Japanese Patent Application Laid-Open No. 2018-088997 Summary of the Invention

[0007] The present invention relates to a front sheet for absorbent articles formed of a fiber material and having a plurality of through-holes.

[0008] A valve film body formed by membrane-forming the fiber material is formed in a part of the opening end of the through-hole in the front sheet for absorbent articles.

[0009] The valve film body is preferably rotatable about a part of the opening end of the through-hole as an axis.

[0010] In addition, the present invention relates to an absorbent article having a front sheet for absorbent articles.

[0011] The absorbent article preferably includes a fiber sheet having a plurality of concave portions and convex portions disposed on the side opposite to the skin side of the front sheet for absorbent articles.

[0012] The absorbent article preferably has the through-holes and the valve film body in the front sheet for absorbent articles at least partially overlap with the concave portions in the fiber sheet. Brief Description of the Drawings

[0013] Figure 1 It is a view showing an embodiment of the front sheet for absorbent articles of the present invention, and is an enlarged plan view of the sheet as viewed from the first sheet side.

[0014] Figure 2 Is Figure 1 An end view of the shown front sheet along the Y direction.

[0015] Figure 3 IsFigure 1 Enlarged plan view of the through-hole shown.

[0016] Figure 4 For explaining Figure 1 Stereogram showing the effect of the valve film body shown.

[0017] Figure 5 Is Figure 2 Enlarged end view of the convex portion and the valve film body shown.

[0018] Figure 6 Is an enlarged plan view of the through-hole showing the deformation of the through-hole of the present invention.

[0019] Figure 7 Is an enlarged plan view of the skin-facing side (front sheet side) in the unfolded and stretched state of the unfolded disposable diaper showing an embodiment of the absorbent article of the present invention.

[0020] Figure 8 Is schematically showing Figure 7 Cross-sectional view of the cross-section taken along line II-II of

[0021] Figure 9 Is Figure 8 Enlarged end view of the front sheet and the sub-layer shown.

[0022] Figure 10 Is a schematic view showing an embodiment of the manufacturing apparatus for the front sheet.

[0023] Figure 11 Is Figure 10 Stereogram showing the main part of the embossed roller (first roller) shown in an enlarged manner.

[0024] Figure 12 Is showing the state of the main part of the ultrasonic welding machine shown when viewed from the upstream side in the conveying direction of the second sheet Figure 10 Front view of the main part.

[0025] Figure 13 Is showing Figure 10 View of the main part of the manufacturing apparatus shown (the front end portion of the ultrasonic horn and its vicinity).

[0026] Figure 14 Is Figure 13 Enlarged cross-sectional view schematically showing an enlarged cross-section of the front end portion of the ultrasonic horn shown along a direction (MD) orthogonal to the rotation axis of the embossed roller.

[0027] Figure 15 Is Figure 13 Plan view of the vibration application surface (front end surface) of the ultrasonic horn shown.

[0028] Figure 16 This is a diagram corresponding to another embodiment of the ultrasonic welding head of the present invention and Figure 14 the corresponding diagram.

[0029] Figure 17 This is a diagram corresponding to yet another embodiment of the ultrasonic welding head of the present invention and Figure 14 the corresponding diagram.

[0030] Figure 18 This is a diagram corresponding to yet another embodiment of the ultrasonic welding head of the present invention and Figure 14 the corresponding diagram.

[0031] Figure 19 (a) of is a diagram corresponding to yet another embodiment of the ultrasonic welding head of the present invention and Figure 14 the corresponding diagram, Figure 19 (b) of is a diagram schematically showing an enlarged view of the uneven portion shown in (a) of and its vicinity. Figure 19 the corresponding diagram. Detailed Embodiment

[0032] A structure in which a plurality of through-holes are provided in the front sheet is effective in improving the permeability of urine, soft feces, etc. However, even if excreta such as urine or soft feces move to the non-skin-facing side of the front sheet through the through-holes, the excreta remaining directly below the through-holes and the excreta returning to the skin-facing side of the front sheet through the through-holes may come into contact with the skin of the wearer of the absorbent article, and this excreta may contaminate the skin. On the other hand, if the through-holes are reduced to solve this problem, the permeability of the excreta may be lost. The front sheets described in Patent Documents 1 and 2 have room for improvement in terms of maintaining the permeability of excreta and suppressing contact between excreta and the skin.

[0033] Therefore, the present invention relates to a front sheet for an absorbent article that can maintain the permeability of excreta and can suppress contact with the skin, and an absorbent article having the same.

[0034] Hereinafter, the present invention will be described with reference to the accompanying drawings based on its preferred embodiments. In the following description of the drawings, the same or similar parts are denoted by the same or similar reference numerals. The drawings are basically schematic illustrations, and there are cases where the ratios of various dimensions, etc. are different from the actual ones.

[0035] Figure 1 and Figure 2 show the front sheet for an absorbent article (hereinafter, simply referred to as "front sheet 10") of the present embodiment. The front sheet 10 of the present embodiment is a fibrous sheet including a fibrous material and has through-holes 6 penetrating through the sheet.

[0036] The front sheet 10 has a laminated structure formed by laminating a first sheet 1 and a second sheet 2 made of a fiber material. These first sheet 1 and second sheet 2 are joined via a welded portion (not shown) that is welded to each other.

[0037] The first sheet 1 and the second sheet 2 are made of fiber sheets having a fiber material. As the fiber sheet, for example, non-woven fabric, woven fabric, knitted fabric, etc. can be used. From the viewpoint of skin feel, etc., it is preferable to use non-woven fabric. The types of fiber sheets constituting the first sheet 1 and the second sheet 2 may be the same or different.

[0038] As the non-woven fabric, for example, hot air non-woven fabric, spunbond non-woven fabric, hydroentangled non-woven fabric, meltblown non-woven fabric, resin-bonded non-woven fabric, needle-punched non-woven fabric, etc. can be cited. It is also possible to use a laminate in which two or more of these non-woven fabrics are combined.

[0039] The grammage of each of the first sheet 1 and the second sheet 2 is preferably 10 g / m 2 or more, more preferably 15 g / m 2 or more, and additionally preferably 40 g / m 2 or less, more preferably 35 g / m 2 or less, and additionally preferably 10 g / m 2 or more and 40 g / m 2 or less, more preferably 15 g / m 2 or more and 35 g / m 2 or less.

[0040] As the fiber constituting the non-woven fabric, fibers formed of various thermoplastic resins can be used.

[0041] As the thermoplastic resin, 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, alkyl poly(meth)acrylates, polyvinyl chloride, polyvinylidene chloride, etc. can be cited. These resins can be used alone or two or more can be used as a mixture. In addition, it can also be used in the form of composite fibers such as core-sheath type or side-by-side type.

[0042] The front sheet 10 of the present embodiment, as Figure 1 shown, has a plurality of convex portions 5 protruding toward one surface side of the front sheet 10 in a portion adjacent to the through-hole 6. Specifically, in at least a part of the portion of the first sheet 1 other than the through-hole 6, a plurality of convex portions 5 protruding toward the side opposite to the second sheet 2 side are formed.

[0043] The convex portions 5 and the through holes 6 are arranged alternately and in a row in one direction parallel to the surface of the front sheet 10, i.e., the X direction, and multiple rows are formed in the direction parallel to the surface of the front sheet 10 and orthogonal to the above-mentioned one direction, i.e., the Y direction. The convex portions 5 and the through holes 6 in adjacent rows are arranged offset from each other in the X direction, and more specifically, they are arranged offset by half a pitch.

[0044] In the front sheet 10 of the present embodiment, the Y direction is the direction parallel to the flow direction (machine direction, hereinafter also referred to as "MD") during manufacturing. The lateral Q direction in the absorbent article described later is the direction parallel to the direction orthogonal to the MD during manufacturing (hereinafter also referred to as "CD"). In addition, the rotation axes of the embossing roller 31 (first roller) and the embossing roller 32 (second roller) described later are parallel to the CD and orthogonal to the MD.

[0045] The front sheet 10 of the present embodiment has, on the surface on the first sheet 1 side, a plurality of concave portions 3 sandwiched by the convex portions 5 in both the X direction and the Y direction, and through holes 6 are formed at the bottoms of the respective concave portions 3.

[0046] When viewed as a whole, the front sheet 10 has large undulations formed by the above-mentioned concave portions 3 and the above-mentioned convex portions 5 on the surface on the first sheet 1 side, and the surface on the second sheet 2 side is flat or becomes a substantially flat surface with relatively smaller undulations compared to the surface on the first sheet 1 side.

[0047] In the front sheet 10 of the present embodiment, the convex portions 5 and the through holes 6 each have a top view shape that is longer in the Y direction (refer to Figure 1 ).

[0048] Each through hole 6 has a top view shape that is longer in the Y direction and is generally rectangular. The front sheet 10 has a welding portion (not shown) where the first sheet 1 and the second sheet 2 are welded to each other along a part of the opening end of the through hole 6 and outside the opening end. At this welding portion, the hot-melt resin of the constituent fibers of at least one of the first sheet 1 and the second sheet 2 is melted and solidified, whereby the first sheet 1 and the second sheet 2 are joined.

[0049] The front sheet 10 has a valve film body 20 at a part of the opening end of the through hole 6 in a top view. The valve film body 20 is not formed continuously around the entire circumference of the opening end of the through hole 6, but is formed at a part of the opening end of the through hole 6. In the through hole 6 of the present embodiment, as Figure 3 shown, there are a pair of valve film bodies 20a and 20b respectively located on both sides in the length direction (Y direction) of the through hole 6.

[0050] The valve film body 20 is connected to the first sheet 1 and the second sheet 2 at a part of the open end of the through-hole 6. With the connected part (a part of the open end of the through-hole 6) as the base end, it extends inward of the through-hole 6 in a plan view (refer to Figure 3 ).

[0051] The valve film body 20 becomes a film-like part formed by melting and solidifying the heat-fusible resin constituting the first sheet 1 and the second sheet 2. That is, in the valve film body 20, the fibrous materials constituting the first sheet 1 and the second sheet 2 do not maintain the fibrous form visually and are membranized in appearance.

[0052] The valve film body 20 can perform a hinge movement. Specifically, the valve film body 20 can rotate in the thickness direction Z of the front sheet 10 with a part of the open end of the through-hole 6 as an axis in the front sheet 10. As described above, the valve film body 20 is a membranized part formed by melting and solidifying the constituent fibers of the first sheet 1 and the second sheet 2, and the boundary between the membranized part and the non-membranized part (the part where the constituent fibers maintaining the fibrous form exist) is "a part of the open end" where the valve film body 20 is located. The base-end side edge of the valve film body 20 forms a part of the open end of the through-hole 6 and is connected to the first sheet 1 and the second sheet 2 at this part of the open end. Hereinafter, this base-end side edge will also be simply referred to as "the base-end edge part 21". The base-end edge part 21 is located at a part of the open end of the through-hole 6.

[0053] For example, when a load is applied to the valve film body 20 from the skin-facing side, the valve film body 20 rotates toward the non-skin-facing side with a part of the open end of the through-hole 6 as an axis. In addition, when the load applied to the valve film body 20 is released, the valve film body 20 that has rotated to the non-skin-facing side rotates toward the skin-facing side with a part of the open end of the through-hole 6 as an axis and returns to its original position.

[0054] The front sheet 10 is disposed on the skin-facing side of the absorbent body, which is a main liquid-absorbing part, in absorbent articles such as disposable diapers. The front sheet 10 abuts against the wearer's skin in the worn state of the absorbent article.

[0055] In this specification, the "skin-facing side" is the side of the absorbent article or its constituent parts (such as the absorbent body) that faces the wearer's skin side when the absorbent article is worn, that is, the side relatively closer to the wearer's skin, and the "non-skin-facing side" is the side of the absorbent article or its constituent parts that faces the opposite side (the clothing side) of the skin side when the absorbent article is worn, that is, the side relatively farther from the wearer's skin. Herein, the "when worn" refers to the state of maintaining the normal proper wearing position and does not include the case where the absorbent article is in a state deviated from the proper wearing position.

[0056] In the absorbent article having the front sheet 10 of the present embodiment, when urine or soft feces are excreted, these excrements move to the non-skin-facing side of the front sheet 10 through the through holes 6 in the front sheet 10. In this front sheet 10, when the excrement e reaches the valve film body 20 capable of performing a hinge action, the weight of the excrement e is applied to the valve film body 20. In addition, when the posture of the wearer changes, an external force greater than the weight of the excrement e is applied to the valve film body 20 due to body pressure. Due to the weight of the excrement e and body pressure (external force), the valve film body 20 rotates toward the non-skin-facing side of the front sheet 10, allowing the excrement e to smoothly move to the non-skin-facing side of the front sheet 10 (see Figure 4 ). In addition, when the excrement e moves to the non-skin-facing side of the front sheet 10, the valve film body 20 rotates back to its original position, becoming a state intervening between the excrement e on the non-skin-facing side and the skin, and can inhibit the contact of the excrement e with the skin (see Figure 4 ). Furthermore, even if the front sheet 10 is compressed in the thickness direction Z due to the body pressure of the wearer or the like, since the valve film body 20 is interposed, it is possible to inhibit the excrement e from returning to the skin-facing side of the front sheet 10. In this way, since the valve film body 20 functions as a check valve that allows the excrement e to move from the skin-facing side to the non-skin-facing side, the front sheet 10 can maintain the permeability of the excrement and inhibit the contact of the excrement with the skin.

[0057] The valve film body 20 in the front sheet 10 can be confirmed by observing the through hole 6 from either side of the front sheet 10 using an electron microscope (for example, manufactured by JEOL Ltd., model: JCM-6000Plus) or a microscope (for example, manufactured by KEYENCE CORPORATION, model: VHX-1000). When the front sheet 10 has a protruding convex portion 5 on a certain side, the through hole 6 is observed from the side opposite to the side where the convex portion 5 protrudes. The observation is performed at a magnification of 60 times. The valve film body 20 is a film-like region capable of performing a hinge action formed at a part of the opening end of the through hole 6, and is a region with an area of 1 mm 2 or more.

[0058] From the viewpoint of making the rotation of the valve film body 20 easier and making the movement of the excrement e toward the non-skin-facing side smoother, it is preferable that when a load is locally applied to the valve film body 20 from the skin-facing side, the entire valve film body 20 can rotate about a part of the opening end of the through hole 6. When the valve film body 20 has this structure, for example, assuming an imaginary line that bisects the entire length of the proximal end edge portion 21 and extends in the extending direction (Y direction) of the valve film body 20, even when a load is applied to any position on this imaginary line, the entire valve film body 20 rotates about a part of the above-mentioned opening end. In this way, it is preferable that even if the load applied to the valve film body 20 is local, the entire valve film body 20 can rotate.

[0059] The front sheet 10 of the present embodiment has a convex portion 5 at a portion adjacent to the through hole 6, and the valve film body 20 extends from the bottom of the convex portion 5 toward the inside of the through hole 6 (refer to Figure 4 and Figure 5 ). According to this structure, the excrement moves on the convex portion 5 and easily reaches the valve film body 20, so that the contact of the excrement with the skin can be more effectively suppressed. In the present embodiment, a second sheet 2 is formed at the bottom of the convex portion 5, and the non-skin-facing surface of the second sheet 2 is continuous with the non-skin-facing surface of the valve film body 20 in the planar direction.

[0060] The valve film body 20, as Figure 3 shown, has a free end edge portion 22 located on the opposite side of the proximal end edge portion 21, and a pair of side edge portions 23, 23 located between the proximal end edge portion 21 and the free end edge portion 22. When the valve film body 20 performs a hinge action, the free end edge portion 22 rotates about a part of the opening end of the through hole 6 so as to turn toward the skin-facing side or the non-skin-facing side.

[0061] From the viewpoint of making the hinge action of the valve film body 20 smoother, it is preferable that the pair of side edge portions 23, 23 are not connected to the opening end of the through hole 6 respectively. In other words, it is preferable that the pair of side edge portions 23, 23 are not continuous with the opening end of the through hole 6 respectively. In the present embodiment, the pair of side edge portions 23, 23 are not connected to the portions of the opening end of the through hole 6 that are opposite to the side edge portion 23 respectively (refer to Figure 3 ). According to this structure, since the movement of the valve film body 20 in the side edge portions 23, 23 is not restricted, when a load is applied to the skin-facing side or the non-skin-facing side, the rotation of the valve film body 20 about a part of the opening end of the through hole 6 becomes easier.

[0062] The side edge portions 23, 23 are the edges connected to both ends of the base edge portion 21 when the valve film body 20 is viewed from above, and are edges having an angle of 60 degrees or more with respect to the base edge portion 21. The free edge portion 22 is the edge that forms the front end of the valve film body 20 during its hinge action, and is an edge having an angle less than 60 degrees with respect to the angle of the base edge portion 21.

[0063] From the viewpoint of more comprehensively considering both the excrement permeability and the check valve function generated by the valve film body 20, it is preferable that the size of the valve film body 20 is within the following range.

[0064] The area of the valve film body 20 is preferably 5% or more, more preferably 10% or more, further preferably 50% or less, more preferably 40% or less, further preferably 5% or more and 50% or less, and more preferably 10% or more and 40% or less with respect to the area of the through hole 6.

[0065] The area of the through hole 6 is preferably 1 mm 2 or more, more preferably 2 mm 2 or more, further preferably 10 mm 2 or less, more preferably 5 mm 2 or less, further preferably 1 mm 2 or more and 10 mm 2 or less, more preferably 2 mm 2 or more and 8 mm 2 or less.

[0066] The area of the valve film body 20 is preferably 0.5 mm 2 or more, more preferably 1 mm 2 or more, further preferably 5 mm 2 or less, more preferably 2.5 mm 2 or less, further preferably 0.5 mm 2 or more and 5 mm 2 or less, more preferably 1 mm 2 or more and 2.5 mm 2 or less.

[0067] The area of the through hole 6 is the opening area when the valve film body 20 is removed from the through hole 6 and it is only the through hole 6. The area of the valve film body 20 is the area of each valve film body 20. Their areas are obtained as the average of the areas of 10 through holes 6 arbitrarily selected or the average of the areas of 10 valve film bodies 20 arbitrarily selected in a measurement piece (100 mm square) cut out from an arbitrary part of the front sheet 10.

[0068] The maximum length L of the valve film body 20 in the extending direction (Y direction) (refer to Figure 3The ratio (L / W1) with respect to the base end edge portion 21 is preferably 10% or more, more preferably 20% or more, further preferably 50% or less, more preferably 40% or less, further preferably 10% or more and 50% or less, and more preferably 20% or more and 40% or less.

[0069] The maximum length L of the valve film body 20 in the extending direction (Y direction) (refer to Figure 3 ) is preferably 1 mm or more, more preferably 2 mm or more, further preferably 5 mm or less, more preferably 4 mm or less, further preferably 1 mm or more and 5 mm or less, and more preferably 2 mm or more and 4 mm or less.

[0070] The length W1 of the base end edge portion 21 (refer to Figure 3 ) is preferably 1 mm or more, more preferably 2 mm or more, further preferably 10 mm or less, more preferably 5 mm or less, further preferably 1 mm or more and 10 mm or less, and more preferably 2 mm or more and 5 mm or less.

[0071] The length L6 in the length direction of the through hole 6 is preferably 1 mm or more, more preferably 2 mm or more, further preferably 15 mm or less, more preferably 10 mm or less, further preferably 1 mm or more and 15 mm or less, and more preferably 2 mm or more and 10 mm or less.

[0072] The length W6 in the direction orthogonal to the length direction of the through hole 6 is preferably 1.5 mm or more, more preferably 2.5 mm or more, further preferably 11 mm or less, more preferably 6 mm or less, further preferably 1.5 mm or more and 11 mm or less, and more preferably 2.5 mm or more and 6 mm or less.

[0073] The front sheet 10 of the present embodiment, as Figure 3 shown, has a pair of valve film bodies 20a and 20b disposed opposite to each other on both sides in the length direction (Y direction) of the through hole 6. The shapes of this pair of valve film bodies 20a and 20b are different from each other. Specifically, one valve film body 20a is a curved shape in which the free end edge portion 22 is convexly bent toward the inside of the through hole 6, while the free end edge portion 22 of the other valve film body 20b is a serrated wave shape.

[0074] From the viewpoint of making the hinge action smoother and further improving the function of the check valve by the valve film body 20, it is preferable that the free end edge portion 22 has a wave shape in a plan view. In this form, it becomes a concavo-convex shape in which the positions forming the contour line of the free end edge portion 22 alternately change toward the side closer to the base end edge portion 21 and the side away from the base end edge portion 21.

[0075] From the same viewpoint as described above, the zigzag length L2 (not shown) of the free end edge portion 22 and the length W1 of the base end edge portion 21 are preferably within the following ranges.

[0076] The ratio (L2 / W1) of the zigzag length L2 of the free end edge portion 22 to the length W1 of the base end edge portion 21 is preferably greater than 1, more preferably 2 or more, and preferably less than 10, more preferably 5 or less. Additionally, it is preferably greater than 1 and less than 10, more preferably 2 or more and 5 or less.

[0077] The zigzag length L2 of the free end edge portion 22 is measured, for example, by performing image processing on an electron microscope image of the valve film body 20 in a plan view. In this image processing, the measurement menu for the distance between multiple points that is default installed in the software named "KEYENCE VHX-1000" is used. For example, in an electron microscope image (magnification: 60 times), by performing an operation of tracing and depicting the free end edge portion 22, the zigzag length (the length of meandering forward) L2 of the free end edge portion 22 can be measured.

[0078] When the free end edge portion 22 has a wave shape in a plan view, the contour line forming the free end edge portion 22 in the valve film body 20b becomes an uneven shape. When looking at the valve film body 20b having the free end edge portion 22 along the length direction (X direction) of the base end edge portion 21, the concave portions and the convex portions are alternately arranged to form a wave shape. The number of vertices of the convex portions in the valve film body 20b is preferably 2 or more and 20 or less, more preferably 5 or more and 10 or less. When the number of vertices of the convex portions is within such a range, each convex portion functions as one valve, so the check valve function of the valve film body 20b can be further improved. On the other hand, when the number of vertices of the convex portions is too large, since the unevenness of the free end edge portion 22 is too fine, it is difficult for each convex portion in the valve film body 20 to function as one valve.

[0079] The number of vertices of the convex portions in the valve film body 20b having a wave-shaped free end edge portion 22 is obtained by the following method. First, for each convex portion in the valve film body 20b, the degree of protrusion La of the convex portion is obtained by the following formula.

[0080] La = {(L10 - L11) + (L10 - L12)} / 2

[0081] L10: The separation distance between the vertex of the convex portion and the base end edge portion 21

[0082] L11: The separation distance between the bottom of the concave portion adjacent to the convex portion and the base end edge portion 21

[0083] L12: The separation distance between the bottom of the concave portion on the other side adjacent to the convex portion and the base end edge portion 21

[0084] Next, count the number of convex portions whose protruding degree La with respect to the length L6 in the length direction of the through-hole 6 exceeds 5%. In addition, when viewed along the length direction of the base end edge portion 21, count including the convex portions located at both ends in this direction. The total number of convex portions counted in this way is taken as the "number of vertices of the convex portions".

[0085] The above-mentioned separation distances L10, L11, L12 (refer to Figure 3 ) are measured, for example, by performing the above-mentioned image processing (length measurement menu for distances between multiple points) on the electron microscope image of the valve film body 20 in a plan view. For example, in the electron microscope image (magnification: 60 times), perform the operation of selecting the vertices of the convex portions and the base end edge portion 21 that constitute the concavo-convex shape of the free end edge portion 22, whereby the separation distance between the vertices of the convex portions and the base end edge portion 21 can be measured.

[0086] The thickness of the valve film body 20 can be a constant value or can vary according to the position.

[0087] From the viewpoint of more reliably obtaining the strength of the valve film body 20, the minimum thickness t1 of the valve film body 20 (refer to Figure 5 ) is preferably 10 μm or more, more preferably 20 μm or more, and preferably 1 mm or less, more preferably 500 μm or less. Additionally, it is preferably 10 μm or more and 1 mm or less, more preferably 20 μm or more and 500 μm or less.

[0088] From the viewpoints of making the hinge movement toward the non-skin facing side smoother, further improving the excrement permeability, and further suppressing the contact of excrement with the skin, the valve film body 20 preferably has a large thickness portion 25 (refer to Figure 5 ) with a larger thickness than other portions on the base end edge portion 21 side. The "base end edge portion 21 side" is the region on the base end edge portion 21 side when the entire length in the extending direction of the valve film body 20 is bisected into two regions, and preferably, when the entire length in the extending direction of the valve film body 20 is trisected into three regions, it is the region closest to the base end edge portion 21. More preferably, the valve film body 20 has a large thickness portion 25 at a position adjacent to the base end edge portion 21.

[0089] As a form having a large thickness portion 25 on the base end edge portion 21 side, examples can be given such as a form in which the thickness gradually increases from the free end edge portion 22 toward the base end edge portion 21 in the cross-section in the extending direction of the valve film body 20, or a form in which there is a portion where the thickness locally becomes larger at one end portion on the base end edge portion 21 side, etc.

[0090] Based on the same viewpoints as above, the maximum thickness t2 of the large thickness portion 25 (refer to Figure 5) is within the following range. The maximum thickness of the thick portion 25 is equivalent to the maximum thickness of the valve film body 20.

[0091] The minimum thickness t1 of the valve film body 20 (refer to Figure 5 ) with respect to the maximum thickness t2 of the thick portion 25 (t1 / t2) (refer to Figure 5 ) is preferably 0.5% or more, more preferably 1% or more, further preferably 10% or less, more preferably 5% or less, further preferably 0.5% or more and 10% or less, more preferably 1% or more and 5% or less.

[0092] The maximum thickness t2 of the thick portion 25 (refer to Figure 5 ) is preferably 20 μm or more, more preferably 200 μm or more, further preferably 1.1 mm or less, more preferably 600 μm or less, further preferably 20 μm or more and 1.1 mm or less, more preferably 200 μm or more and 600 μm or less.

[0093] The minimum thickness t1 of the valve film body 20 and the thickness t2 of the thick portion 25 are measured by the following method. First, along the extending direction of the valve film body 20, that is, along the direction from the base end edge portion 21 to the free end edge portion 22, use a blade or the like to cut the front sheet 10 through the through hole 6 and the valve film body 20. When cutting the front sheet 10, make the cutting line generated by this cutting extend in one direction (for example, the Y direction) through the vertex of the convex portion 5. When significant deformation such as concavo-convex structure occurs due to the pressure of the blade during cutting, immerse the front sheet 10 in liquid nitrogen and then quickly cut. Then, observe the cut surface with an electron microscope (magnification 200 times), and measure the minimum thickness of the valve film body 20 and the thickness of the thick portion 25. Perform this measurement on 10 valve film bodies 20, and take the average value as the minimum thickness of the valve film body 20 and the thickness of the thick portion 25.

[0094] As described above, the front sheet 10 of the present embodiment has a through hole 6 that is long in the Y direction and has valve film bodies 20a and 20b with different shapes from each other. The shapes of the through hole 6 and the valve film body 20 are not limited to this. In Figure 6 (a) to (j), deformations of the through hole 6 and the valve film body 20 are shown.

[0095] Figure 6 The through hole 6 shown in (a) to (e) of Figure 6 has a rectangular shape that is long in the Y direction. Figure 6 The through hole 6 shown in (f) to (h) of

[0096] has an elliptical shape that is long in the X direction or the Y direction. Figure 6In the forms shown in (a), (c), (f), and (i), there is a single valve film body 20 in one through-hole 6. In Figure 6 In the forms shown in (b), (d), (e), (g), (h), and (j), there are two or more valve film bodies 20 in one through-hole 6.

[0097] In Figure 6 In the forms shown in (b), (d), (e), (g), and (h), the multiple valve film bodies 20 have the same shape. On the other hand, in Figure 6 In the form shown in (j), the multiple valve film bodies 20 have different shapes.

[0098] In Figure 6 In the forms shown in (b), (g), (h), and (j), a pair of valve film bodies 20 are oppositely arranged on both sides in the longitudinal direction (Y direction or X direction) of the through-hole 6. In Figure 6 In the forms shown in (d) and (e), a pair of valve film bodies 20 are oppositely arranged on both sides in the direction (X direction) orthogonal to the longitudinal direction of the through-hole 6.

[0099] In Figure 6 In the forms shown in (a) and (e), the free end edge portion 22 of the valve film body 20 has a wavy line shape. On the other hand, in Figure 6 In the forms shown in (b), (c), (f), (g), and (h), the free end edge portion 22 of the valve film body 20 has a straight line shape along the base end edge portion 21 or a curved shape that bends in a direction away from the base end edge portion 21.

[0100] The valve film body 20 can be formed in all the through-holes 6 in the front sheet 10 or in a part of the through-holes 6.

[0101] 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 which the valve film body 20 is formed per unit area (the area of a 10 mm square region in plan view) in the front sheet 10 is preferably 30% or more, more preferably 50% or more, and further preferably the valve film body 20 is formed in all the through-holes 6, in all the through-holes 6.

[0102] From the same viewpoint as above, in the front sheet 10, the number of through-holes 6 in which the valve film body 20 is formed per unit area (the area of a 10 mm square region in plan view) is preferably 1 or more, more preferably 4 or more, and preferably 20 or less, more preferably 15 or less.

[0103] From the viewpoints of the skin feel and the cushioning property, the front sheet 10 of the present embodiment preferably has the following structure.

[0104] The height H of the convex portion 5 (refer to Figure 5 ) is preferably 1 mm or more, more preferably 3 mm or more, further preferably 10 mm or less, more preferably 6 mm or less, further preferably 1 mm or more and 10 mm or less, and more preferably 3 mm or more and 6 mm or less.

[0105] The number of the convex portions 5 per unit area (1 cm 2 ) of the front sheet 10 is preferably 1 or more, more preferably 6 or more, further preferably 20 or less, more preferably 15 or less, further preferably 1 or more and 20 or less, and more preferably 6 or more and 15 or less.

[0106] The bottom area of the convex portion 5 is preferably 0.5 mm 2 or more, more preferably 2 mm 2 or more, further preferably 50 mm 2 or less, more preferably 20 mm 2 or less, further preferably 0.5 mm 2 or more and 50 mm 2 or less, more preferably 2 mm 2 or more and 20 mm 2 or less.

[0107] The front sheet 10 of the present embodiment is preferably used as the front sheet of absorbent articles such as disposable diapers, sanitary napkins, pantiliners, incontinence pads and the like. In particular, in the front sheet 10, it is preferable that the first sheet 1 forms the surface (skin-facing surface) facing the wearer's skin and the second sheet 2 forms the surface (non-skin-facing surface) facing the absorbent body side during wearing.

[0108] Hereinafter, absorbent articles having the front sheet for absorbent articles of the present invention will be described based on their preferred embodiments. In Figure 7 and Figure 8 , an unfolded disposable diaper 11 is shown as an embodiment of the absorbent article of the present invention. The diaper 11 has the structure of the front sheet 10 of the above-described embodiment. The diaper 11 has a longitudinal direction P corresponding to the front-back direction of the wearer and a lateral direction Q orthogonal thereto, an absorbent body 14 having liquid retention property, and a front sheet 10 disposed on the skin side of the wearer with respect to the absorbent body 14.

[0109] The diaper 11 is as shown in Figure 7As shown, it has a crotch portion B disposed at the crotch of the wearer, and a ventral portion A and a dorsal portion C extending forward and backward therefrom. The ventral portion A, the crotch portion B, and the dorsal portion C can correspond to respective regions when the diaper 11 is trisected in the longitudinal direction P. The crotch portion B has an excretion portion facing portion that is disposed opposite to excretion portions such as the penis and anus of the wearer when the diaper 11 is worn, and this excretion portion facing portion is usually located at the central portion of the longitudinal direction P of the diaper 11 or in its vicinity.

[0110] In the diaper 11, as Figure 8 shown, in order from closest to the skin of the wearer to farthest therefrom, a front sheet 10, a liquid-permeable sub-layer 15, and a liquid-retaining absorbent body 14 are laminated in sequence. More specifically, the diaper 11 includes: an absorbent body 14; a front sheet 10 disposed on the skin-facing side of the absorbent body 14 and overlapping the absorbent body 14 at a position closer to the skin of the wearer than the absorbent body 14; a back sheet 13 disposed on the non-skin-facing side of the absorbent body 14 and overlapping the absorbent body 14 at a position farther from the skin of the wearer than the absorbent body 14; and a sub-layer 15 disposed between the front sheet 10 and the absorbent body 14.

[0111] The front sheet 10 and the back sheet 13 each have a size larger than that of the sub-layer 15 and the absorbent body 14 disposed between the two sheets 10 and 13, forming the outer shape of the diaper 11 in an unfolded and elongated state as Figure 7 shown.

[0112] The absorbent body 14 has a shape that is long in the longitudinal direction P and extends from the ventral portion A to the dorsal portion C. The absorbent body 14 includes a liquid-retaining absorbent core 140 and a wrapper sheet 141 that covers the outer surface of the absorbent core 140. The absorbent core 140 typically includes an aggregate of hydrophilic fibers such as wood pulp, and furthermore, it can also be a structure in which water-absorbing polymer particles are supported on the fiber aggregate. The wrapper sheet 141 is typically formed of paper, non-woven fabric, or the like.

[0113] As the back sheet 13, various sheets that have been conventionally used in such absorbent articles can be used without particular limitation, and a resin film, a laminate of a resin film and non-woven fabric, or the like can be used.

[0114] The diaper 11 of the present embodiment has a sub-layer 15 as a fiber sheet disposed on the non-skin-facing side of the front sheet 10. Since the sub-layer 15 is a layer that functions to improve the liquid permeability from the front sheet 10 to the absorbent body 14 and reduce the backflow of the liquid absorbed by the absorbent body 14 to the front sheet 10, it covers substantially the entire region of the skin-facing surface of the absorbent body 14.

[0115] The front sheet 10, the sub-layer 15, the absorbent body 14 (the absorbent core 140, the wrapper sheet 141), and the back sheet 13 are joined to each other by a known joining method such as an adhesive.

[0116] The sub-layer 15 of the present embodiment has a plurality of concave portions 151 and convex portions 152. Specifically, the sub-layer 15 has a plurality of convex portions 152 that protrude toward the skin-facing side and are hollow inside, and concave portions 151 located between the plurality of convex portions 152. The non-skin-facing side of the sub-layer 15 has an uneven shape corresponding to the uneven shape of the skin-facing side.

[0117] The plurality of concave portions 151 and convex portions 152 in the sub-layer 15 are alternately and continuously arranged along the longitudinal direction P and the lateral direction Q. The sub-layer 15 includes a plurality of convex portions 152 that protrude toward the skin-facing side and have an internal space, and concave portions 151 located between the plurality of convex portions 152, and includes a plurality of non-skin-side convex portions 153 that protrude toward the non-skin-facing side and have an internal space, and non-skin-side concave portions 154 located between the plurality of non-skin-side convex portions 153. The uneven shape on the skin-facing side formed by the convex portions 152 and the concave portions 151 in the sub-layer 15 corresponds to the uneven shape on the non-skin-facing side formed by the non-skin-side convex portions 153 and the non-skin-side concave portions 154 in the sub-layer 15. As the sub-layer 15 having this structure, for example, an intermediate sheet described in Japanese Patent Application Laid-Open No. 2019-97678 can be used.

[0118] From the viewpoint of further improving the mobility of excrement toward the absorber 14, it is preferable that the through-holes 6 and the valve film body 20 of the front sheet 10 at least partially overlap with the concave portions 151 in the sub-layer 15 (refer to Figure 9 ). Thereby, the excrement passing through the through-hole 6 easily enters the concave portion 151 of the sub-layer 15.

[0119] From the viewpoint of further improving the above effects, the depth of the concave portion 151 in the sub-layer 15 is preferably 0.5 mm or more, more preferably 1 mm or more, and preferably 5 mm or less, more preferably 3 mm or less, and preferably 0.5 mm or more and 5 mm or less, more preferably 1 mm or more and 3 mm or less. The depth of the concave portion 151 is measured by microscopic observation of a cross-section in the thickness direction of the sub-layer 15 under no load.

[0120] As the sub-layer 15, a hydrophilic and liquid-permeable sheet can be used. Specifically, paper, woven fabric, and non-woven fabric can be exemplified, and non-woven fabric is particularly preferable in terms of having relatively high strength and excellent softness. In addition, although the sub-layer 15 in the present embodiment has a single-layer structure, instead of this structure, the sub-layer 15 may have a multi-layer structure formed by laminating a plurality of layers. Further, the concavo-convex shape in the sub-layer 15 can adopt, for example, a conical shape such as a cone, a frustum of a cone, a pyramid, a frustum of a pyramid, or an oblique cone. The sub-layer 15 having the concavo-convex shape can be manufactured, for example, by disposing a raw material non-woven fabric (e.g., a hot air non-woven fabric) on a support having a plurality of protrusions and then blowing hot air onto the raw material non-woven fabric or the like on the support to form the concavo-convex shape. As a method for manufacturing the sub-layer 15, methods described in, for example, JP-A-2013-133574, JP-A-2012-149370, and JP-A-2012-149371 can be exemplified.

[0121] The diaper 11 is as Figure 7 and Figure 8 shown, and has a pair of leak-proof flanges 16, 16 which are disposed along both ends in the transverse direction Q of the absorbent body 14 and stand up against the wearer's skin at least in the crotch portion B when the diaper 11 is worn. Each leak-proof flange 16 includes a leak-proof sheet 160 having liquid resistance or water repellency and air permeability. One end side in the transverse direction Q of the leak-proof sheet 160 is fixed to another member (e.g., a front sheet or a back sheet) to form a fixed end portion, and the other end side in the transverse direction Q is formed as a free end portion that is not fixed to the other member. At the free end portion of the leak-proof sheet 160, an elastic member 161 for forming the leak-proof flange is fixed in an extended state in the longitudinal direction P so as to be stretchable in this direction. When the diaper 11 is worn, due to the contraction force of the elastic member 161, at least in the crotch portion B, the free end portion side of the leak-proof sheet 160 stands up toward the wearer side with the fixed end portion as a standing base end, so that the pair of leak-proof flanges 16, 16 stand up, thereby preventing excrement such as urine from flowing out to the outside in the transverse direction Q. As the leak-proof sheet 160, a material used as a material for the leak-proof flange in such an absorbent article can be used without particular limitation, and a material having liquid resistance or water repellency and air permeability is preferable. For example, a single-layer or multi-layer water-repellent non-woven fabric, a laminate of a resin film and a non-woven fabric, or the like can be used.

[0122] As Figure 7 shown, a linear elastic member 17 is fixed in an extended state along the longitudinal direction P between the leak-proof sheets 160 and the back sheet 13 of the left and right legs disposed around the wearer's legs. Thus, at the legs when the diaper 11 is worn, a pair of leg wrinkles are formed by the contraction of the elastic member 17. The front sheet 10, the sub-layer 15, the back sheet 13, the absorbent body 14, the leak-proof sheet 160, and the elastic member 161 are joined to each other by a known joining method such as a hot melt adhesive.

[0123] As Figure 7 shown, a pair of hook-and-loop fasteners 18, 18 are provided on both side edges along the longitudinal direction P of the dorsal part C of the diaper 11. A fixing part formed of the male surface member of a mechanical surface fastener is attached to the hook-and-loop fastener 18. In addition, a fixed region 19 formed of the female surface member of a mechanical surface fastener is formed on the non-skin-facing surface of the ventral part A of the diaper 11. The fixed region 19 is formed by joining and fixing the female surface member of the mechanical surface fastener to the non-skin-facing surface of the back sheet 13 forming the non-skin-facing surface of the ventral part A by a known joining method, such as an adhesive, heat sealing, etc., and is configured to be able to detachably fix the above-mentioned fixing part of the hook-and-loop fastener 18.

[0124] Next, regarding the manufacturing method of the front sheet for the absorbent article of the present invention, the manufacturing method of the front sheet 10 of the above-described embodiment will be described as an example. In Figure 10 FIG. shows a manufacturing apparatus 100 as an embodiment of the manufacturing apparatus for the front sheet of the absorbent article of the present invention. The manufacturing apparatus 100 has a concavo-convex shaping part 30 and an ultrasonic treatment part 40.

[0125] The concavo-convex shaping part 30 includes a concavo-convex roller 31 having concavities and convexities on its peripheral surface. In the concavo-convex shaping part 30, the first sheet 1 follows the peripheral surface of the rotating concavo-convex roller 31, thereby deforming the first sheet 1 into a concavo-convex shape along the concavities and convexities of the peripheral surface.

[0126] The concavo-convex shaping part 30 further has another concavo-convex roller 32 in addition to the concavo-convex roller 31, and the another concavo-convex roller 32 has concavities and convexities that engage with the concavities and convexities of the concavo-convex roller 31 on its peripheral surface.

[0127] Hereinafter, the concavo-convex roller 31 will be referred to as the "first roller", and the concavo-convex roller 32 will be referred to as the "second roller".

[0128] In Figure 10 the concavo-convex shaping part 30 shown, using these two rollers 31, 32, the two rollers 31, 32 are rotated in such a way as to form an engaging part 33 between the concavities and convexities of the two rollers 31, 32, and the first sheet 1 is introduced into the engaging part 33, thereby deforming the first sheet 1 into a concavo-convex shape along the concavities and convexities of the peripheral surface of the concavo-convex roller 31.

[0129] In Figure 11 FIG. shows a part of the peripheral surface of the concavo-convex roller 31 (first roller).

[0130] The uneven roller 31 is structured by combining multiple spur gears 31a, 31b, …… with a specified tooth width into a roller shape. The teeth of each gear form convex portions 35 of the uneven shape on the circumferential surface portion of the uneven roller 31, and a pressure surface for pressing the first and second sheets 1 and 2 to be welded is formed between the front end surface 35c of the convex portion 35 and the front end surface of the ultrasonic horn 42 of the ultrasonic welding machine 41 described later, that is, the vibration application surface 42t.

[0131] The tooth width (the length in the axial direction of the gear) of each gear constituting the uneven roller 31 determines the dimension in the X direction of the convex portion 5 of the front sheet 10, and the length of the tooth of each gear (the length in the rotational direction of the gear) determines the dimension in the Y direction of the convex portion 5 of the front sheet 10.

[0132] Adjacent gears are combined in such a way that the pitch of their teeth is offset by half a pitch each. As a result, the circumferential surface portion of the uneven roller 31 becomes an uneven shape.

[0133] In the illustrated manner, the front end surface 35c of each convex portion 35 is formed into a rectangular shape with the rotational direction of the uneven roller 31 as the long side and the axial direction as the short side.

[0134] When the front end surface 35c is a shape that is longer in the rotational direction, the contact time between one convex portion 35 of the uneven roller 31 and the vibration application surface 42t of the front end portion of the ultrasonic horn 42 becomes longer, and the temperature can rise easily, so this is preferable.

[0135] The depressions of the gears in the uneven roller 31 form the concave portions of the unevenness on the circumferential surface portion of the uneven roller 31.

[0136] Suction holes 34 are formed at the bottom of the teeth (the bottom of the depressions) of each gear. The suction holes 34 are controlled in such a way that suction is performed from the meshing portion 33 between the uneven roller 31 and the uneven roller 32 to between the confluence portions of the first sheet 1 and the second sheet 2 through a suction source (not shown) such as a blower or a vacuum pump.

[0137] Thus, the first sheet 1 deformed into an uneven shape by the meshing of the uneven roller 31 and the uneven roller 32 is transported to the confluence portion of the first sheet 1 and the second sheet 2 and the ultrasonic vibration application portion 36 of the ultrasonic welding machine 41 while maintaining the state of being deformed along the unevenness of the circumferential surface portion of the uneven roller 31 due to the suction force via the suction holes 34.

[0138] At Figure 11 In the illustrated uneven roller 31, a specified gap G is provided between adjacent gears, whereby it is possible to suppress the occurrence of an unreasonable elongation force being applied to the first sheet 1 or the first sheet 1 being cut by the meshing portion 33 of the two rollers 31 and 32. Therefore, the first sheet 1 is easily deformed into an uneven shape along the shape of the circumferential surface portion of the uneven roller 31.

[0139] The uneven roller 32 (the second roller) has an uneven shape on its circumferential surface that meshes with the unevenness of the circumferential surface of the uneven roller 31. The uneven roller 32 has the same structure as the uneven roller 31 except that it does not have the suction holes 34.

[0140] In addition, on the premise that the uneven portions of the two rollers 31 and 32 mesh with each other, the diameters of the uneven roller 31 and the uneven roller 32 can be different. By rotating the two rollers 31 and 32 having unevenness that meshes with each other while introducing the first sheet 1 into the meshing portion 33 of the two rollers 31 and 32, the first sheet 1 can be deformed into an uneven shape.

[0141] In the meshing portion 33, multiple portions of the first sheet 1 are pressed by the convex portions of the uneven roller 32 into the concave portions of the circumferential surface of the uneven roller 31, and the pressed portions become the convex portions 5 of the manufactured front sheet 10.

[0142] Multiple convex portions that are inserted into the concave portions of the uneven roller 31 are formed on the circumferential surface of the uneven roller 32, but it is not necessary for the uneven roller 32 to form convex portions corresponding to all the concave portions of the uneven roller 31.

[0143] In addition, Figure 10 As described above, the uneven shaping portion 30 shown includes two uneven rollers having unevenness on their circumferential surfaces. The two rollers 31 and 32 are rotated so as to form the meshing portion 33 between the unevenness of the two uneven rollers 31 and 32, and the first sheet 1 is introduced into the meshing portion 33, whereby the first sheet 1 is deformed into an uneven shape. However, the uneven roller included in the uneven shaping portion 30 may also be only the uneven roller 31 that can suck and guide the first sheet 1 introduced to the circumferential surface, that is, the uneven roller 32 may not be provided. In this case, as long as the first sheet 1 is introduced into the circumferential surface of the uneven roller 31, the suction force generated by the suction holes 34 (refer to Figure 11 ) provided on the circumferential surface can be used to deform the first sheet 1 in a shape following the unevenness of the circumferential surface. Such following and deformation of the first sheet 1 by suction at the circumferential surface of the uneven roller 31 can be achieved by appropriately adjusting the suction force, the arrangement of the suction holes 34, etc.

[0144] The ultrasonic treatment portion 40 includes an ultrasonic welder 41 having an ultrasonic horn 42. The second sheet 2 is overlapped on the first sheet 1 deformed into an uneven shape, and the two sheets 1 and 2 are clamped between the convex portion 35 of the uneven roller 31 and the vibration application surface 42t at the front end of the ultrasonic horn 42 and ultrasonic vibration is applied, thereby forming a through hole 6 and welding the first sheet 1 and the second sheet 2. At this time, a welded portion where the first sheet 1 and the second sheet 2 are welded and the valve film body 20 are formed at the peripheral edge portion (opening portion) of the through hole 6.

[0145] The ultrasonic welder 41 is as Figure 10 and Figure 12As shown, it has an ultrasonic oscillator (not shown), a converter 43, a horn 44, and an ultrasonic welding head 42.

[0146] The ultrasonic oscillator (not shown) is electrically connected to the converter 43, and a high-voltage electrical signal with a wavelength in the range of 15 - 50 kHz generated by the ultrasonic oscillator is input to the converter 43.

[0147] The ultrasonic oscillator (not shown) is provided on or outside the movable table 45.

[0148] The converter 43 incorporates a piezoelectric element such as a piezo piezoelectric element, and converts the electrical signal input from the ultrasonic oscillator into mechanical vibration through the piezoelectric element. The horn 44 adjusts, preferably amplifies, the amplitude of the mechanical vibration generated by the converter 43 and transmits it to the ultrasonic welding head 42.

[0149] The ultrasonic welding head 42 is formed of a block of metal such as aluminum alloy or titanium alloy, and is designed to resonate appropriately at the frequency of use.

[0150] The ultrasonic vibration transmitted from the horn 44 to the ultrasonic welding head 42 is also amplified or attenuated inside the ultrasonic welding head 42 and applied to the first and second sheets 1 and 2 to be welded. As this ultrasonic welding machine 41, commercially available ultrasonic welding heads, converters, horns, and ultrasonic oscillators can be combined and used.

[0151] The ultrasonic welding machine 41 is fixed to the movable table 45, and the position of the movable table 45 is advanced and retracted along the direction approaching the circumferential surface of the uneven roller 31, whereby the gap between the vibration application surface 42t of the front end surface of the ultrasonic welding head 42 and the front end surface 35c of the convex portion 35 of the first roller 31, and the pressing force on the stacked first and second sheets 1 and 2 can be adjusted.

[0152] The first and second sheets 1 and 2 to be welded are sandwiched between the front end surface 35c of the convex portion 35 of the uneven roller 31 and the vibration application surface 42t of the front end portion of the ultrasonic welding head 42 of the ultrasonic welding machine 41 and pressed, and ultrasonic vibration is applied to the two sheets 1 and 2, whereby the portion of the two sheets 1 and 2 located on the front end surface 35c of the convex portion 35 generates heat. As a result, the first sheet 1 and / or the second sheet 2 melts and is re-solidified to form a molten portion, and a through hole 6 penetrating the two sheets 1 and 2 is surrounded by this molten portion. This molten portion becomes a welded portion along a part of the opening end of the through hole 6. In addition, it is considered that a valve film body 20 is formed by a part of this molten portion using a shearing force described later.

[0153] The vibration application surface 42t of the front end portion of the ultrasonic welding head 42 is formed of the main body portion 420 of the ultrasonic welding head 42 formed of metal such as aluminum alloy or titanium alloy (refer to Figure 12) is formed by the front end surface and abuts against the welding object, more specifically, against the second sheet 2.

[0154] The manufacturing apparatus 100 includes a preheating member 51 that preheats at least one of the first sheet 1 and the second sheet 2 before ultrasonic vibration is applied.

[0155] The preheating member 51 is disposed inside the uneven roller 31 (first roller) and extends parallel to the rotation axis (CD) of the uneven roller 31.

[0156] In addition, a plurality of preheating members 51 are arranged at intervals in the circumferential direction near the outer peripheral portion around the rotation axis of the uneven roller 31.

[0157] As the preheating member 51, a mechanism that applies heat energy to the heating object (the first sheet 1, the second sheet 2) from the outside can be used. For example, a cartridge heater using a heating wire can be cited, but it is not limited thereto, and various known heating mechanisms can be used without particular limitation.

[0158] The preheating member 51 is a part of the preheating mechanism 50.

[0159] In addition to the preheating member 51, the preheating mechanism 50 includes a temperature measuring mechanism (not shown) that can measure the temperature of the welding object before ultrasonic vibration is applied, and a temperature control unit (not shown) that controls the temperature of the preheating member 51 based on the measured value of the temperature measuring mechanism.

[0160] The heating temperature of the peripheral surface portion of the uneven roller 31 by the preheating member 51 is controlled by the temperature control unit. By the preheating mechanism 50, the temperature of the first sheet 1 introduced into the ultrasonic vibration application portion 36 during the operation of the manufacturing apparatus 100 can be maintained within a specified range.

[0161] The manufacturing apparatus 100 is as Figure 13 shown, and includes a horn heating member 61 that heats the ultrasonic horn 42 including the vibration application surface 42t.

[0162] The horn heating member 61 is not disposed on the vibration application surface 42t, but is fixed near the vibration application surface 42t, specifically, on the side surface of the front end portion of the ultrasonic horn 42.

[0163] As the horn heating member 61, various known heating mechanisms such as a heater can be used without particular limitation.

[0164] The horn heating member 61 is a part of the horn heating mechanism 60.

[0165] In addition to the tip heating member 61, the tip heating mechanism 60 further 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 tip heating member 61 based on the measurement value of the temperature measuring mechanism.

[0166] The heating temperature of the vibration application surface 42t of the tip heating member 61 is controlled by the above temperature control unit. The tip 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.

[0167] In addition, the ultrasonic welder 41 is a device that applies ultrasonic vibration to the welding object, thereby heating and melting the welding object for welding, and is clearly distinguished from the above-mentioned preheating member 51 and tip heating member 61.

[0168] In the manufacturing apparatus 100, a groove-shaped recess 46 is formed in the vibration application surface 42t of the ultrasonic tip 42. Figure 14 FIG. shows a schematic cross-sectional view along the MD of the tip portion of the ultrasonic tip 42. Figure 15 FIG. shows a schematic plan view of the vibration application surface 42t of the ultrasonic tip 42. Figure 14 is Figure 13 An enlarged cross-sectional view of the tip portion of the ultrasonic tip 42 shown in FIG.

[0169] The groove-shaped recess 46 extends along the rotation axis (CD) of the uneven roller 31 (first roller). Here, the expression "extends along the rotation axis (CD)" means that the angle formed by the groove-shaped recess 46 and the rotation axis (CD) of the uneven roller 31 is less than 45 degrees. Figure 15 The groove-shaped recess 46 shown in FIG. extends parallel to the rotation axis (CD) and forms an angle of zero with the rotation axis (CD).

[0170] In the manufacturing apparatus 100, one groove-shaped recess 46 is formed in the vibration application surface 42t. As shown in Figure 15 FIG., the one groove-shaped recess 46 is located at the center of the length of the vibration application surface 42t along the MD and extends over the entire length along the CD.

[0171] The groove-shaped recess 46 is defined by a pair of recess side surfaces 46a, 46a and a recess bottom surface 46b in a cross-sectional view along the direction (i.e., MD) orthogonal to the rotation axis of the uneven roller 31 as shown in Figure 14 FIG.

[0172] The pair of recess side surfaces 46a, 46a intersect the vibration application surface 42t. More specifically, they are connected to the vibration application surface 42t and extend in a direction away from the vibration application surface 42t.

[0173] The bottom surface 46b of the recess is connected to the longitudinal ends of the pair of recess side surfaces 46a, 46a, and faces the opening 46d of the groove-shaped recess 46.

[0174] In Figure 13 ( Figure 14 ) In the ultrasonic horn 42 shown, the corner 46c where the recess side surface 46a intersects the vibration application surface 42t is sharp, and in a cross-sectional view along the MD, the bottom surface 46b of the recess forms an arc-shaped depression in a direction away from the opening 46d.

[0175] In Figure 13 ( Figure 14 ) In the manner shown, the angle formed by the recess side surface 46a and the vibration application surface 42t is 90 degrees. That is, the angle formed by the corner 46c is 90 degrees.

[0176] The manufacturing method of the front sheet 10 using the manufacturing apparatus 100 configured as described above includes a shaping step of deforming the first sheet 1 into a concavo-convex shape following the circumferential surface while rotating the concavo-convex roller 31 (first roller) having concavo-convexities on the circumferential surface.

[0177] In addition, the manufacturing method of the front sheet 10 using the manufacturing apparatus 100 includes an overlapping step of holding the first sheet 1 deformed into a concavo-convex shape on the concavo-convex roller 31 and conveying it, and overlapping the second sheet 2 on the conveyed first sheet 1.

[0178] In addition, the manufacturing method of the front sheet 10 using the manufacturing apparatus 100 includes an ultrasonic treatment step of applying ultrasonic vibration while sandwiching the two overlapping sheets 1, 2 between the convex portion 35 of the concavo-convex roller 31 and the vibration application surface 42t at the front end of the ultrasonic horn 42 provided in the ultrasonic welder 41.

[0179] In the above shaping step, the first sheet 1 is introduced into the meshing portion 33 of the concavo-convexities of the two concavo-convex rollers 31, 32, and the first sheet 1 is deformed into a concavo-convex shape.

[0180] From the viewpoint of making it easier to form the valve film body 20 and the through hole 6, the angle θ35 of the corner at the front end of the convex portion 35 in a cross-sectional view (cross-sectional view along the MD) along the direction orthogonal to the rotation axis of the concavo-convex roller 31 (first roller) (refer to Figure 13 ) is preferably 90 degrees or more, more preferably 105 degrees or more, and also preferably less than 135 degrees, more preferably less than 120 degrees.

[0181] In the above ultrasonic treatment step, as the ultrasonic horn, the above-described specific ultrasonic horn is used, that is, the ultrasonic horn 42 in which a groove-shaped recess 46 extending along the rotation axis (CD) of the uneven roller 31 (first roller) is formed on the vibration application surface 42t, and ultrasonic vibration is applied. As a result, a through-hole 6 is formed in the laminate (welding object) of the first sheet 1 and the second sheet 2 that are overlapped, and a welded portion where the first sheet 1 and the second sheet 2 are welded is formed, and a valve film body 20 is formed in the through-hole 6.

[0182] In the above ultrasonic treatment step, as Figure 13 shown, the welding object (the laminate of the first sheet 1 and the second sheet 2) is conveyed in the MD direction, and is sandwiched between the front end surface 35c of the convex portion 35 of the uneven roller 31 and the vibration application surface 42t of the ultrasonic horn 42 in which the groove-shaped recess 46 is formed, and ultrasonic vibration is applied.

[0183] Here, on the vibration application surface 42t that presses the welding object toward the convex portion 35 side, as Figure 14 shown, there are a pair of corner portions 46c, 46c sandwiching the opening 46d of the groove-shaped recess 46 and located before and after in the MD direction. Therefore, the stress generated when pressing the welding object is concentrated on the corner portion 46c, and the shearing force applied to the welding object via the corner portion 46c is higher than when the corner portion 46c (groove-shaped recess 46) is not formed. Therefore, in the above ultrasonic treatment step, not only the heat generation of the welding object caused by applying ultrasonic vibration but also the strong shearing force caused by the groove-shaped recess 46 act on the welding object. As a result, a welded portion, a through-hole 6, and a valve film body 20 can be formed simultaneously in the portion of the welding object sandwiched between the front end surface 35c of the convex portion 35 and the vibration application surface 42t of the ultrasonic horn 42.

[0184] According to the above ultrasonic treatment step, even if the resin of the first sheet 1 and / or the second sheet 2 is a high melting point resin (for example, PET) with a melting point exceeding 200 °C, the formation of the welded portion, the through-hole 6, and the valve film body 20 can be performed simultaneously.

[0185] In the above ultrasonic treatment step, it is considered that by using an ultrasonic horn in which a groove-shaped recess extending along the rotation axis of the uneven roller is formed on the vibration application surface (refer to Figures 13 to 15),it is easy to form a valve film body 20 at a part of the opening end of the through hole 6. Regarding the formation method of this valve film body 20, the research content of the present inventor will be described below. In the above ultrasonic treatment process, the object to be welded (the laminate of the first sheet 1 and the second sheet 2) is conveyed in the MD direction and clamped between the front end face 35c of the convex portion 35 of the uneven roller 31 and the vibration application surface 42t of the ultrasonic horn 42 having a groove-shaped recess 46 to apply ultrasonic vibration. Thus, a molten portion where the first sheet 1 and the second sheet 2 are melted is formed. On the other hand, the stress generated when pressing the object to be welded is concentrated on the corner portion 46c located on the front side (downstream side) in the MD direction among the pair of corner portions 46c, 46c sandwiching the opening portion 46d of the groove-shaped recess 46 in the front and rear in the MD direction. Therefore, a shearing force acts on the object to be welded, especially the molten portion, via this corner portion 46c. Due to this shearing force, the contact portions of the front side and the rear side in the MD direction of the object to be welded with the corner portions 46c, 46c are broken to form the through hole 6, and since the above-mentioned molten portion extends thinly along the MD direction, a valve film body 20 is formed at a part of the opening end of this through hole 6. That is, by using the shearing force along the MD direction, in the opening end of the through hole 6, the valve film body 20 is formed on at least one or both of the front side (downstream side) and the rear side (upstream side) in the flow direction (MD) during the manufacture of the front sheet 10.

[0186] From the viewpoint of more easily forming the valve film body 20, in the above ultrasonic treatment process, the pressing force applied between the front end face 35c of the convex portion 35 of the uneven roller 31 (the first roller) and the vibration application surface 42t of the ultrasonic horn 42 to the first and second sheets 1, 2 is preferably 10 N / mm or more, more preferably 15 N / mm or more.

[0187] In addition, the above pressing force is preferably 30 N / mm or less, more preferably 25 N / mm.

[0188] The "pressing force" mentioned here is the so-called line pressure, which is represented by the value obtained by dividing the pressing force (N) of the ultrasonic horn 42 by the total length of the tooth widths of the convex portions 35 in contact with the ultrasonic horn 42 (the length along the CD direction of the convex portions 35) (excluding the recesses of the uneven roller 31) (the pressing force per unit length).

[0189] From the same viewpoint as above, the frequency of the applied ultrasonic vibration is preferably 15 kHz or more, more preferably 20 kHz or more.

[0190] In addition, the above frequency is preferably 50 kHz or less, more preferably 40 kHz or less.

[0191] In addition, from the same viewpoint, the amplitude of the applied ultrasonic vibration is preferably 20 μm or more, more preferably 25 μm or more.

[0192] In addition, the above amplitude is preferably 50 μm or less, more preferably 40 μm or less.

[0193] When measuring the frequency and amplitude of the ultrasonic vibration, the displacement of the tip of the ultrasonic horn is measured using a laser displacement meter or the like, and the frequency and amplitude are measured at a sampling rate of 200 kHz or more and a precision of 1 μm or more.

[0194] From the same viewpoint as above, the conveyance speed of the object to be welded (the laminate of the first sheet 1 and the second sheet 2) in the above ultrasonic treatment step is preferably 50 m / min or more, more preferably 100 m / min or more, and preferably 400 m / min or less, more preferably 300 m / min or less.

[0195] According to the ultrasonic horn 42 of the present embodiment, as Figure 14 shown, since the corner 46c of the opening 46d defining the groove-like recess 46 is sharp, the shearing force applied to the object to be welded (the laminate of the first sheet 1 and the second sheet 2) in the above ultrasonic treatment step is higher than that in the case of a rounded corner where the corner 46c is not sharp. Therefore, the simultaneous formation of the welded portion, the through hole 6, and the valve film body 20 can be performed more reliably.

[0196] From the viewpoint of more reliably exerting the effect produced by the corner 46c, the angle formed by the concave side 46a and the vibration application surface 42t in the corner 46c is preferably 45 degrees or more, more preferably 60 degrees or more.

[0197] In addition, the above angle is preferably 135 degrees or less, more preferably 120 degrees or less.

[0198] On the other hand, if a groove-like recess 46 is formed in the vibration application surface 42t of the ultrasonic horn 42, the durability of the ultrasonic horn 42 (especially the main body 420) is reduced, and there is a concern that cracks (fissures) enter the main body 420 or the like starting from the groove-like recess 46 during ultrasonic vibration. In this regard, in the ultrasonic horn 42, by forming the concave bottom surface 46b defining the groove-like recess 46 into an arc shape that is recessed in the direction away from the opening 46d in the cross-sectional view along the MD of the ultrasonic horn 42 as Figure 14 shown, such a concern can be eliminated.

[0199] From the viewpoint of more reliably exerting the effect produced by such a concave bottom surface 46b, the curvature of the concave bottom surface 46b is preferably 1 or more, more preferably 2 or more.

[0200] In addition, the curvature of the concave bottom surface 46b is preferably 10 or less, more preferably 5 or less.

[0201] From the viewpoint of more reliably exerting the effects generated by the above-described groove-shaped recess 46, the dimensions of the groove-shaped recess 46 and the like are preferably set as follows.

[0202] The width W of the groove-shaped recess 46 (refer to Figure 14 and Figure 15 ) is preferably 0.2 mm or more, and more preferably 0.5 mm or more.

[0203] In addition, the width W is preferably 2 mm or less, and more preferably 1 mm or less.

[0204] The width W0 of the vibration application surface 42t (refer to Figure 15 ) is preferably 5 mm or more, and more preferably 10 mm or more.

[0205] In addition, the width W0 is preferably 20 mm or less, and more preferably 15 mm or less.

[0206] When the ratio of the length L of the groove-shaped recess 46 along CD, that is, the length along the rotation axis of the uneven roller 31 (first roller) (refer to Figure 15 ), to the length L0 of the vibration application surface 42t along this direction (refer to Figure 15 ) is expressed as length L / length L0, it is preferably 0.2 or more, and more preferably 0.3 or more.

[0207] In addition, the above ratio (length L / length L0) is preferably 1 or less.

[0208] In the Figure 15 shown manner, the groove-shaped recess 46 extends over the entire length of CD of the vibration application surface 42t, the length L is the same as the length L0, and the above ratio is 1.

[0209] The length L0 of the vibration application surface 42t along CD is preferably 30 mm or more, and more preferably 50 mm or more.

[0210] In addition, the length L0 is preferably 200 mm or less, and more preferably 150 mm or less.

[0211] The depth D of the groove-shaped recess 46 (refer to Figure 14 . The length from the vibration application surface 42t to the portion of the recess bottom surface 46b that is farthest from the vibration application surface 42t.) is preferably 0.3 mm or more, and more preferably 0.5 mm or more.

[0212] In addition, the depth D is preferably 5 mm or less, and more preferably 2 mm or less.

[0213] The groove-shaped recess 46 is preferably formed at the center of the MD of the vibration application surface 42t, and more preferably formed within 5 mm, and still more preferably within 3 mm, on the upstream side of the MD starting from the center of the MD of the vibration application surface 42t.

[0214] In Figure 15 the manner shown, the groove-shaped recess 46 is formed at the center of the MD of the vibration application surface 42t.

[0215] As described above, the manufacturing apparatus 100 includes a preheating member 51 (preheating mechanism 50). In the method for manufacturing the front sheet 10 using the manufacturing apparatus 100, since at least one of the first sheet 1 and the second sheet 2 supplied before the ultrasonic treatment step is preheated by the preheating member 51, the simultaneous formation of the welded portion, the through hole 6, and the valve film body 20 can be performed more reliably in combination with the effect brought by the groove-shaped recess 46.

[0216] The conditions for preheating the welding object by the preheating member 51 are not particularly limited and can be appropriately adjusted according to the type of the welding object and the like. However, it is preferable to heat at least one of the first sheet 1 and the second sheet 2 to a temperature lower than the melting point of the sheet and higher than a temperature 50°C lower than the melting point. That is, before the application of ultrasonic vibration, it is preferable to perform any one or both of the following (1) and (2). (1) The first sheet 1 is preheated to a temperature lower than the melting point of the first sheet 1 and higher than a temperature 50°C lower than the melting point. (2) The second sheet 2 is preheated to a temperature lower than the melting point of the second sheet 2 and higher than a temperature 50°C lower than the melting point.

[0217] It is preferable to preheat the first sheet 1 to a temperature lower than the melting point of the first sheet 1 and higher than a temperature 50°C lower than the melting point, and preheat the second sheet 2 to a temperature lower than the melting point of the second sheet 2 and higher than a temperature 50°C lower than the melting point.

[0218] As the method of (1) above, that is, the method of heating the first sheet 1 to a temperature lower than the melting point of the first sheet 1 and higher than a temperature 50°C lower than the melting point, for example, the temperature of the first sheet 1 on the concavo-convex roller 31 (first roller) is measured between the meshing portion 33 of the concavo-convex rollers 31 and 32 and the ultrasonic vibration application portion 36 of the ultrasonic welder 41, and the temperature of the preheating member 51 is controlled so that the measured value is within the above specific range.

[0219] As a method of preheating the first sheet 1 to a temperature within a specific range, instead of the method of controlling the temperature of the peripheral surface of the concavo-convex roller 31 using a heater disposed in the concavo-convex roller 31 to make the first sheet 1 reach a temperature within a specific range, various methods can be used.

[0220] For example, a method can be cited in which a heater, a hot air outlet, and a far-infrared irradiation device are provided near the circumferential surface of the uneven roller 31, and the temperature of the circumferential surface of the uneven roller 31 before or after laminating the first sheet 1 is controlled using them, and a method in which the uneven roller 32 (second roller) that contacts the first sheet 1 at the engaging portion 33 is heated, and the temperature of the first sheet 1 is controlled by controlling the temperature of its circumferential surface.

[0221] In addition, for the first sheet 1 before being laminated on the uneven roller 31, a method can be cited in which a heated roller is brought into contact with it, or it is passed through a space maintained at a high temperature, or hot air is blown.

[0222] As the method of (2) above, that is, a method of heating the second sheet 2 to a temperature lower than the melting point of the second sheet 2 and higher than a temperature 50°C lower than the melting point, it is preferable to measure the temperature of the second sheet 2 before converging with the first sheet 1 using a temperature measuring mechanism arranged in the conveying path of the second sheet 2, and control the temperature of the heating mechanism (not shown) of the second sheet 2 arranged in the conveying path of the second sheet 2 so that the measured value is within the above specific range.

[0223] The heating mechanism of the second sheet 2 can be a contact method such as bringing a heated roller into contact with it, or a non-contact method such as passing it through a space maintained at a high temperature, or blowing or passing hot air, or irradiating infrared rays.

[0224] The melting points of the first sheet 1 and the second sheet 2 can be measured using, for example, a differential scanning calorimeter (DSC) PYRIS Diamond DSC manufactured by Perkin-Elmer. In this measurement method, the melting points of the measurement objects (the first sheet 1, the second sheet 2) are estimated from the peaks of the measurement data.

[0225] When the first sheet 1 or the second sheet 2 is a fiber sheet such as a non-woven fabric, and the constituent fibers are composite fibers composed of multiple components such as core-sheath type and side-by-side type, the melting point of the sheet is taken as the melting point of the lowest temperature among the multiple melting points measured by DSC as the melting point of the composite fiber sheet.

[0226] In addition, as described above, the manufacturing apparatus 100 has a tip heating member 61 (tip heating mechanism 60). In the above ultrasonic treatment process, since the vibration application surface 42t heated by the tip heating member 61 is brought into contact with the welding object (the laminate of the first sheet 1 and the second sheet 2), the formation of the welded portion, the through hole 6, and the valve film body 20 can be performed more reliably in cooperation with the effect brought about by the groove-like recess 46.

[0227] The conditions for heating by the tip heating member 61 are not particularly limited and can be appropriately adjusted according to the type of the welding object, etc.

[0228] For example, instead of the preheating member 51, the method of (2) above can be implemented by using the sonotrode heating member 61. That is, by controlling the temperature of the ultrasonic sonotrode 42 (vibration application surface 42t) heated by the sonotrode heating member 61, the temperature of the second sheet 2 to which ultrasonic vibration is about to be applied can be preheated to a temperature less than the melting point of the second sheet 2 and more than 50 °C lower than the melting point. In this state, ultrasonic vibration is applied to the first and second sheets 1 and 2 sandwiched between the convex portion 35 of the uneven roller 31 and the vibration application surface 42t.

[0229] In addition, either the preheating member 51 or the sonotrode heating member 61 can be used alone, or both can be used together.

[0230] From the viewpoint of more easily forming the through hole 6 and the valve film body 20, in the manufacturing method of the front sheet 10, the first sheet 1 and the second sheet 2 are preferably spunbond nonwoven fabrics and thermally bonded nonwoven fabrics containing core-sheath type composite fibers as constituent fibers. As the above-mentioned core-sheath type composite fiber, a core-sheath type composite fiber having polyethylene terephthalate (PET) as the core part and polyethylene (PE) as the sheath part is preferably used.

[0231] Figures 16 to 19 The main part (front end part) of another embodiment of the ultrasonic sonotrode of the present invention is shown.

[0232] Regarding the embodiments described later, the description will be mainly focused on the components different from the above ultrasonic sonotrode 42. The same components are denoted by the same reference numerals and the description thereof is omitted. For the components not specifically described, the description of the ultrasonic sonotrode 42 is appropriately applied.

[0233] In Figure 16 In the ultrasonic sonotrode 42A shown, in the cross-sectional view of the ultrasonic sonotrode 42 along the MD as shown in this figure, the bottom surface 46b of the groove-shaped recess 46 is a straight line, and the groove-shaped recess 46 is formed in a rectangular shape in this cross-sectional view. That is, the bottom surface 46b of the ultrasonic sonotrode 42A is flat.

[0234] When using the ultrasonic sonotrode 42A, it basically has the same effect as when using the above ultrasonic sonotrode 42. However, from the viewpoint of more reliably suppressing the reduction of the durability of the above ultrasonic sonotrode 42 and the resulting cracks and other defective conditions due to the formation of the groove-shaped recess 46, the shape of the bottom surface 46b in the above cross-sectional view is preferably an arc shape recessed in the direction away from the opening portion 46d, as Figure 14 shown.

[0235] In Figure 17In the ultrasonic horn 42B shown, the vibration applying surface 42t forms an arc shape that is concave in a direction away from the rotation axis when viewed in a cross section along a direction (MD) orthogonal to the rotation axis of the concave-convex roller 31 (first roller).

[0236] The vibration applying surface 42t mentioned here is assumed to be a case where there is no groove-shaped recessed portion 46. More specifically, in the case Figure 17 In the cross-sectional view along MD shown, the vibration applying surface 42t is a surface that is virtually extended from the corner 46c on one side of MD to the corner 46c on the other side, sandwiching the opening 46d of the groove-shaped recessed portion 46.

[0237] Since the cross-sectional shape of the vibration applying surface 42t along MD is arc-shaped, the shear force applied to the welding object (the stack of the first sheet 1 and the second sheet 2) in the above-mentioned ultrasonic treatment process is increased, and thus, in conjunction with the effect produced by the groove-shaped recessed portion 46, the welding portion, the through hole 6 and the valve membrane body 20 can be further reliably formed simultaneously.

[0238] In such Figure 17 In the cross-sectional view along MD shown in FIG. 1 , the arc-shaped vibration applying surface 42t is preferably curved along a circular track (not shown) through which the front end of the convex portion 35 of the concave-convex roller 31 (first roller) passes. As a result, the time for the welding object (the laminate of the first sheet 1 and the second sheet 2) to be sandwiched between the front end surface 35c of the convex portion 35 and the vibration applying surface 42t becomes longer, and the welding portion, the through hole 6, and the valve film body 20 can be formed simultaneously more reliably.

[0239] In addition, when the vibration applying surface 42t of the ultrasonic horn 42 forms an arc shape in the cross-sectional view along MD, it is preferred that the front end surface 35c of each of the multiple convex portions 35 of the corresponding concave-convex roller 31 forms a convex shape in the direction away from the rotation axis of the concave-convex roller 31 in the cross-sectional view, and the bending direction is consistent with the vibration applying surface 42t.

[0240] The curvature radius of the vibration applying surface 42 t of the ultrasonic horn 42B is preferably 100% or more with respect to the curvature radius of the front end surface 35 c of the convex portion 35 of the concave-convex roller 31 .

[0241] Furthermore, the curvature radius of the vibration applying surface 42t is preferably 500% or less, and more preferably 200% or less.

[0242] In addition, Figure 17 In the ultrasonic horn 42B shown, the vibration applying surface 42t is formed into an arc shape along the cross-sectional shape of MD in the entire area in the direction parallel to the rotation axis of the concave-convex roller 31, but parts with different cross-sectional shapes can also be provided in the direction parallel to the rotation axis, such as the part that is not opposite to the convex part 35.

[0243] For example Figure 11 As shown, when there is a gap G between adjacent gears constituting the uneven roller 31, a flat portion or the like that does not protrude from the arc-shaped vibration application surface 42t may be provided at a portion of the vibration application surface 42t corresponding to the gap G.

[0244] Figure 18 In the ultrasonic horn 42C shown, the front end portion of the ultrasonic horn 42 includes a heat storage portion 421 fixed to the metal main body portion 420 of the ultrasonic horn 42C, and the vibration application surface 42t is formed by the heat storage portion 421.

[0245] The groove-shaped recess 46 is formed at least in the heat storage portion 421.

[0246] In Figure 18 , the groove-shaped recess 46 is only formed in the heat storage portion 421, but it may also penetrate the heat storage portion 421 in the thickness direction and extend to the main body portion 420.

[0247] In addition, Figure 18 The vibration application surface 42t formed by the heat storage portion 421, similar to the vibration application surface 42t of the above-described ultrasonic horn 42B, is formed in an arc shape in a cross-sectional view along the MD, but it may also be flat instead of forming an arc shape.

[0248] The heat storage portion 421 is formed of a heat storage material that is a material having a lower thermal conductivity than the metal constituting the main body portion 420.

[0249] The thermal conductivity of the heat storage material constituting the heat storage portion 421 is preferably 2.0 W / mK or less, more preferably 1.0 W / mK or less, from the viewpoint of preventing heat dissipation to the ultrasonic horn and the atmosphere.

[0250] In addition, the thermal conductivity of the above heat storage material is preferably 0.1 W / mK or more, more preferably 0.5 W / mK or more, from the viewpoint of effectively heating the sheet.

[0251] The thermal conductivity of the heat storage material can be measured by a thermal conductivity measuring device according to a usual method.

[0252] When the vibration application surface 42t is formed by the heat storage portion 421, the heat of the first and second sheets 1 and 2 that generate heat by ultrasonic vibration is accumulated in the heat storage portion 421. As a result, the temperature of the heat storage portion 421 rises and the first sheet 1 and the second sheet 2 can be heated. Therefore, in cooperation with the action effect generated by the groove-shaped recess 46 formed in the vibration application surface 42t, the simultaneous formation of the welded portion, the through hole 6, and the valve film body 20 can be performed more reliably.

[0253] In addition, when the vibration application surface 42t is formed by the heat storage part 421, it has the advantages of suppressing the occurrence of defective conditions such as the adhesion of the molten resin generated due to the melting of the first and second sheets 1 and 2 to the conveying mechanism and the winding of the sheets around the conveying rollers, and reducing the maintenance burden of the manufacturing apparatus.

[0254] The thickness Th of the heat storage part 421 (refer to Figure 18 ) is not particularly limited. From the viewpoint of more reliably exerting the effect brought by the heat storage part 421, it is preferably 5 μm or more, more preferably 10 μm or more.

[0255] In addition, the thickness Th is preferably 100 μm or less, more preferably 50 μm or less.

[0256] As the heat storage material constituting the heat storage part 421, on the premise that the thermal conductivity is lower than that of the metal constituting the main body part 420, a synthetic resin excellent in abrasion resistance and heat resistance is preferably used. As such a synthetic resin, for example, polyimide, polybenzimidazole, polyether ethyl ketone, polyphenylene sulfide, polyetherimide, polyamideimide, etc., with a Rockwell hardness of R120 or more and R140 or less and a heat resistance temperature of 150 °C or more and 500 °C or less can be cited.

[0257] As the above heat storage material, polyimide, polybenzimidazole, etc., with a Rockwell hardness of R125 or more and R140 or less and a heat resistance temperature of 280 °C or more and 400 °C or less are particularly preferred.

[0258] 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.

[0259] The means for fixing the synthetic resin heat storage part 421 to the metal main body part 420 is not particularly limited, and a known fixing mechanism can be adopted.

[0260] The synthetic resin heat storage part 421 is formed, for example, by thermal spraying on the metal main body part 420 and can be fixed to the main body part 420.

[0261] The "thermal spraying" mentioned here refers to a known surface treatment method in which particles of a thermal spraying material such as metal or ceramic in a molten state or in a state close to melting due to heating are accelerated to collide with the substrate surface at a high speed to form a coating film on the substrate surface.

[0262] As a thermal spraying material, a material that can be thermally sprayed and contribute to the improvement of the fixing strength of the heat storage part 421 made of synthetic resin can be used without particular limitation. From the viewpoints of excellent bonding force to the main body part 420 formed of a metal such as a titanium alloy, excellent abrasion resistance and heat resistance, it is preferable to use ceramics such as tungsten carbide, zirconia, chromium carbide, alloys such as aluminum-magnesium alloy, zinc-aluminum alloy, metals such as aluminum, stainless steel, titanium, molybdenum, cermet which is a composite of metal and ceramic, etc.

[0263] Figure 19 In the ultrasonic welding head 42D shown, uneven portions 48 are formed in a groove-shaped recess non-forming portion 47 in the vibration application surface 42t.

[0264] More specifically, as shown in (a) of Figure 19 , a part of the groove-shaped recess non-forming portion 47 is the uneven portion 48, and the remaining part of the groove-shaped recess non-forming portion 47 is a smooth portion 49 without unevenness. The uneven portion 48 has a larger surface roughness than the smooth portion 49, and thus has a stronger frictional force.

[0265] In the above ultrasonic treatment process, a shearing force acts on the portion pressed by the uneven portion 48 in the object to be welded (the laminate of the first sheet 1 and the second sheet 2). Therefore, in addition to the effect generated by the groove-shaped recess 46, the simultaneous formation of the welded portion, the through hole 6, and the valve film body 20 can be performed more reliably.

[0266] The uneven portion 48 is as shown in (b) of Figure 19 , and has a plurality of convex portions 481 and a plurality of concave portions 482. The convex portion 481 is formed in a triangular shape in the cross-sectional view along the MD as shown in this figure, but the shape of the convex portion 481 in this cross-sectional view is not particularly limited, and for example, it may also be a quadrilateral, a trapezoid, etc.

[0267] In addition, as an example of the arrangement pattern of the plurality of convex portions 481 in the uneven portion 48, an arrangement pattern in which the convex portions 481 are arranged at equal intervals in the CD (the direction along the rotation axis of the uneven roller 31) and the convex portions arranged at equal intervals in the MD.

[0268] As another example of the above arrangement pattern, an arrangement pattern in which the convex portions 481 are arranged at equal intervals in the CD and the convex portions arranged at equal intervals in the MD, and the adjacent convex portions in the MD are offset by half a pitch from each other can be cited.

[0269] The uneven portion 48 can be formed by performing knurling or thermal spraying treatment on the groove-shaped recess non-forming portion 47 in the vibration application surface 42t.

[0270] In Figure 19In the shown manner, there is a smooth portion 49 between the groove-shaped recess 46 and the uneven portion 48. However, there may also be no smooth portion 49 between the groove-shaped recess 46 and the uneven portion 48, and the groove-shaped recess 46 and the uneven portion 48 are adjacent to each other in the MD direction.

[0271] In addition, there may be no smooth portion 49 on the vibration application surface 42t, and the entire non-formation portion 47 of the groove-shaped recess is the uneven portion 48.

[0272] From the viewpoint of more reliably exerting the effect produced by the uneven portion 48, regarding the surface roughness of the uneven portion 48, the arithmetic mean roughness Ra is preferably 3.2 μm or more, and more preferably 6.3 μm or more.

[0273] In addition, regarding the surface roughness of the uneven portion 48, the arithmetic mean roughness Ra is preferably 12.5 μm or less, and more preferably 25 μm or less.

[0274] The arithmetic mean roughness Ra can be measured by various surface roughness measuring instruments. For example, it can be measured using a surface roughness measuring instrument manufactured by Mitutoyo Corporation.

[0275] From the same viewpoint, it is preferable to set the size of the uneven portion 48 and the like in the following manner.

[0276] The ratio of the area (48S) of the uneven portion 48 to the area (47S) of the non-formation portion 47 of the groove-shaped recess on the vibration application surface 42t, that is, the ratio calculated according to (48S / 47S)×100 is preferably 15% or more, and more preferably 30% or more.

[0277] In addition, the above ratio is preferably 100% or less, and more preferably 80% or less.

[0278] The number per unit area (1 cm 2 ) of the convex portions 481 constituting the uneven portion 48 is preferably 1 or more, and more preferably 100 or more.

[0279] In addition, the number per unit area (1 cm 2 ) of the convex portions 481 is preferably 1,000,000 or less, and more preferably 10,000 or less.

[0280] When looking down at the uneven portion 48, the area of one convex portion 481 is preferably 0.0001 mm 2 or more, and more preferably 0.01 mm 2 or more.

[0281] In addition, the area of one convex portion 481 is preferably 100 mm 2 or less, and more preferably 1 mm 2 or less.

[0282] As described above, the present invention has been described based on its preferred embodiments. The present invention is not limited by any of the above embodiments and can be appropriately modified without departing from the gist of the present invention.

[0283] For example, the front sheet 10 of the above embodiment has a laminated structure formed by laminating the first sheet 1 and the second sheet 2, but the front sheet 10 may also be a single-layer structure. From the viewpoint of further improving the strength of the convex portion 5 and further improving the resistance to body pressure of the wearer, the front sheet 10 preferably has the above laminated structure.

[0284] In addition, one groove-shaped recess 46 is formed in the vibration application surface 42t, but a plurality of them may be formed. In this case, for example, a plurality of groove-shaped recesses 46 extending on the CD may be arranged at intervals on the MD, or a plurality of groove-shaped recesses 46 extending on the CD may be arranged at intervals on the CD.

[0285] In addition, the structure of the above one embodiment can also be applied to other embodiments.

[0286] For example, the vibration application surface 42t of the ultrasonic welding head 42D having the uneven portion 48 (refer to Figure 19 ), as Figure 17 shown, may also be formed in an arc shape recessed in a direction away from the rotation axis in a cross-sectional view along a direction orthogonal to the rotation axis of the uneven roller 31 (a cross-sectional view along the MD).

[0287] In addition, as Figure 18 shown, when the vibration application surface 42t is formed by the heat storage portion 421, the uneven portion 48 may also be formed in the vibration application surface 42t formed by the heat storage portion 421.

[0288] Regarding the above embodiments of the present invention, the following front sheet for absorbent articles and absorbent articles having the same are further disclosed.

[0289] <1>

[0290] A front sheet for absorbent articles, which is formed of a fiber material, has a plurality of through holes, and a valve film body formed by membrane-forming the fiber material is formed at a part of the open end of the through holes,

[0291] The valve film body can rotate about a part of the open end of the through hole.

[0292] <2>The front sheet for absorbent articles according to <1> above, wherein,

[0293] When a load is locally applied to the valve film body from the side opposite to the skin-facing side, the entire valve film body can rotate about a part of the open end of the through-hole.

[0294] <3>

[0295] The front sheet for absorbent articles described in <1> or <2> above, wherein

[0296] The area of the valve film body is 5% or more and 50% or less, preferably 10% or more and 40% or less, relative to the area of the through-hole.

[0297] <4>

[0298] The front sheet for absorbent articles described in any one of <1> to <3> above, wherein

[0299] The area of the through-hole is 1 mm 2 or more and 10 mm 2 or less, preferably 2 mm 2 or more and 8 mm 2 or less.

[0300] <5>

[0301] The front sheet for absorbent articles described in any one of <1> to <4> above, wherein

[0302] The area of the valve film body is 0.5 mm 2 or more and 5 mm 2 or less, preferably 1 mm 2 or more and 2.5 mm 2 or less.

[0303] <6>

[0304] The front sheet for absorbent articles described in any one of <1> to <5> above, wherein

[0305] In a portion adjacent to the through-hole, there is a convex portion protruding toward one surface side of the front sheet for absorbent articles,

[0306] The valve film body extends from the bottom of the convex portion toward the inside of the through-hole.

[0307] <7>

[0308] The front sheet for absorbent articles described in <6> above, wherein

[0309] It has a laminated structure formed by laminating a first sheet and a second sheet, and at least a part of the portion other than the through-hole in the first sheet forms the convex portion protruding toward the opposite side of the second sheet.

[0310] <8>

[0311] The front sheet for absorbent articles according to any one of <1> to <7> above, wherein,

[0312] The valve film body has: a base end edge portion located at a part of the opening end; a free end edge portion located on the opposite side of the base end edge portion; and a pair of side edge portions located between the base end edge portion and the free end edge portion,

[0313] Neither of the pair of side edge portions is connected to the opening end.

[0314] <9>

[0315] The front sheet for absorbent articles according to <8> above, wherein,

[0316] The percentage of the maximum length in the extending direction of the valve film body with respect to the length of the base end edge portion is 10% or more and 50% or less, preferably 20% or more and 40% or less.

[0317] <10>

[0318] The front sheet for absorbent articles according to <8> or <9> above, wherein,

[0319] The maximum length in the extending direction of the valve film body is 1 mm or more and 5 mm or less, preferably 2 mm or more and 4 mm or less.

[0320] <11>

[0321] The front sheet for absorbent articles according to any one of <8> to <10> above, wherein,

[0322] The length of the base end edge portion is 1 mm or more and 10 mm or less, preferably 2 mm or more and 5 mm or less.

[0323] <12>

[0324] The front sheet for absorbent articles according to <8> above, wherein,

[0325] In a plan view, the free end edge portion has a wave shape.

[0326] <13>

[0327] The front sheet for absorbent articles according to <12> above, wherein,

[0328] The ratio of the undulating length of the free end edge portion to the length of the base end edge portion is greater than 1 and less than 10, preferably 2 or more and 5 or less.

[0329] <14>

[0330] The topsheet for an absorbent article according to any one of <1> to <13> above, wherein,

[0331] The minimum thickness of the valve film body is 10 μm or more and 1 mm or less, preferably 20 μm or more and 500 μm or less.

[0332] <15>

[0333] The topsheet for an absorbent article according to any one of <1> to <14> above, wherein,

[0334] The valve film body has a thick portion with a greater thickness than other portions on the base end edge portion side of a part located at the opening end.

[0335] <16>

[0336] The topsheet for an absorbent article according to <15> above, wherein,

[0337] The ratio of the minimum thickness of the valve film body to the maximum thickness of the thick portion is 0.5% or more and 10% or less, more preferably 1% or more and 5% or less.

[0338] <17>

[0339] The topsheet for an absorbent article according to <15> or <16> above, wherein,

[0340] The maximum thickness of the thick portion 25 is 20 μm or more and 1.1 mm or less, preferably 200 μm or more and 600 μm or less.

[0341] <18>

[0342] The topsheet for an absorbent article according to any one of <1> to <17> above, wherein,

[0343] Among all the through-holes per unit area (10 mm × 10 mm) in the topsheet for the absorbent article, the proportion of the number of through-holes per unit area having the valve film body formed therein is 30% or more, preferably 50% or more, and more preferably the valve film body is formed in all the through-holes.

[0344] <19>

[0345] The topsheet for an absorbent article according to any one of <1> to <18> above, wherein,

[0346] The number of through-holes having the valve film body formed therein per unit area (10 mm × 10 mm) is 1 or more and 20 or less, preferably 4 or more and 15 or less.

[0347] <20>

[0348] An absorbent article having the front sheet for absorbent articles according to any one of <1> to <19> above, wherein in the absorbent article,

[0349] it includes a fibrous sheet having a plurality of concave portions and convex portions disposed on the non-skin-facing side of the front sheet for absorbent articles,

[0350] the through holes and the valve film body of the front sheet for absorbent articles at least partially overlap with the concave portions in the fibrous sheet.

[0351] <21>

[0352] The absorbent article described in <20> above, wherein,

[0353] the depth of the concave portions of the fibrous sheet is 0.5 mm or more and 5 mm or less, preferably 1 mm or more and 3 mm or less.

[0354] Industrial availability

[0355] The front sheet for absorbent articles according to the present invention and the absorbent article having the same can maintain the permeability of excrement and can suppress its contact with the skin.

Claims

1. A front sheet for an absorbent article, characterized in that: It is formed of a fibrous material, has a plurality of through-holes, and a valve film body formed by membrane formation of the fibrous material is formed at a part of the opening end of the through-hole. The valve film body is not formed continuously around the entire circumference of the opening end of the through-hole. The valve film body can rotate in the thickness direction of the front sheet for the absorbent article with a part of the opening end of the through-hole as an axis. The valve film body has: a base end edge portion located at a part of the opening end; a free end edge portion located on the opposite side of the base end edge portion; and a pair of side edge portions located between the base end edge portion and the free end edge portion. Neither of the pair of side edge portions is connected to the opening end.

2. The front sheet for an absorbent article according to claim 1, characterized in that: When a load is locally applied to the valve film body from the skin-facing side, the entire valve film body can rotate with a part of the opening end of the through-hole as an axis.

3. The front sheet for an absorbent article according to claim 1 or 2, characterized in that: The area of the valve film body is 5% or more and 50% or less with respect to the area of the through-hole.

4. The front sheet for an absorbent article according to claim 1 or 2, characterized in that: The area of the through hole is 1 mm 2 or more and 10 mm 2 or less.

5. The front sheet for an absorbent article according to claim 1 or 2, characterized in that: The area of the valve diaphragm body is 0.5 mm 2 or more and 5 mm 2 or less.

6. The front sheet for an absorbent article according to claim 1 or 2, characterized in that: At a portion adjacent to the through-hole, there is a convex portion protruding toward one surface side of the front sheet for the absorbent article. The valve film body extends from the bottom of the convex portion toward the inside of the through-hole.

7. The front sheet for an absorbent article according to claim 6, characterized in that: It has a laminated structure formed by laminating a first sheet and a second sheet, and the convex portion protruding toward the opposite side of the second sheet is formed at least in part of the portion other than the through-hole in the first sheet.

8. The front sheet for an absorbent article according to claim 1 or 2, characterized in that: The percentage of the maximum length in the extending direction of the valve film body with respect to the length of the base end edge portion is 10% or more and 50% or less.

9. The front sheet for an absorbent article according to claim 1 or 2, characterized in that: The maximum length in the extending direction of the valve film body is 1 mm or more and 5 mm or less.

10. The front sheet for an absorbent article according to claim 1 or 2, characterized in that: The length of the base end edge portion is 1 mm or more and 10 mm or less.

11. The front sheet for an absorbent article according to claim 1 or 2, characterized in that: The free end edge portion has a wavy shape in a plan view.

12. The front sheet for an absorbent article according to claim 11, characterized in that: The ratio of the zigzag length of the free end edge portion to the length of the base end edge portion is greater than 1 and less than 10.

13. The front sheet for an absorbent article according to claim 1 or 2, characterized in that: The minimum thickness of the valve film body is 10 μm or more and 1 mm or less.

14. The front sheet for an absorbent article according to claim 1 or 2, characterized in that: The valve film body has a large thickness portion with a greater thickness than other portions on the base end edge portion side of a part located at the opening end.

15. The front sheet for an absorbent article according to claim 14, wherein: The ratio of the minimum thickness of the valve film body to the maximum thickness of the large thickness portion is 0.5% or more and 10% or less.

16. The front sheet for an absorbent article according to claim 14, wherein: The maximum thickness of the large thickness portion is 20 μm or more and 1.1 mm or less.

17. The front sheet for an absorbent article according to claim 1 or 2, wherein: Among all the through holes per unit area (10 mm × 10 mm) in the front sheet for an absorbent article, the proportion of the number of through holes per unit area having the valve film body formed therein is 30% or more.

18. The front sheet for an absorbent article according to claim 1 or 2, wherein: The number of through holes having the valve film body formed therein per unit area (10 mm × 10 mm) is 1 or more and 20 or less.

19. An absorbent article having the front sheet for an absorbent article according to any one of claims 1 to 18, wherein the absorbent article: Comprises a fibrous sheet having a plurality of concave portions and convex portions disposed on the non-skin facing side of the front sheet for an absorbent article, The through holes and the valve film body of the front sheet for an absorbent article overlap at least partially with the concave portions in the fibrous sheet.

20. The absorbent article according to claim 19, wherein: The depth of the concave portions of the fibrous sheet is 0.5 mm or more and 5 mm or less.

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