Top sheet for absorbent article and absorbent article including same

Abstract

To provide a surface sheet for an absorbent article capable of suppressing a contact with the skin while keeping permeability of bodily wastes, and an absorbent article with the surface sheet.SOLUTION: A surface sheet 10 for an absorbent article according to the present invention comprises a fiber material, has a plurality of through holes 6, and at a part of the opening edges of the through holes 6, is provided with valve film bodies 20 obtained by making the fiber material into a film. The valve film bodies 20 are capable of rotating about the part of the opening edges of the through holes 6. The surface sheet 10 has, at positions adjacent to the through holes 6, protrusions 5 that protrude toward one surface side of the surface sheet 10. The valve film bodies 20 preferably extend from the bottoms of the protrusions 5 toward the inside of the through holes 6.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a topsheet for an absorbent article and an absorbent article including the same. [Background technology]

[0002] Absorbent articles such as disposable diapers generally include a topsheet that is in contact with the wearer's skin on the skin-facing side of a liquid-retaining absorbent body. The applicant previously disclosed a sheet that includes a first nonwoven fabric and a second nonwoven fabric as the topsheet, and that has through-holes formed in the fused portions where the two nonwoven fabrics are partially heat-fused and joined (Patent Documents 1 and 2). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2015-142721 [Patent Document 2] Japanese Patent Application Publication No. 2018-088997 Summary of the Invention [Problem to be solved by the invention]

[0004] Providing multiple through holes in the topsheet is effective in increasing the permeability of urine, loose stool, etc. However, even if excrement such as urine or loose stool migrates to the non-skin-facing side of the topsheet through the through holes, the excrement remaining directly below the through holes or the excrement returning to the skin-facing side of the topsheet through the through holes may come into contact with the skin of the wearer of the absorbent article, causing skin contamination. On the other hand, if the through holes are made smaller to solve this problem, there is a risk that the permeability of excrement will be impaired. The topsheets described in Patent Documents 1 and 2 have room for improvement in terms of preventing excrement from contacting the skin while maintaining permeability.

[0005] Therefore, the present invention relates to providing a topsheet for absorbent articles that can suppress contact with the skin while maintaining permeability of excrement, and an absorbent article equipped with the topsheet. [Means for solving the problem]

[0006] The present invention relates to a topsheet for absorbent articles, which is made of a fibrous material and has a plurality of through-holes. the topsheet for absorbent articles is provided with a valve membrane body formed of a film of a fibrous material at a part of an open end of the through-hole, It is preferable that the valve membrane is rotatable about a part of the open end of the through hole.

[0007] The present invention also relates to an absorbent article provided with the topsheet for an absorbent article. The absorbent article preferably includes a fiber sheet having a plurality of recesses and protrusions, the fiber sheet being disposed on the non-skin-facing side of the topsheet for absorbent articles. In the absorbent article, it is preferable that the through-holes and the valve membrane of the topsheet for absorbent articles at least partially overlap with the recesses in the fiber sheet. [Effects of the Invention]

[0008] The topsheet for absorbent articles of the present invention and the absorbent article including the same can prevent contact with the skin while maintaining permeability of excrement. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a diagram showing one embodiment of the topsheet for absorbent articles of the present invention, and is an enlarged plan view of the sheet as viewed from the first sheet side. [Figure 2] FIG. 2 is an end view of the topsheet shown in FIG. 1 taken along the Y direction. [Figure 3] FIG. 3 is an enlarged plan view of the through hole shown in FIG. [Figure 4] FIG. 4 is a perspective view for explaining the function and effect of the valve body shown in FIG. [Figure 5] FIG. 5 is an enlarged end view of the convex portion and valve body shown in FIG. [Figure 6] FIG. 6 is an enlarged plan view of a through hole showing a variation of the through hole according to the present invention. [Figure 7] FIG. 7 is a developed plan view schematically showing the skin-facing side (topsheet side) of an open-type disposable diaper, which is one embodiment of the absorbent article of the present invention, in an open and stretched state. [Figure 8] FIG. 8 is a cross-sectional view schematically showing a cross section taken along line II-II in FIG. [Figure 9] FIG. 9 is an enlarged end view of the topsheet and sublayer shown in FIG. [Figure 10] FIG. 10 is a schematic diagram showing one embodiment of a topsheet manufacturing apparatus. [Figure 11] FIG. 11 is an enlarged perspective view showing a main part of the uneven roll (first roll) shown in FIG. [Figure 12] FIG. 12 is a front view showing the main part of the ultrasonic fusion machine shown in FIG. 10 as viewed from the upstream side in the conveying direction of the second sheet. [Figure 13] FIG. 13 is a diagram showing the main part (the tip of the ultrasonic horn and its vicinity) of the manufacturing apparatus shown in FIG. [Figure 14] FIG. 14 is an enlarged cross-sectional view schematically illustrating a cross section of the tip of the ultrasonic horn shown in FIG. 13 along the direction (MD) perpendicular to the rotation axis of the concave-convex roll. [Figure 15] FIG. 15 is a plan view of the vibration application surface (tip surface) of the ultrasonic horn shown in FIG. [Figure 16] FIG. 16 is a view corresponding to FIG. 14, showing another embodiment of the ultrasonic horn according to the present invention. [Figure 17] FIG. 17 is a view corresponding to FIG. 14 showing still another embodiment of the ultrasonic horn according to the present invention. [Figure 18] FIG. 18 is a view equivalent to FIG. 14 showing still another embodiment of the ultrasonic horn according to the present invention. [Figure 19]Figure 19(a) is a diagram equivalent to Figure 14 showing yet another embodiment of the ultrasonic horn according to the present invention, and Figure 19(b) is an enlarged schematic diagram showing the uneven portion shown in Figure 19(a) and its vicinity. DETAILED DESCRIPTION OF THE INVENTION

[0010] The present invention will be described below based on preferred embodiments with reference to the drawings. In the following description of the drawings, the same or similar parts are designated by the same or similar reference numerals. The drawings are basically schematic, and the ratios of the dimensions may differ from those of the actual parts.

[0011] 1 and 2 show a topsheet for absorbent articles of this embodiment (hereinafter simply referred to as "topsheet 10"). The topsheet 10 of this embodiment is a fiber sheet made of a fiber material and has through-holes 6 penetrating the sheet.

[0012] The topsheet 10 has a laminated structure in which a first sheet 1 and a second sheet 2 made of a fibrous material are laminated together. The first sheet 1 and the second sheet 2 are joined together via a fused portion (not shown). The first sheet 1 and the second sheet 2 are made of fiber sheets made of a fiber material. Examples of fiber sheets that can be used include nonwoven fabric, woven fabric, and knitted fabric. From the standpoint of feel, etc., it is preferable to use nonwoven fabric. The types of fiber sheets that make up the first sheet 1 and the second sheet 2 may be the same or different.

[0013] Examples of nonwoven fabrics include air-through nonwoven fabrics, spunbond nonwoven fabrics, spunlace nonwoven fabrics, meltblown nonwoven fabrics, resin-bonded nonwoven fabrics, needle-punched nonwoven fabrics, etc. A laminate of two or more of these nonwoven fabrics can also be used. The basis weight of each of the first sheet 1 and the second sheet 2 is preferably 10 g / m 2 More preferably, 15 g / m 2 or more, and preferably 40 g / m 2Less than 35 g / m 2 and preferably 10 g / m 2 More than 40g / m 2 Less than 15 g / m, more preferably 2 More than 35g / m 2 The following is the result.

[0014] As the fibers constituting the nonwoven fabric, fibers made of various thermoplastic resins can be used. Examples of thermoplastic resins include polyolefins such as polyethylene, polypropylene, and polybutene; polyesters such as polyethylene terephthalate and polybutylene terephthalate; polyamides such as nylon 6 and nylon 66; polyacrylic acid; polymethacrylic acid alkyl esters; polyvinyl chloride; and polyvinylidene chloride. These resins can be used alone or as a blend of two or more. They can also be used in the form of composite fibers such as core-sheath and side-by-side types.

[0015] 1, the topsheet 10 of this embodiment has a plurality of protrusions 5 protruding from one side of the topsheet 10 in areas adjacent to the through-holes 6. Specifically, at least a portion of the first sheet 1 other than the through-holes 6 forms a plurality of protrusions 5 protruding to the side opposite the second sheet 2 side. The protrusions 5 and through holes 6 are arranged alternately in a row in the X direction, which is a direction parallel to the surface of the topsheet 10, and multiple such rows are formed in the Y direction, which is a direction parallel to the surface of the topsheet 10 and perpendicular to the X direction. The protrusions 5 and through holes 6 in adjacent rows are each arranged with a shift in the X direction, more specifically, with a shift of half a pitch.

[0016] In the topsheet 10 of this embodiment, the Y direction is parallel to the flow direction (machine direction, hereinafter also referred to as "MD") during production, and the transverse direction Q in the absorbent article described below is parallel to the direction (hereinafter also referred to as "CD") perpendicular to MD during production. Furthermore, the rotation axes of the uneven roll 31 (first roll) and the uneven roll 32 (second roll) described below are parallel to the CD and perpendicular to MD.

[0017] The topsheet 10 of this embodiment has a large number of recesses 3 sandwiched between protrusions 5 in both the X and Y directions on the surface facing the first sheet 1, and a through hole 6 is formed at the bottom of each recess 3. When viewed as a whole, the surface of the top sheet 10 has large irregularities on the side of the first sheet 1, consisting of the recesses 3 and the protrusions 5, while the surface on the side of the second sheet 2 is flat or an approximately flat surface with relatively small irregularities compared to the surface on the side of the first sheet 1.

[0018] In the topsheet 10 of this embodiment, the protrusions 5 and the through-holes 6 each have a shape that is long in the Y direction in plan view (see FIG. 1). Each through-hole 6 has a generally rectangular shape in plan view that is elongated in the Y direction. The topsheet 10 has a fused portion (not shown) along part of the open edge of the through-hole 6, where the first sheet 1 and the second sheet 2 are fused to each other, on the outside of the open edge. In such a fused portion, the heat-fusible resin of the constituent fibers of at least one of the first sheet 1 and the second sheet 2 is melted and solidified, thereby joining the first sheet 1 and the second sheet 2. The top sheet 10 has a valve membrane 20 at a part of the opening end of the through-hole 6 in a plan view. The valve membrane 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. The through-hole 6 of this embodiment has a pair of valve membranes 20a, 20b located on either side of the through-hole 6 in the longitudinal direction (Y direction), as shown in FIG. The valve membrane body 20 is connected to the first sheet 1 and the second sheet 2 at a portion of the opening end of the through hole 6, and extends toward the inward side of the through hole 6 in a planar view, with the connected portion (a portion of the opening end of the through hole 6) as its base end (see Figure 3).

[0019] The valve membrane body 20 is a film-like portion formed by melting and solidifying the heat-sealing resin that constitutes the first sheet 1 and the second sheet 2. That is, in the valve membrane body 20, the fiber material that constitutes the first sheet 1 and the second sheet 2 does not maintain its fibrous form when visually inspected, and appears to be a film.

[0020] The valve body 20 is capable of hinge movement. Specifically, the valve body 20 can rotate in the thickness direction Z of the top sheet 10 around a portion of the opening end of the through-hole 6 in the top sheet 10. As described above, the valve body 20 is a film-like portion formed by melting and solidifying the constituent fibers of the first sheet 1 and the second sheet 2. Therefore, the boundary between the film-like portion and the non-film-like portion (the portion where the constituent fibers maintain their fibrous form) is a "portion of the opening end" where the valve body 20 is located. The base-side edge of the valve body 20 forms a portion of the opening end of the through-hole 6, and is connected to the first sheet 1 and the second sheet 2 at this portion of the opening end. Hereinafter, this base-side edge will be simply referred to as the "base-side edge portion 21." The base-side edge portion 21 is located at a portion of the opening end of the through-hole 6. For example, when a load is applied to the valve body 20 from the skin-facing side, the valve body 20 rotates toward the non-skin-facing side around an axis that is a part of the open end of the through-hole 6. Furthermore, when the load on the valve body 20 is released, the valve body 20 that rotated toward the non-skin-facing side rotates toward the skin-facing side around an axis that is a part of the open end of the through-hole 6, and returns to its original position.

[0021] The topsheet 10 is disposed on the skin-facing side of the absorbent body, which is the main liquid-absorbing portion, in absorbent articles such as disposable diapers. The topsheet 10 comes into contact with the wearer's skin when the absorbent article is worn. In this specification, the "skin-facing side" refers to the side of an absorbent article or a component thereof (e.g., an absorbent body) that faces the skin of the wearer when the absorbent article is worn, i.e., the side that is relatively closer to the wearer's skin, and the "non-skin-facing side" refers to the side of an absorbent article or a component thereof that faces the opposite side from the skin side (the clothing side) when the absorbent article is worn, i.e., the side that is relatively farther from the wearer's skin. Note that "when worn" here refers to a state in which the normal, proper wearing position is maintained, and does not include a state in which the absorbent article is displaced from the proper wearing position.

[0022] In an absorbent article equipped with the topsheet 10 of this embodiment, when urine or loose stool is excreted, the excrement passes through the through-holes 6 in the topsheet 10 to the non-skin-facing side of the topsheet 10. When the excrement e reaches the hingeable valve body 20 in this topsheet 10, the weight of the excrement e is applied to the valve body 20. Furthermore, when the wearer's posture changes, body pressure applies an external force greater than the weight of the excrement e to the valve body 20. The weight of the excrement e and the body pressure (external force) cause the valve body 20 to rotate to the non-skin-facing side of the topsheet 10, allowing the excrement e to smoothly pass to the non-skin-facing side of the topsheet 10 (see Figure 4). Furthermore, when the excrement e migrates to the non-skin-facing side of the topsheet 10, the valve membrane body 20 rotates to its original position and becomes interposed between the excrement e on the non-skin-facing side and the skin, preventing the excrement e from coming into contact with the skin (see Figure 4). Furthermore, even if the topsheet 10 is compressed in the thickness direction Z due to the wearer's body pressure or the like, the valve membrane body 20 prevents the excrement e from returning to the skin-facing side of the topsheet 10. In this way, the valve membrane body 20 functions as a check valve that allows the excrement e to migrate from the skin-facing side to the non-skin-facing side, so the topsheet 10 can prevent the excrement from coming into contact with the skin while maintaining the permeability of the excrement.

[0023] The valve body 20 in the top sheet 10 can be confirmed by observing the through-hole 6 from either side of the top sheet 10 using an electron microscope (for example, manufactured by JEOL Ltd., model number: JCM-6000Plus) or a microscope (for example, manufactured by Keyence Corporation, model number: VHX-1000). When the top sheet 10 has a protrusion 5 protruding from either side, the through-hole 6 is observed from the side opposite to the side from which the protrusion 5 protrudes. Observation is performed at a magnification of 60x. The valve body 20 is a film-like region formed at part of the open end of the through-hole 6 that is capable of hinge action, and has an area of ​​1mm 2 This is the area where it is.

[0024] From the viewpoint of facilitating the rotation of the valvular body 20 and smoothing the transfer of excrement e to the non-skin-facing side, it is preferable that when a load is applied partially to the valvular body 20 from the skin-facing side, the entire valvular body 20 can rotate around an axis that is a part of the open end of the through-hole 6. When the valvular body 20 has such a configuration, for example, if an imaginary line is assumed that bisects the entire length of the base end edge 21 and extends in the extension direction (Y direction) of the valvular body 20, the entire valvular body 20 will rotate around an axis that is a part of the open end, regardless of where on the imaginary line a load is applied. In this way, it is preferable that the entire valvular body 20 can rotate even when the load applied to the valvular body 20 is partial.

[0025] The topsheet 10 of this embodiment has convex portions 5 in areas adjacent to the through-holes 6, and the valve membrane bodies 20 extend from the bottom of the convex portions 5 toward the inside of the through-holes 6 (see Figures 4 and 5). This configuration makes it easier for excrement to reach the valve membrane bodies 20 along the convex portions 5, more effectively preventing excrement from coming into contact with the skin. In this embodiment, the bottom of the convex portions 5 is formed by the second sheet 2, and the non-skin-facing surface of the second sheet 2 and the non-skin-facing surface of the valve membrane bodies 20 are continuous in the planar direction.

[0026] 3, the valve body 20 has a free edge 22 located on the opposite side of the base edge 21, and a pair of side edges 23, 23 located between the base edge 21 and the free edge 22. When the valve body 20 performs a hinged movement, it rotates around a part of the open end of the through-hole 6 as an axis so that the free edge 22 faces the skin-facing side or the non-skin-facing side. From the viewpoint of smoother hinge action of the valve membrane body 20, it is preferable that the pair of side edges 23, 23 are not connected to the opening end of the through-hole 6. In other words, it is preferable that the pair of side edges 23, 23 are not continuous with the opening end of the through-hole 6. In this embodiment, the pair of side edges 23, 23 are not connected to the opening end of the through-hole 6, which is opposite the side edge 23 (see FIG. 3 ). With this configuration, the movement of the valve membrane body 20 is not restricted by the side edge portions 23, 23, so that when a load is applied to the skin-facing side or the non-skin-facing side, the valve membrane body 20 can more easily rotate about a part of the opening end of the through-hole 6 as an axis. The side edges 23, 23 are edges connected to both ends of the base edge 21 in a plan view of the valve body 20, and are edges that form an angle of 60 degrees or more with respect to the base edge 21. The free edge 22 is an edge that forms the tip of the valve body 20 during its hinge action, and is an edge that forms an angle of less than 60 degrees with respect to the base edge 21.

[0027] From the viewpoint of achieving both the permeability of excrement and the function of the valve element 20 as a check valve, it is preferable that the dimensions of the valve element 20 be within the following ranges. The area of ​​the valve body 20 is preferably 5% or more, more preferably 10% or more, and is preferably 50% or less, more preferably 40% or less, and is preferably 5% or more and 50% or less, more preferably 10% or more and 40% or less, of the area of ​​the through hole 6. The area of ​​the through hole 6 is preferably 1 mm 2 More than 2mm, preferably 2 More than 10 mm, preferably 2 Less than 5mm, preferably 2 less than 1 mm, and preferably 2 More than 10mm 2Less than 2mm, preferably 2 Over 8mm 2 The following is the result. The area of ​​the valve body 20 is preferably 0.5 mm 2 More than 1mm, preferably 1mm 2 More than 5 mm, preferably 2 Less than 2.5mm, preferably 2 It is preferably 0.5 mm or less. 2 More than 5mm 2 Less than 1mm, preferably 2 Over 2.5mm 2 The following is the result. The area of ​​the through-hole 6 is the opening area when the valve bodies 20 are removed from the through-hole 6, leaving only the through-hole 6. The area of ​​the valve bodies 20 is the area of ​​one valve body 20. These areas are calculated as the average value of the areas of 10 arbitrarily selected through-holes 6 or the average value of the areas of 10 arbitrarily selected valve bodies 20 in a measurement piece (100 mm square) cut out from an arbitrary location on the topsheet 10.

[0028] The maximum length L (see Figure 3) of the valve body 20 in the extension direction (Y direction) is preferably 10% or more, more preferably 20% or more, and preferably 50% or less, more preferably 40% or less, relative to the length of the base end edge portion 21 (L / W1), and is preferably 10% or more and 50% or less, more preferably 20% or more and 40% or less. The maximum length L (see Figure 3) of the valve body 20 in the extension direction (Y direction) is preferably 1 mm or more, more preferably 2 mm or more, and is preferably 5 mm or less, more preferably 4 mm or less, and is preferably 1 mm or more and 5 mm or less, more preferably 2 mm or more and 4 mm or less. The length W1 of the base end edge 21 (see Figure 3) is preferably 1 mm or more, more preferably 2 mm or more, and is preferably 10 mm or less, more preferably 5 mm or less, and is preferably 1 mm or more and 10 mm or less, more preferably 2 mm or more and 5 mm or less.

[0029] The longitudinal length L6 of the through hole 6 is preferably 1 mm or more, more preferably 2 mm or more, and is preferably 15 mm or less, more preferably 10 mm or less, and is preferably 1 mm or more and 15 mm or less, more preferably 2 mm or more and 10 mm or less. The length W6 of the through hole 6 in the direction perpendicular to the longitudinal direction is preferably 1.5 mm or more, more preferably 2.5 mm or more, and is preferably 11 mm or less, more preferably 6 mm or less, and is preferably 1.5 mm or more and 11 mm or less, more preferably 2.5 mm or more and 6 mm or less.

[0030] 3, the topsheet 10 of this embodiment has a pair of valve bodies 20a, 20b arranged opposite each other on either side of the through-hole 6 in the longitudinal direction (Y direction). The pair of valve bodies 20a, 20b have different shapes. Specifically, the free edge portion 22 of one valve body 20a is curved in a convex shape that curves inward of the through-hole 6, while the free edge portion 22 of the other valve body 20b has a zigzag wave shape.

[0031] From the viewpoint of smoother hinge action and further improving the check valve function of the valve membrane body 20, it is preferable that the free edge portion 22 has a wavy shape in plan view. In this form, the position of the outline forming the free edge portion 22 has an uneven shape that changes alternately on the side approaching the base edge portion 21 and the side moving away from the base edge portion 21. From the same viewpoint as above, it is preferable that the meandering length L2 (not shown) of the free end edge portion 22 and the length W1 of the base end edge portion 21 are within the following ranges. The ratio (L2 / W1) of the serpentine length L2 of the free edge 22 to the length W1 of the base edge 21 is preferably greater than 1, more preferably greater than 2, and is preferably less than 10, more preferably less than 5, and is preferably greater than 1 but less than 10, more preferably greater than 2 but less than 5. The meandering length L2 of the free edge 22 is measured, for example, by performing image processing on an electron microscope image of the valve body 20 in a planar view. Such image processing uses a multipoint distance measurement menu that is implemented by default in the software "Keyence VHX-1000." For example, the meandering length L2 of the free edge 22 can be measured by tracing the free edge 22 on an electron microscope image (magnification: 60x).

[0032] When the free edge 22 has a wavy shape in plan view, the valve body 20b has an outline that forms the free edge 22 that has an uneven shape. When the valve body 20b having such a free edge 22 is viewed along the longitudinal direction (X direction) of the base edge 21, concave and convex portions are arranged alternately to form a wavy shape. The number of vertices of the convex portions in this valve body 20b is preferably 2 to 20, more preferably 5 to 10. When the number of vertices of the convex portions is within this range, each convex portion functions as a single valve, thereby further improving the check valve function of the valve body 20b. On the other hand, if the number of vertices of the convex portions is too large, the unevenness of the free edge 22 becomes too fine, making it difficult for each convex portion in the valve body 20 to function as a single valve.

[0033] The number of apexes of the convex portions of the valve membrane body 20b having the wavy free edge portion 22 is determined by the following method: First, for each convex portion of the valve membrane body 20b, the degree of protrusion La of the convex portion is determined by the following formula. La={(L10-L11)+(L10-L12)} / 2 L10: Distance between the apex of the convex portion and the base end edge portion 21 L11: Distance between the bottom of one recess adjacent to the protrusion and the base edge 21 L12: Distance between the bottom of the other recess adjacent to the protrusion and the base edge 21 Next, the number of convex portions whose degree of protrusion La is more than 5% of the longitudinal length L6 of the through-hole 6 is counted. When viewed along the longitudinal direction of the base end edge portion 21, the number of convex portions located at both ends in that direction is also counted. The sum of the number of convex portions counted in this way is defined as the "number of convex vertices." The distances L10, L11, and L12 (see FIG. 3) are measured, for example, by performing the image processing (menu for measuring distances between multiple points) described above on an electron microscope image of the valve body 20 in a plan view. For example, by selecting the apex of the convex portion forming the uneven shape of the free edge portion 22 and the base edge portion 21 in the electron microscope image (magnification: 60x), the distance between the apex of the convex portion and the base edge portion 21 can be measured.

[0034] The valve body 20 may have a constant thickness or may have a thickness that varies depending on the position. From the viewpoint of ensuring the strength of the valve body 20, the minimum thickness t1 (see FIG. 5) of the valve body 20 is preferably 10 μm or more, more preferably 20 μm or more, and is also preferably 1 mm or less, more preferably 500 μm or less, and is also preferably 10 μm or more and 1 mm or less, more preferably 20 μm or more and 500 μm or less.

[0035] From the viewpoint of smoother hinge movement toward the non-skin-facing surface, improving permeability of excrement, and further suppressing contact of excrement with the skin, it is preferable that the valve body 20 has a thick portion 25 on the proximal edge 21 side that is thicker than other portions (see FIG. 5). The "proximal edge 21 side" refers to the region on the proximal edge 21 side when the entire length of the valve body 20 in the extension direction is divided into two equal parts, and preferably refers to the region closest to the proximal edge 21 when the entire length of the valve body 20 in the extension direction is divided into three equal parts. It is even more preferable that the valve body 20 has a thick portion 25 in a position adjacent to the proximal edge 21. Examples of configurations having a thick portion 25 on the base end edge 21 side include a configuration in which the thickness gradually increases from the free end edge 22 toward the base end edge 21 in the cross section in the extension direction of the valve membrane body 20, and a configuration in which there is a locally thickened portion at one end on the base end edge 21 side.

[0036] From the same viewpoint as above, it is preferable that the maximum thickness t2 of the thick portion 25 (see FIG. 5) is within the following range: The maximum thickness of the thick portion 25 corresponds to the maximum thickness of the valve membrane body 20. The minimum thickness t1 of the valve body 20 (see Figure 5) is preferably 0.5% or more, more preferably 1% or more, and preferably 10% or less, more preferably 5% or less, relative to the maximum thickness t2 of the thick portion 25 (see Figure 5), as expressed by (t1 / t2), and is preferably 0.5% or more and 10% or less, more preferably 1% or more and 5% or less. The maximum thickness t2 (see FIG. 5) of the thick portion 25 is preferably 20 μm or more, more preferably 200 μm or more, and is preferably 1.1 mm or less, more preferably 600 μm or less, and is preferably 20 μm or more and 1.1 mm or less, more preferably 200 μm or more and 600 μm or less.

[0037] The minimum thickness t1 of the valvular body 20 and the thickness t2 of the thick portion 25 are measured using the following method. First, the top sheet 10, including the through-holes 6 and valvular body 20, is cut using a razor blade or similar tool along the extension direction of the valvular body 20, i.e., from the base edge 21 toward the free edge 22. When cutting the top sheet 10, the cutting line should extend in one direction (e.g., the Y direction) through the apex of the convex portion 5. If the concave-convex structure is significantly deformed by the pressure of the razor blade during cutting, the top sheet 10 is immersed in liquid nitrogen and then quickly cut. Next, the cut surface is observed under an electron microscope (magnification 200x) to measure the minimum thickness of the valvular body 20 and the thickness of the thick portion 25. This measurement is performed on 10 valvular bodies 20, and the average values ​​are taken as the minimum thickness of the valvular body 20 and the thickness of the thick portion 25.

[0038] As described above, the topsheet 10 of this embodiment has valve bodies 20a, 20b of different shapes in the through-hole 6 that is long in the Y direction. The shapes of the through-hole 6 and the valve body 20 are not limited to this. Figures 6(a) to (j) show variations of the through-hole 6 and the valve body 20. The through holes 6 shown in Figures 6(a) to (e) have a rectangular shape that is long in the Y direction. The through holes 6 shown in Figures 6(f) to (h) have an elliptical shape that is long in the X or Y direction. The through holes 6 shown in Figures 6(i) and (j) have a diamond shape. In the configurations shown in Figures 6(a), (c), (f), and (i), a single valve body 20 is provided in one through-hole 6. In the configurations shown in Figures 6(b), (d), (e), (g), (h), and (j), a single through-hole 6 has two or more valve bodies 20. In the configurations shown in Figures 6(b), (d), (e), (g), and (h), the multiple valve bodies 20 have the same shape. On the other hand, in the configuration shown in Figure 6(j), the multiple valve bodies 20 have different shapes. In the configurations shown in Figures 6(b), (g), (h), and (j), a pair of valve bodies 20 are arranged opposite each other on both sides of the longitudinal direction (Y direction or X direction) of the through-hole 6. In the configurations shown in Figures 6(d) and (e), a pair of valve bodies 20 are arranged opposite each other on both sides of the direction (X direction) perpendicular to the longitudinal direction of the through-hole 6. In the configurations shown in Figures 6(a) and (e), the free edge portion 22 of the valve membrane body 20 has a wavy line shape. On the other hand, in the configurations shown in Figures 6(b), (c), (f), (g), and (h), the free edge portion 22 of the valve membrane body 20 has a straight line shape that follows the base edge portion 21 or a curved shape that protrudes in a direction away from the base edge portion 21.

[0039] The valve membrane body 20 may be formed in all of the through-holes 6 in the top sheet 10, or may be formed in some of the through-holes 6. From the viewpoint of further improving the permeability of excrement in the top sheet 10 and further suppressing contact of excrement with the skin, the number of through holes 6 in which valve membrane bodies 20 are formed per unit area (the area of ​​a square region 10 mm on each side in a plan view) in the top sheet 10 is preferably 30% or more, more preferably 50% or more, of the total number of through holes 6 per unit area, and it is even more preferable that valve membrane bodies 20 are formed in all through holes 6. From the same viewpoint as above, the number of through holes 6 in which valve bodies 20 are formed per unit area (the area of ​​a square region 10 mm on each side in a plan view) in the surface sheet 10 is preferably 1 or more, more preferably 4 or more, and preferably 20 or less, more preferably 15 or less.

[0040] From the viewpoint of feel and cushioning, the topsheet 10 of this embodiment preferably has the following configuration. The height H of the convex portion 5 (see FIG. 5) is preferably 1 mm or more, more preferably 3 mm or more, and is preferably 10 mm or less, more preferably 6 mm or less, and is preferably 1 mm or more and 10 mm or less, more preferably 3 mm or more and 6 mm or less. The unit area of ​​the surface sheet 10 (1 cm 2 The number of protrusions 5 per 100 mm diameter portion is preferably 1 or more, more preferably 6 or more, and is preferably 20 or less, more preferably 15 or less, and is preferably 1 to 20, more preferably 6 to 15. The bottom area of ​​the protrusion 5 is preferably 0.5 mm 2 More than 2mm, preferably 2 More than 50 mm, preferably 2 Less than 20mm, preferably 2 It is preferably 0.5 mm or less. 2 More than 50mm 2 Less than 2mm, preferably 2 More than 20mm 2 The following is the result.

[0041] The topsheet 10 of this embodiment is preferably used as a topsheet provided in absorbent articles such as disposable diapers, sanitary napkins, panty liners, incontinence pads, etc. In particular, it is preferable that the first sheet 1 of the topsheet 10 forms the surface facing the wearer's skin (skin-facing surface), and the second sheet 2 forms the surface facing the absorbent body when worn (non-skin-facing surface).

[0042] An absorbent article equipped with the absorbent article topsheet of the present invention will be described below based on its preferred embodiments. Figures 7 and 8 show a flat-type disposable diaper 11, which is one embodiment of the absorbent article of the present invention. The diaper 11 is equipped with the topsheet 10 of the above-mentioned embodiment. The diaper 11 has a longitudinal direction P corresponding to the front-to-back direction of the wearer and a transverse direction Q perpendicular thereto, and is equipped with a liquid-retentive absorbent body 14 and a topsheet 10 arranged closer to the wearer's skin than the absorbent body 14.

[0043] As shown in Fig. 7, the diaper 11 has a crotch portion B, which is disposed in the crotch region of the wearer, and a ventral portion A and a dorsal portion C, which extend in front and behind the crotch portion. The ventral portion A, the crotch portion B, and the dorsal portion C may correspond to three equal regions when the diaper 11 is divided into three equal parts in the longitudinal direction P. The crotch portion B has a portion facing excretory parts, which is disposed facing the wearer's excretory parts such as the penis and anus when the diaper 11 is worn, and this portion facing excretory parts is usually located at or near the center of the diaper 11 in the longitudinal direction P.

[0044] 8, the diaper 11 comprises a topsheet 10, a liquid-permeable sublayer 15, and a liquid-retentive absorbent body 14 laminated in this order from the closest to the wearer's skin. More specifically, the diaper 11 comprises an absorbent body 14, a topsheet 10 disposed on the skin-facing side of the absorbent body 14 and overlapping the absorbent body 14 at a position closer to the wearer's skin than the absorbent body 14, a backsheet 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 wearer's skin than the absorbent body 14, and a sublayer 15 interposed between the topsheet 10 and the absorbent body 14.

[0045] The topsheet 10 and the backsheet 13 are larger than the sublayer 15 and the absorbent body 14, which are disposed between the topsheet 10 and the backsheet 13, respectively, and form the outer shape of the diaper 11 in the unfolded and stretched state as shown in FIG. The absorbent body 14 has an elongated shape in the longitudinal direction P, extending from the ventral portion A to the dorsal portion C. The absorbent body 14 is composed of a liquid-retentive absorbent core 140 and a core wrap sheet 141 that covers the outer surface of the absorbent core 140. The absorbent core 140 is typically made of a fiber assembly mainly composed of hydrophilic fibers such as wood pulp, and may further include water-absorbent polymer particles supported on the fiber assembly. The core wrap sheet 141 is typically made of paper, nonwoven fabric, or the like. As the backsheet 13, various materials conventionally used in this type of absorbent article can be used without any particular limitation, and examples thereof include a resin film and a laminate of a resin film and a nonwoven fabric.

[0046] The diaper 11 of this embodiment includes a sublayer 15 as a fibrous sheet disposed on the non-skin-facing side of the topsheet 10. The sublayer 15 serves to improve the permeability of liquid from the topsheet 10 to the absorbent body 14 and to reduce the return of liquid absorbed by the absorbent body 14 to the topsheet 10, and covers substantially the entire skin-facing side of the absorbent body 14. The topsheet 10, sublayer 15, absorbent body 14 (absorbent core 140, core wrap sheet 141) and backsheet 13 are joined together by known joining means such as adhesives.

[0047] The sublayer 15 of this embodiment has a plurality of recesses 151 and protrusions 152. Specifically, the sublayer 15 has a plurality of hollow protrusions 152 that protrude toward the skin-facing surface, and recesses 151 located between the plurality of protrusions 152. The non-skin-facing surface of the sublayer 15 has an uneven shape that corresponds to the uneven shape of the skin-facing surface. The sublayer 15 has a plurality of recesses 151 and protrusions 152 arranged alternately and continuously along the longitudinal direction P and the transverse direction Q. The sublayer 15 has a plurality of protrusions 152 protruding toward the skin-facing surface and having internal spaces, and recesses 151 located between the plurality of protrusions 152. The sublayer 15 also has a plurality of non-skin-side protrusions 153 protruding toward the non-skin-facing surface and having internal spaces, and non-skin-side recesses 154 located between the plurality of non-skin-side protrusions 153. The uneven shape of the skin-facing surface formed by the protrusions 152 and recesses 151 in the sublayer 15 corresponds to the uneven shape of the non-skin-facing surface formed by the non-skin-side protrusions 153 and non-skin-side recesses 154 in the sublayer 15. An example of a sublayer 15 having such a configuration is an intermediate sheet described in JP 2019-97678 A.

[0048] From the viewpoint of further improving the transfer of excrement to the absorber 14, it is preferable that the through-holes 6 and the valve membrane body 20 of the topsheet 10 at least partially overlap with the recesses 151 in the sublayer 15 (see FIG. 9). This makes it easier for excrement that passes through the through-holes 6 to enter the recesses 151 in the sublayer 15. To further improve the above-mentioned effects, the depth of the recesses 151 in the sublayer 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 also 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 recesses 151 is measured under no load by observing a cross section of the sublayer 15 in the thickness direction with a microscope.

[0049] The sublayer 15 can be a hydrophilic and liquid-permeable sheet. Specific examples include paper, woven fabric, and nonwoven fabric. However, nonwoven fabric is particularly preferred because of its relatively high strength and excellent flexibility. While the sublayer 15 of this embodiment has a single-layer structure, the sublayer 15 may alternatively have a multilayer structure formed by laminating multiple layers. The uneven shape of the sublayer 15 can be, for example, a cone, a truncated cone, a pyramid, a truncated pyramid, or an oblique cone. A sublayer 15 having an uneven shape can be produced, for example, by placing a raw nonwoven fabric (e.g., an air-through nonwoven fabric) on a support having numerous protrusions, and then blowing hot air onto the raw nonwoven fabric on the support to form an uneven shape. Examples of methods for producing such a sublayer 15 include those described in JP 2013-133574 A, JP 2012-149370 A, JP 2012-149371 A, and the like.

[0050] 7 and 8, the diaper 11 includes a pair of leakage-barrier cuffs 16, 16 arranged along both ends of the absorbent body 14 in the transverse direction Q and standing up toward the wearer's skin at least in the crotch region B when the diaper 11 is worn. Each leakage-barrier cuff 16 includes a liquid-resistant or water-repellent and breathable leakage-barrier sheet 160, one end of which in the transverse direction Q is fixed to another member (e.g., a topsheet or a backsheet) as a fixed end, and the other end in the transverse direction Q as a free end that is not fixed to another member. A leakage-barrier-forming elastic member 161 is arranged at the free end of the leakage-barrier sheet 160 and is fixed in a stretched state in the longitudinal direction P, allowing it to stretch in the same direction. When the diaper 11 is worn, the contractile force of the elastic members 161 causes the free end of the leak-barrier sheet 160 to stand toward the wearer with the fixed end as the standing base, at least in the crotch region B, thereby standing up the pair of leak-barrier cuffs 16, 16, thereby preventing urine and other excrement from leaking outward in the lateral direction Q. As the leak-barrier sheet 160, any material that is used as a leak-barrier cuff material in this type of absorbent article can be used without any particular limitation, and a material that is liquid-resistant or water-repellent and breathable is preferred, and examples that can be used include single-layer or multi-layer water-repellent nonwoven fabrics, and laminates of resin films and nonwoven fabrics, etc.

[0051] As shown in Figure 7, thread-like elastic members 17 are fixed in a stretched state in the longitudinal direction P between the leakproof sheet 160 and the backsheet 13 in the left and right leg portions that are disposed around the wearer's legs, so that when the diaper 11 is worn, a pair of leg gathers are formed in the leg portions by contraction of the elastic members 17. The topsheet 10, sublayer 15, backsheet 13, absorbent body 14, leakproof sheet 160 and elastic members 161 are joined together by known joining means such as a hot-melt adhesive.

[0052] As shown in Figure 7, a pair of fastening tapes 18, 18 is provided on both side edges of the back portion C of the diaper 11 along the longitudinal direction P. A fastening portion consisting of a male member of a mechanical hook-and-loop fastener is attached to the fastening tape 18. A fastening region 19 consisting of a female member of the mechanical hook-and-loop fastener is formed on the non-skin-facing surface of the abdominal portion A of the diaper 11. The fastening region 19 is formed by joining and fixing the female member of the mechanical hook-and-loop fastener to the non-skin-facing surface of the backsheet 13, which forms the non-skin-facing surface of the abdominal portion A, by a known joining means such as adhesive or heat sealing, so that the fastening portion of the fastening tape 18 can be detachably fastened.

[0053] Next, a method for manufacturing the topsheet for absorbent articles of the present invention will be described using the method for manufacturing the topsheet 10 of the above-mentioned embodiment as an example. Figure 10 shows a manufacturing apparatus 100, which is one embodiment of the manufacturing apparatus for the topsheet for absorbent articles of the present invention. The manufacturing apparatus 100 includes a concavo-convex shaping section 30 and an ultrasonic processing section 40.

[0054] The unevenness forming unit 30 includes an uneven roll 31 having unevenness on its peripheral surface. In the unevenness forming unit 30, the first sheet 1 is caused to follow the peripheral surface of the rotating uneven roll 31, thereby deforming the first sheet 1 into an uneven shape that conforms to the uneven shape of the peripheral surface.

[0055] The uneven shaping unit 30 includes, in addition to the uneven roll 31, another uneven roll 32 having unevenness on its peripheral surface that engages with the unevenness of the uneven roll 31. Hereinafter, the uneven roll 31 will also be referred to as the "first roll" and the uneven roll 32 will also be referred to as the "second roll." In the uneven shaping section 30 shown in Figure 10, these two rolls 31, 32 are used, and both rolls 31, 32 are rotated so that an interlocking portion 33 between the uneven portions of both rolls 31, 32 is formed, and by introducing the first sheet 1 into the interlocking portion 33, the first sheet 1 is deformed into an uneven shape that follows the uneven shape of the peripheral surface of the uneven roll 31.

[0056] FIG. 11 shows a part of the peripheral surface of the uneven roll 31 (first roll). The uneven roll 31 is formed into a roll by combining a plurality of spur gears 31a, 31b, etc., each having a predetermined tooth width. The teeth of each gear form unevenly shaped convex portions 35 on the circumferential surface of the uneven roll 31, and the tip surfaces 35c of the convex portions 35 serve as pressure surfaces that press the first and second sheets 1 and 2 to be fused together with a vibration application surface 42t, which is the tip surface of an ultrasonic horn 42 of an ultrasonic fusion machine 41 described later.

[0057] The tooth width (axial length of the gear) of each gear that constitutes the uneven roll 31 determines the X-direction dimension of the protrusions 5 of the surface sheet 10, and the tooth length (length in the rotational direction of the gear) of each gear determines the Y-direction dimension of the protrusions 5 of the surface sheet 10. Adjacent gears are combined so that the tooth pitches of the gears are shifted by half a pitch, resulting in the uneven roll 31 having an uneven peripheral surface. In the illustrated embodiment, the tip surface 35c of each projection 35 has a rectangular shape with the long side in the rotation direction of the uneven roll 31 and the short side in the axial direction. It is preferable that the tip surface 35c has a shape that is longer in the direction of rotation, because this increases the contact time between one of the convex portions 35 of the uneven roll 31 and the vibration application surface 42t of the tip of the ultrasonic horn 42, making it easier to raise the temperature.

[0058] The recesses of each gear in the uneven roll 31 form recesses of the unevenness on the peripheral surface of the uneven roll 31 . A suction hole 34 is formed in the tooth bottom (bottom of the recess) of each gear. The suction hole 34 is connected to a suction source (not shown) such as a blower or a vacuum pump, and is controlled so that suction is performed from the meshing portion 33 between the concave-convex roll 31 and the concave-convex roll 32 to the joining portion of the first sheet 1 and the second sheet 2. Therefore, the first sheet 1, which has been deformed into an uneven shape by the meshing of the uneven roll 31 and the uneven roll 32, is maintained in a deformed state into a shape that follows the unevenness of the peripheral surface of the uneven roll 31 by the suction force of the suction holes 34, and is transported to the confluence of the first sheet 1 and the second sheet 2 and to the ultrasonic vibration application section 36 by the ultrasonic fusion machine 41. In the uneven roll 31 shown in Figure 11, a predetermined gap G is provided between adjacent gears, which prevents the first sheet 1 from being subjected to excessive stretching force or from being cut at the meshing portion 33 of the two rolls 31, 32, making it easier for the first sheet 1 to deform into an uneven shape that conforms to the shape of the peripheral surface of the uneven roll 31.

[0059] The uneven roll 32 (second roll) has an uneven shape on its peripheral surface that meshes with the unevenness on the peripheral surface of the uneven roll 31. The uneven roll 32 has the same configuration as the uneven roll 31, except that it does not have suction holes 34. Incidentally, the diameter of the concave-convex roll 31 and the diameter of the concave-convex roll 32 may be different, provided that the concave-convex portions of both rolls 31 and 32 mesh with each other. Then, by introducing the first sheet 1 into the meshing portion 33 of both rolls 31 and 32 while rotating both rolls 31 and 32 having meshing concave-convex portions, the first sheet 1 can be deformed into a concave-convex shape. At the interlocking portion 33, multiple locations of the first sheet 1 are pressed into the recesses on the peripheral surface of the uneven roll 31 by the convex portions of the uneven roll 32, and these pressed-in portions become the convex portions 5 of the top sheet 10 to be manufactured. The peripheral surface of the uneven roll 32 is formed with multiple convex portions that are inserted into the concave portions of the uneven roll 31, but it is not essential that the uneven roll 32 has convex portions that correspond to all of the concave portions of the uneven roll 31.

[0060] As described above, the uneven shaping unit 30 shown in FIG. 10 includes two uneven rolls with uneven surfaces on their peripheral surfaces. The two uneven rolls 31, 32 are rotated to form an interlocking portion 33 between the uneven surfaces of the two uneven rolls 31, 32, and the first sheet 1 is introduced into the interlocking portion 33, thereby deforming the first sheet 1 into an uneven shape. However, the uneven roll included in the uneven shaping unit 30 may be only the uneven roll 31 that can suck the first sheet 1 introduced into the peripheral portion; that is, the uneven roll 32 may be omitted. In this case, simply introducing the first sheet 1 onto the peripheral portion of the uneven roll 31 causes the first sheet 1 to deform to conform to the uneven shape of the peripheral portion due to the suction force of the suction holes 34 (see FIG. 11 ) arranged on the peripheral portion. Such conformance and deformation of the first sheet 1 due to suction at the peripheral portion of the uneven roll 31 can be achieved by appropriately adjusting the suction force and the arrangement of the suction holes 34.

[0061] The ultrasonic processing unit 40 is equipped with an ultrasonic fusion machine 41 equipped with an ultrasonic horn 42, and overlaps the second sheet 2 on the first sheet 1 in a state in which it has been deformed into a concave-convex shape, and then sandwiches the two sheets 1 and 2 between the convex portion 35 of the concave-convex roll 31 and the vibration application surface 42t at the tip of the ultrasonic horn 42 and applies ultrasonic vibrations, thereby forming a through-hole 6 and fusing the first sheet 1 and the second sheet 2. At this time, a fused portion where the first sheet 1 and the second sheet 2 are fused and a valve membrane body 20 are formed at the periphery (opening) of the through-hole 6.

[0062] As shown in FIGS. 10 and 12, the ultrasonic fusion machine 41 includes an ultrasonic oscillator (not shown), a converter 43, a booster 44, and an ultrasonic horn . An ultrasonic oscillator (not shown) is electrically connected to the converter 43 , and a high-voltage electrical signal with a wavelength of about 15 to 50 kHz generated by the ultrasonic oscillator is input to the converter 43 . An ultrasonic oscillator (not shown) is installed on the movable base 45 or outside the movable base 45 .

[0063] Converter 43 incorporates a piezoelectric element such as a piezoelectric element, and converts the electrical signal input from the ultrasonic oscillator into mechanical vibrations using the piezoelectric element. Booster 44 adjusts, preferably amplifies, the amplitude of the mechanical vibrations emitted from converter 43 and transmits them to ultrasonic horn 42. The ultrasonic horn 42 is made of a block of metal such as an aluminum alloy or titanium alloy, and is designed to resonate correctly at the frequency to be used. The ultrasonic vibrations transmitted from the booster 44 to the ultrasonic horn 42 are also amplified or attenuated inside the ultrasonic horn 42 and applied to the fusion targets, the first and second sheets 1 and 2. Such an ultrasonic fusion machine 41 can be a combination of a commercially available ultrasonic horn, converter, booster, and ultrasonic oscillator.

[0064] The ultrasonic fusion machine 41 is fixed on a movable table 45, and by moving the position of the movable table 45 back and forth in a direction approaching the peripheral surface of the uneven roll 31, it is possible to adjust the clearance between the vibration application surface 42t, which is the tip surface of the ultrasonic horn 42, and the tip surface 35c of the convex portion 35 of the first roll 31, as well as the pressure applied to the stacked first and second sheets 1 and 2. Then, the first and second sheets 1, 2 to be fused are sandwiched between the tip surfaces 35c of the convex portions 35 of the concave-convex roll 31 and the vibration application surface 42t of the tip of the ultrasonic horn 42 of the ultrasonic fusion machine 41 and pressurized while ultrasonic vibrations are applied to both sheets 1, 2, causing the portions of both sheets 1, 2 located on the tip surfaces 35c of the convex portions 35 to heat up. As a result, the first sheet 1 and / or the second sheet 2 melt and re-solidify, forming molten portions, and a through-hole 6 penetrating both sheets 1, 2 is formed surrounded by the molten portion. This molten portion becomes a fused portion along part of the opening edge of the through-hole 6. It is also thought that a valve membrane body 20 is formed from part of the molten portion by shear force, which will be described later.

[0065] The vibration application surface 42t at the tip of the ultrasonic horn 42 is made of the tip surface of the main body 420 (see Figure 12) of the ultrasonic horn 42, which is made of a metal such as an aluminum alloy or a titanium alloy, and abuts against the object to be fused, more specifically the second sheet 2.

[0066] The manufacturing apparatus 100 is provided with a preheating means 51 that preheats at least one of the first sheet 1 and the second sheet 2 before applying ultrasonic vibrations thereto. The preheating means 51 is disposed inside the concave-convex roll 31 (first roll) and extends parallel to the rotation axis (CD) of the concave-convex roll 31. A plurality of preheating means 51 are arranged around the rotation axis of the uneven roll 31 in the vicinity of the outer periphery at intervals in the circumferential direction. The preheating means 51 can be anything that can heat the object to be heated (first sheet 1, second sheet 2) by applying thermal energy from the outside, such as a cartridge heater using an electric heating wire, but is not limited to this and any of various known heating means can be used without any particular restrictions.

[0067] The preheating means 51 is a part of the preheating mechanism 50 . In addition to the preheating means 51, the preheating mechanism 50 is equipped with a temperature measuring means (not shown) capable of measuring the temperature of the object to be fused before applying ultrasonic vibrations, and a temperature control unit (not shown) that controls the temperature of the preheating means 51 based on the measurement value of the temperature measuring means. The temperature of the peripheral surface of the uneven roll 31 heated by the preheating means 51 is controlled by the temperature control unit. The preheating mechanism 50 can maintain the temperature of the first sheet 1 introduced into the ultrasonic vibration application unit 36 ​​within a predetermined range while the manufacturing apparatus 100 is in operation.

[0068] As shown in FIG. 13, the manufacturing apparatus 100 is provided with a horn heating means 61 for heating the ultrasonic horn 42 including the vibration application surface 42t. Horn heating means 61 is not disposed on vibration application surface 42t, but is fixed in the vicinity of vibration application surface 42t, specifically, to the side surface of the tip of ultrasonic horn 42. As the horn heating means 61, various known heating means such as a heater can be used without any particular restrictions.

[0069] The horn heating means 61 is a part of the horn heating mechanism 60 . In addition to the horn heating means 61, the horn heating mechanism 60 is equipped with a temperature measuring means (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 horn heating means 61 based on the measurement value of the temperature measuring means. The temperature control unit controls the heating temperature of the vibration application surface 42t by the horn heating means 61. The horn heating mechanism 60 can maintain the temperature of the vibration application surface 42t within a predetermined range while the manufacturing apparatus 100 is in operation.

[0070] The ultrasonic fusion machine 41 applies ultrasonic vibrations to the objects to be fused, thereby generating heat and melting the objects to fuse them, and is clearly distinguishable from the preheating means 51 and horn heating means 61 described above.

[0071] In the manufacturing apparatus 100, a groove-like recess 46 is formed on the vibration application surface 42t of the ultrasonic horn 42. Fig. 14 shows a schematic cross-sectional view along the MD of the tip of the ultrasonic horn 42, and Fig. 15 shows a schematic plan view of the vibration application surface 42t of the ultrasonic horn 42. Fig. 14 is an enlarged cross-sectional view of the tip of the ultrasonic horn 42 shown in Fig. 13. The groove-like recesses 46 extend along the rotation axis (CD) of the uneven roll 31 (first roll). Here, "extending along the rotation axis (CD)" means that the angle between the groove-like recesses 46 and the rotation axis (CD) of the uneven roll 31 is less than 45 degrees. The groove-like recesses 46 shown in Fig. 15 extend parallel to the rotation axis (CD), and the angle they form with the rotation axis (CD) is zero.

[0072] In the manufacturing apparatus 100, one groove-shaped recess 46 is formed on the vibration application surface 42t. As shown in Fig. 15, this one groove-shaped recess 46 is located in the center of the length of the vibration application surface 42t along the MD and extends over the entire length along the CD.

[0073] The groove-like recess 46 is defined by a pair of recess side surfaces 46a, 46a and a recess bottom surface 46b in a cross-sectional view taken along a direction perpendicular to the rotation axis of the uneven roll 31 (ie, MD) as shown in FIG. The pair of recess side surfaces 46a, 46a intersect with the vibration application surface 42t, more specifically, are connected to the vibration application surface 42t and extend in a direction away from the vibration application surface 42t. The recess bottom surface 46b is connected to each of the longitudinal ends of the pair of recess side surfaces 46a, 46a and faces the opening 46d of the groove-shaped recess 46. In the ultrasonic horn 42 shown in Figure 13 (Figure 14), the corner 46c where the recess side surface 46a and the vibration application surface 42t intersect is sharp, and the recess bottom surface 46b, when viewed in cross section along the MD, has an arc shape that is concave in the direction away from the opening 46d. In the embodiment shown in Fig. 13 (Fig. 14), the angle formed between 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.

[0074] The method for manufacturing the top sheet 10 using the manufacturing apparatus 100 configured as described above includes a shaping step in which an uneven roll 31 (first roll) having unevenness on its peripheral surface is rotated, and the first sheet 1 is caused to follow the peripheral surface and deformed into an uneven shape. In addition, the method for manufacturing the top sheet 10 using the manufacturing apparatus 100 includes a lamination process in which a first sheet 1 deformed into an uneven shape is conveyed while being held on an uneven roll 31, and a second sheet 2 is superimposed on the first sheet 1 during conveyance. In addition, the method for manufacturing the top sheet 10 using the manufacturing apparatus 100 includes an ultrasonic treatment step in which the overlapping sheets 1, 2 are sandwiched between the convex portion 35 of the uneven roll 31 and the vibration application surface 42t at the tip of the ultrasonic horn 42 provided in the ultrasonic fusion machine 41, and ultrasonic vibrations are applied.

[0075] In the shaping step, the first sheet 1 is introduced into an interlocking portion 33 between the concave and convex portions of the two concave and convex rolls 31 and 32, and the first sheet 1 is deformed into a concave and convex shape. From the viewpoint of making it easier to form the valve membrane body 20 and the through hole 6, the angle θ35 (see Figure 13) of the corner at the tip of the convex portion 35 in a cross-sectional view (cross-sectional view along MD) along a direction perpendicular to the rotation axis of the uneven roll 31 (first roll) is preferably 90 degrees or more, more preferably 105 degrees or more, and is also preferably less than 135 degrees, more preferably less than 120 degrees.

[0076] In the ultrasonic processing step, the specific ultrasonic horn described above is used as the ultrasonic horn, i.e., an ultrasonic horn 42 having a vibration application surface 42t on which a groove-like recess 46 extending along the rotation axis (CD) of the uneven roll 31 (first roll) is formed, and ultrasonic vibrations are applied to form a through hole 6 in the laminate (object to be fused) of the overlapping first sheet 1 and second sheet 2, and to form a fused portion where the first sheet 1 and the second sheet 2 are fused, and a valve membrane body 20 in the through hole 6.

[0077] In the ultrasonic treatment process, as shown in Figure 13, while the object to be fused (a laminate of a first sheet 1 and a second sheet 2) is transported to the MD, it is sandwiched between the tip surface 35c of the convex portion 35 of the uneven roll 31 and the vibration application surface 42t on which the groove-shaped concave portion 46 of the ultrasonic horn 42 is formed, and ultrasonic vibrations are applied. 14, the vibration application surface 42t that presses the fusion object toward the convex portion 35 has a pair of corners 46c, 46c located before and after the MD with the opening 46d of the groove-like recess 46 between them, so that the stress generated when pressing the fusion object is concentrated at the corner 46c, and the shear force applied to the fusion object via the corner 46c is stronger than when the corner 46c (groove-like recess 46) is not formed. Therefore, in the ultrasonic treatment step, in addition to the heating of the fusion object due to the ultrasonic vibration, a strong shear force caused by the groove-like recess 46 acts on the fusion object, and as a result, a fusion portion, a through-hole 6, and a valve membrane body 20 can be simultaneously formed in the part of the fusion object sandwiched between the tip surface 35c of the convex portion 35 and the vibration application surface 42t of the ultrasonic horn 42. According to the ultrasonic treatment process, even if the resin forming the first sheet 1 and / or the second sheet 2 has a high melting point exceeding 200°C (e.g., PET), it is possible to simultaneously form the fused portion, the through hole 6, and the valve membrane body 20.

[0078] In the ultrasonic treatment process, an ultrasonic horn (see FIGS. 13 to 15) having a groove-like recess formed on the vibration application surface extending along the rotation axis of the concave-convex roll was used, which is thought to facilitate the formation of the valve membrane body 20 at a portion of the opening end of the through-hole 6. The inventor's considerations regarding the method for forming this valve membrane body 20 are described below. In the ultrasonic treatment process, while conveying the fusion target (a laminate of the first sheet 1 and the second sheet 2) in the MD, ultrasonic vibrations are applied to the object by sandwiching it between the tip surface 35c of the convex portion 35 of the concave-convex roll 31 and the vibration application surface 42t of the ultrasonic horn 42 having a groove-like recess 46 formed thereon. This results in the formation of a fused portion in which the first sheet 1 and the second sheet 2 are melted. Meanwhile, stress generated when pressing the object to be fused is concentrated on the corner 46c located on the forward (downstream) side of the MD out of a pair of corners 46c, 46c located before and after the MD with the opening 46d of the groove-like recess 46 between them. Therefore, shear force acts on the object to be fused, particularly the fused portion, via the corner 46c. It is presumed that this shear force breaks the contact portions of the fusion object with the corners 46c, 46c on the front and rear sides in the MD, forming a through-hole 6, and the molten portion is stretched thinly along the MD, forming a valve membrane body 20 at a part of the opening end of the through-hole 6. In other words, the shear force along the MD forms the valve membrane body 20 at the opening end of the through-hole 6 on at least one or both of the front side (downstream side) and rear side (upstream side) in the flow direction (MD) during the production of the topsheet 10.

[0079] From the viewpoint of more easily forming the valve membrane body 20, in the ultrasonic treatment process, the pressure applied to the first and second sheets 1, 2 sandwiched between the tip surface 35c of the convex portion 35 of the concave-convex roll 31 (first roll) and the vibration application surface 42t of the ultrasonic horn 42 is preferably 10 N / mm or more, and more preferably 15 N / mm or more. The pressure is preferably 30 N / mm or less, and more preferably 25 N / mm or less. The "pressure" referred to here is the so-called linear pressure, and is expressed as the value (pressure per unit length) obtained by dividing the pressure (N) of the ultrasonic horn 42 by the total length (excluding the recesses of the uneven roll 31) of the tooth widths of the convex portions 35 that come into contact with the ultrasonic horn 42 (the length along the CD of the convex portions 35).

[0080] From the same viewpoint as above, the frequency of the applied ultrasonic vibration is preferably 15 kHz or higher, and more preferably 20 kHz or higher. The frequency is preferably 50 kHz or less, and more preferably 40 kHz or less. From the same viewpoint, the amplitude of the applied ultrasonic vibration is preferably 20 μm or more, and more preferably 25 μm or more. The amplitude is preferably 50 μm or less, and more preferably 40 μm or less. When measuring the frequency and amplitude of 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 higher and an accuracy of 1 μm or higher.

[0081] From the same viewpoint as above, the conveying speed of the fusion object (a laminate of the first sheet 1 and the second sheet 2) in the ultrasonic treatment process is preferably 50 m / min or more, more preferably 100 m / min or more, and is preferably 400 m / min or less, more preferably 300 m / min or less.

[0082] According to the ultrasonic horn 42 of this embodiment, as shown in Figure 14, the corners 46c that define the opening 46d of the groove-shaped recess 46 are sharp, and therefore the shear force applied to the fusion object (a laminate of the first sheet 1 and the second sheet 2) in the ultrasonic processing process is improved compared to when the corners 46c are rounded rather than sharp, and therefore the simultaneous formation of the fusion portion, the through hole 6 and the valve membrane body 20 can be more reliably carried out. To ensure that the corners 46c provide the desired effect, the angle formed between the recess side surface 46a at the corners 46c and the vibration application surface 42t is preferably 45 degrees or greater, and more preferably 60 degrees or greater. The angle is preferably 135 degrees or less, and more preferably 120 degrees or less.

[0083] On the other hand, if groove-like recesses 46 are formed on vibration application surface 42t of ultrasonic horn 42, there is a concern that the durability of ultrasonic horn 42 (particularly main body 420) will decrease and that, during ultrasonic vibration, cracks (fissures) will occur in main body 420, etc., originating from groove-like recesses 46. In contrast, in ultrasonic horn 42, such concerns are eliminated by making recess bottom surface 46b defining groove-like recesses 46 into an arc shape recessed in a direction away from opening 46d in a cross-sectional view along MD of ultrasonic horn 42 as shown in Figure 14. In order to ensure that the bottom surface 46b of the recessed portion exhibits the desired effect, the curvature of the bottom surface 46b of the recessed portion is preferably 1 or greater, and more preferably 2 or greater. The curvature of the bottom surface 46b of the recess is preferably 10 or less, and more preferably 5 or less.

[0084] In order to ensure that the above-described effects of the groove-shaped recess 46 are exhibited more reliably, it is preferable that the dimensions of the groove-shaped recess 46 be set as follows. The width W of the groove-like recess 46 (see FIGS. 14 and 15) is preferably 0.2 mm or more, and more preferably 0.5 mm or more. The width W is preferably 2 mm or less, and more preferably 1 mm or less. The width W0 (see FIG. 15) of the vibration applying surface 42t is preferably 5 mm or more, and more preferably 10 mm or more. The width W0 is preferably 20 mm or less, and more preferably 15 mm or less.

[0085] The ratio of the length of the groove-shaped recess 46 along the CD, i.e., the length L (see Figure 15) along the rotation axis of the uneven roll 31 (first roll), to the length L0 (see Figure 15) along the same direction of the vibration application surface 42t, as length L / length L0, is preferably 0.2 or more, and more preferably 0.3 or more. The ratio (length L / length L0) is preferably 1 or less. In the embodiment shown in FIG. 15, the groove-shaped recess 46 extends over the entire length CD of the vibration application surface 42t, and the length L and the length L0 are the same, so the ratio is 1. The length L0 of the vibration application surface 42t along CD is preferably 30 mm or more, and more preferably 50 mm or more. The length L0 is preferably 200 mm or less, and more preferably 150 mm or less.

[0086] The depth D of the groove-shaped recess 46 (see FIG. 14; the length from the vibration application surface 42t to the part of the recess bottom surface 46b farthest from the vibration application surface 42t) is preferably 0.3 mm or more, and more preferably 0.5 mm or more. The depth D is preferably 5 mm or less, and more preferably 2 mm or less. The groove-shaped recess 46 is preferably formed in the center of the MD of the vibration application surface 42t, and in particular, is preferably formed in an area within 5 mm, more preferably within 3 mm, upstream of the center of the MD of the vibration application surface 42t. In the embodiment shown in FIG. 15, the groove-shaped recess 46 is formed in the center of the MD of the vibration applying surface 42t.

[0087] As mentioned above, the manufacturing apparatus 100 is equipped with a preheating means 51 (preheating mechanism 50), and in the method for manufacturing the top sheet 10 using the manufacturing apparatus 100, at least one of the first sheet 1 and the second sheet 2 is preheated by the preheating means 51 before being subjected to the ultrasonic treatment process. This, combined with the effect of the groove-shaped recess 46, makes it possible to more reliably form the fused portion, the through hole 6, and the valve membrane body 20 simultaneously.

[0088] The conditions for preheating the objects to be fused by the preheating means 51 are not particularly limited and may be adjusted appropriately depending on the type of objects to be fused, but it is preferable to heat at least one of the first sheet 1 and the second sheet 2 to a temperature below the melting point of the sheet or to a temperature 50°C lower than the melting point. That is, prior to the application of ultrasonic vibrations, it is preferable to carry out either or both of the following (1) and (2): (1) The first sheet 1 is heated to a temperature lower than the melting point of the first sheet, or to a temperature 50° C. lower than the melting point. (2) The second sheet 2 is heated to a temperature lower than the melting point of the second sheet, but not lower than 50° C. below the melting point. Preferably, the first sheet 1 is heated to a temperature that is lower than the melting point of the first sheet but 50°C lower than the melting point, and the second sheet 2 is heated to a temperature that is lower than the melting point of the second sheet but 50°C lower than the melting point.

[0089] As an example of the method (1), i.e., a method of heating the first sheet 1 to a temperature lower than the melting point of the first sheet 1 and 50°C lower than the melting point, the temperature of the first sheet 1 on the uneven roll 31 (first roll) is measured between the meshing portion 33 of the uneven rolls 31, 32 and the ultrasonic vibration application portion 36 of the ultrasonic fusion machine 41, and the temperature of the preheating means 51 is controlled so that the measured value falls within the specific range described above. As a method of preheating the first sheet 1 to a temperature within a specific range, various methods can be used instead of a method of controlling the temperature of the peripheral surface of the uneven roll 31 using a heater arranged within the uneven roll 31 so that the first sheet 1 has a temperature within a specific range. For example, a method of installing a heater, hot air outlet, or far-infrared ray irradiation device near the peripheral surface of the uneven roll 31 and using these to control the temperature of the peripheral surface of the uneven roll 31 before or after the first sheet 1 is laid along it, or a method of heating the uneven roll 32 (second roll) that contacts the first sheet 1 at the meshing portion 33 and controlling the temperature of its peripheral surface to control the temperature of the first sheet 1, are included. Other methods include bringing the first sheet 1 into contact with a heated roller, passing it through a space maintained at a high temperature, or blowing hot air onto it before it is placed along the uneven roll 31.

[0090] As for the method (2) above, i.e., a method for heating the second sheet 2 to a temperature below the melting point of the second sheet 2 and at least 50°C lower than the melting point, it is preferable to measure the temperature of the second sheet 2 before it is merged with the first sheet 1 using a temperature measuring means arranged in the conveying path of the second sheet 2, and to control the temperature of a heating means (not shown) for the second sheet 2 arranged in the conveying path of the second sheet 2 so that the measured value falls within the specific range described above. The heating means for the second sheet 2 may be a contact type, such as contacting it with a heated roller, or a non-contact type, such as passing it through a space maintained at a high temperature, blowing hot air onto it, passing it through it, or irradiating it with infrared rays.

[0091] The melting points of the first sheet 1 and the second sheet 2 can be measured using, for example, a PYRIS Diamond DSC differential scanning calorimeter (DSC) manufactured by Perkin-Elmer, Inc. In this measurement method, the melting points of the objects to be measured (first sheet 1, second sheet 2) are determined from the peak value of the measurement data. When the first sheet 1 or the second sheet 2 is a fiber sheet such as a nonwoven fabric, and the constituent fibers are composite fibers consisting of multiple components such as core-sheath type or side-by-side type, the melting point of the sheet is the lowest melting point among the multiple melting points measured by DSC.

[0092] As mentioned above, the manufacturing apparatus 100 is equipped with a horn heating means 61 (horn heating mechanism 60), and in the ultrasonic treatment process, the vibration application surface 42t heated by the horn heating means 61 is brought into contact with the object to be fused (a laminate of the first sheet 1 and the second sheet 2), which, combined with the effect of the groove-shaped recess 46, makes it possible to more reliably form the fused portion, the through hole 6, and the valve membrane body 20 simultaneously.

[0093] The conditions for heating by the horn heating means 61 are not particularly limited, and may be adjusted appropriately depending on the type of material to be fused, etc. For example, the method (2) may be implemented by using a horn heating means 61 instead of the preheating means 51. That is, by controlling the temperature of the ultrasonic horn 42 (vibration application surface 42t) heated by the horn heating means 61, the temperature of the second sheet 2 immediately before the application of ultrasonic vibrations may be heated to a temperature lower than the melting point of the second sheet 2, or to a temperature 50°C lower than the melting point, and in this state, ultrasonic vibrations may be applied to the first and second sheets 1 and 2 sandwiched between the convex portions 35 of the concave-convex roll 31 and the vibration application surface 42t. Moreover, either the preheating means 51 or the horn heating means 61 may be used alone, or both may be used in combination.

[0094] From the viewpoint of more easily forming the through-holes 6 and the valve membrane body 20, it is preferable that the first sheet 1 and the second sheet 2 are each a spunbond nonwoven fabric or an air-through nonwoven fabric containing core-sheath type composite fibers as constituent fibers in the method for manufacturing the top sheet 10. It is preferable to use the core-sheath type composite fibers with a core of polyethylene terephthalate (PET) and a sheath of polyethylene (PE).

[0095] 16 to 19 show the main part (tip) of another embodiment of the ultrasonic horn according to the present invention. In the embodiments described below, the components that are different from the ultrasonic horn 42 described above will be mainly described, and the same components will be denoted by the same reference numerals and will not be described again. For components that are not specifically described, the description of the ultrasonic horn 42 will be applied as appropriate.

[0096] 16, in a cross-sectional view along the MD of the ultrasonic horn 42, the recess bottom surface 46b of the groove-shaped recess 46 is straight, and the groove-shaped recess 46 has a rectangular shape in the cross-sectional view. In other words, the recess bottom surface 46b of the ultrasonic horn 42A is flat. Even when ultrasonic horn 42A is used, the same effect as when ultrasonic horn 42 described above is basically achieved. However, from the viewpoint of more reliably suppressing the disadvantages that may arise from forming groove-shaped recess 46, such as a decrease in durability of ultrasonic horn 42 and the resulting occurrence of cracks, it is preferable that the cross-sectional shape of recess bottom surface 46b be an arc-shaped recess that is concave in the direction away from opening 46d, as shown in FIG. 14.

[0097] In the ultrasonic horn 42B shown in Figure 17, the vibration application surface 42t has an arc shape that is concave in the direction away from the rotation axis when viewed in a cross section along the direction (MD) perpendicular to the rotation axis of the uneven roll 31 (first roll). The vibration application surface 42t referred to here is assumed to be the surface when the groove-like recess 46 does not exist, and more specifically, when viewed in cross section along the MD as shown in Figure 17, the vibration application surface 42t is virtually extended from a corner 46c on one side of the MD to a corner 46c on the other side, sandwiching the opening 46d of the groove-like recess 46. Since the cross-sectional shape of the vibration application surface 42t along the MD is arc-shaped in this manner, the shear force applied to the fusion object (a laminate of the first sheet 1 and the second sheet 2) in the ultrasonic processing process is improved, and this, combined with the effect of the groove-shaped recess 46, makes it possible to more reliably form the fusion portion, the through hole 6, and the valve membrane body 20 simultaneously.

[0098] 17, in a cross-sectional view along MD, the arc-shaped vibration application surface 42t is preferably curved along a circular path (not shown) along which the tips of the convex portions 35 of the uneven roll 31 (first roll) pass. This lengthens the time during which the object to be fused (a laminate of the first sheet 1 and the second sheet 2) is sandwiched between the tip surfaces 35c of the convex portions 35 and the vibration application surface 42t, making it possible to more reliably form the fused portion, the through-hole 6, and the valve membrane body 20 simultaneously.

[0099] Furthermore, when the vibration application surface 42t of the ultrasonic horn 42 is arc-shaped in a cross-sectional view along the MD, it is preferable that the tip surface 35c of each of the multiple convex portions 35 of the corresponding uneven roll 31 is convex in a direction away from the rotation axis of the uneven roll 31 in the same cross-sectional view, and that the direction of curvature matches that of the vibration application surface 42t. The radius of curvature of the vibration application surface 42t of the ultrasonic horn 42B is preferably 100% or more of the radius of curvature of the tip surface 35c of the convex portion 35 of the concave-convex roll 31. The radius of curvature of the vibration application surface 42t is preferably 500% or less, and more preferably 200% or less.

[0100] In the ultrasonic horn 42B shown in FIG. 17, the vibration application surface 42t has an arc-shaped cross-sectional shape along the MD over the entire area in the direction parallel to the rotation axis of the uneven roll 31, but it may also have a portion with a different cross-sectional shape in a portion that does not face the convex portion 35 in the direction parallel to the rotation axis. For example, as shown in Figure 11, if a gap G is provided between adjacent gears that make up the uneven roll 31, a flat portion that does not protrude from the arc-shaped vibration application surface 42t may be provided at the portion of the vibration application surface 42t that faces the gap G.

[0101] In the ultrasonic horn 42C shown in Figure 18, the tip of the ultrasonic horn 42 includes a heat storage section 421 fixed to a metal main body 420 of the ultrasonic horn 42C, and the vibration application surface 42t is formed from the heat storage section 421. The groove-shaped recess 46 is formed at least in the heat storage portion 421 . In FIG. 18, the groove-shaped recess 46 is formed only in the heat storage portion 421, but it may extend to the main body portion 420 by penetrating the heat storage portion 421 in the thickness direction. Furthermore, the vibration application surface 42t formed by the heat storage section 421 shown in FIG. 18 has an arc shape in cross section along the MD, similar to the vibration application surface 42t of the ultrasonic horn 42B described above, but it may not have an arc shape and may be flat.

[0102] The heat storage section 421 is made of a heat storage material that has a lower thermal conductivity than the metal that constitutes the main body section 420 . The thermal conductivity of the heat storage material constituting the heat storage section 421 is preferably 2.0 W / mK or less, and more preferably 1.0 W / mK or less, from the viewpoint of making it difficult for heat to be dissipated to the ultrasonic horn or the atmosphere. The thermal conductivity of the heat storage material is preferably 0.1 W / mK or more, and more preferably 0.5 W / mK or more, from the viewpoint of efficiently heating the sheet. The thermal conductivity of the heat storage material can be measured by a conventional method using a thermal conductivity measuring device.

[0103] When the vibration application surface 42t is formed from the heat storage portion 421, the heat generated by the ultrasonic vibrations in the first and second sheets 1 and 2 is stored in the heat storage portion 421, and as a result, the temperature of the heat storage portion 421 rises, making it possible to heat the first sheet 1 and the second sheet 2. Therefore, in combination with the effect of the groove-like recess 46 formed in the vibration application surface 42t, the simultaneous formation of the fused portion, the through-hole 6, and the valve membrane body 20 can be carried out more reliably. Furthermore, when the vibration application surface 42t is formed from the heat storage section 421, the occurrence of inconveniences such as adhesion of molten resin to the conveying means caused by melting of the first and second sheets 1, 2 and wrapping of the sheets around the conveying roll is suppressed, which has the advantage of reducing the maintenance burden on the manufacturing equipment. The thickness Th (see FIG. 18) of the heat storage section 421 is not particularly limited, but from the viewpoint of ensuring that the heat storage section 421 exerts its effects more reliably, it is preferably 5 μm or more, and more preferably 10 μm or more. The thickness Th is preferably 100 μm or less, and more preferably 50 μm or less.

[0104] As the heat storage material constituting the heat storage section 421, it is preferable to use a synthetic resin that has excellent wear resistance and heat resistance, provided that the thermal conductivity is lower than that of the metal constituting the main body section 420. Examples of such synthetic resins include polyimide, polybenzimidazole, polyether ethyl ketone, polyphenylene sulfite, polyetherimide, polyamideimide, and other synthetic resins 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. As the heat storage material, synthetic resins such as polyimide and polybenzimidazole, which have a Rockwell hardness of R125 or more and R140 or less and a heat-resistant temperature of 280°C or more and 400°C or less, are particularly preferred. Here, the Rockwell hardness is a value measured in accordance with ASTM D-785, and the heat resistance temperature is a value measured in accordance with ASTM D-648.

[0105] There are no particular limitations on the means for fixing the synthetic resin heat storage section 421 to the metal main body section 420, and any known fixing means can be used. The heat storage section 421 made of synthetic resin can be formed on the main body section 420 made of metal by thermal spraying, for example, and fixed to the main body section 420. The term "thermal spraying" as used herein refers to a known surface treatment method in which particles of a spray material, such as a metal or ceramic, which has been heated to a molten or nearly molten state, are accelerated and collided at high speed with the surface of a substrate, thereby forming a coating on the surface of the substrate. As the spraying material, any material that can be sprayed and that can contribute to improving the fixing strength of the heat storage section 421 made of synthetic resin can be used without any particular restrictions, but from the viewpoint of excellent bonding strength to the main body section 420 made of metal such as titanium alloy, and excellent wear resistance and heat resistance, ceramics such as tungsten carbide, zirconia, chromium carbide, alloys such as aluminum magnesium, zinc aluminum, metals such as aluminum, stainless steel, titanium, molybdenum, and thermit, which is a composite material of metal and ceramic, are preferably used.

[0106] In an ultrasonic horn 42D shown in FIG. 19, a concave-convex portion 48 is formed in a groove-like recess non-forming portion 47 on a vibration application surface 42t. 19(a), a part of the groove-shaped recess-free portion 47 is an uneven portion 48, and the remaining part of the groove-shaped recess-free portion 47 is a smooth portion 49 that is smooth and has no unevenness. The uneven portion 48 has a larger surface roughness than the smooth portion 49, and therefore has a stronger frictional force. In the ultrasonic treatment process, a shear force acts on the portion of the fusion object (a laminate of the first sheet 1 and the second sheet 2) pressed by the uneven portion 48, which, combined with the effect of the groove-shaped recess 46, makes it possible to more reliably form the fusion portion, the through hole 6, and the valve membrane body 20 simultaneously.

[0107] 19(b), the uneven portion 48 has a plurality of convex portions 481 and a plurality of concave portions 482. The convex portions 481 are triangular in a cross section taken along the MD as shown in the figure, but the shape of the convex portions 481 in the cross section is not particularly limited, and may be, for example, a rectangle, a trapezoid, or the like. Furthermore, an example of an arrangement pattern of multiple convex portions 481 in the uneven portion 48 is an arrangement pattern in which a row of convex portions in which the convex portions 481 are arranged at equal intervals in the CD (direction along the rotation axis of the uneven roll 31) is arranged at equal intervals in the MD. Another example of the arrangement pattern is an arrangement pattern in which a row of convex portions, in which convex portions 481 are arranged at equal intervals in the CD, are arranged at equal intervals in the MD, and adjacent rows of convex portions in the MD are shifted by half a pitch. The uneven portion 48 can be formed by knurling or spraying the groove-like recess-free portion 47 on the vibration application surface 42t.

[0108] In the embodiment shown in Figure 19, a smooth portion 49 exists between the groove-shaped recess 46 and the uneven portion 48, but the smooth portion 49 may not exist between the groove-shaped recess 46 and the uneven portion 48, and the groove-shaped recess 46 and the uneven portion 48 may be adjacent to each other in the MD. Furthermore, the vibration application surface 42t may not have the smooth portion 49, and the entire groove-like recess non-forming portion 47 may be the uneven portion 48.

[0109] In order to ensure that the effects of the uneven portion 48 are achieved more reliably, the surface roughness of the uneven portion 48 is preferably 3.2 μm or more, and more preferably 6.3 μm or more, in terms of arithmetic mean roughness Ra. The surface roughness of the uneven portion 48 is preferably 12.5 μm or less, more preferably 25 μm or less, in terms of arithmetic mean roughness Ra. The arithmetic mean roughness Ra can be measured using various surface roughness measuring instruments, for example, a surface roughness measuring instrument manufactured by Mitutoyo Corporation.

[0110] From the same viewpoint, it is preferable to set the dimensions of the uneven portion 48 as follows. The ratio of the area (48S) of the uneven portion 48 to the area (47S) of the groove-like recess-free portion 47 of the vibration application surface 42t, that is, the ratio calculated by (48S / 47S)×100, is preferably 15% or more, and more preferably 30% or more. The ratio is preferably 100% or less, and more preferably 80% or less. The unit area (1 cm ) of the convex portion 481 constituting the concave-convex portion 48 2 The number of the per unit is preferably 1 or more, and more preferably 100 or more. Also, the unit area of ​​the convex part 481 (1 cm 2 The number per unit area is preferably 1,000,000 or less, and more preferably 10,000 or less. In a plan view of the uneven portion 48, the area of ​​one of the convex portions 481 is 0.0001 mm 2 More than 0.01 mm is preferable. 2 The above is more preferable. The area of ​​one of the convex portions 481 is 100 mm 2 Less than 1mm is preferable 2 The following is more preferred:

[0111] The present invention has been described above based on its preferred embodiments, but the present invention is not limited to the above embodiments and can be modified as appropriate within the scope of the invention. For example, although the topsheet 10 in the above-described embodiment has a laminated structure in which the first sheet 1 and the second sheet 2 are laminated, the topsheet 10 may have a single-layer structure. From the viewpoint of further improving the strength of the above-described protrusions 5 and further increasing resistance to the wearer's body pressure, it is preferable that the topsheet 10 has the above-described laminated structure. Although one groove-shaped recess 46 is formed on the vibration application surface 42t in the above embodiment, a plurality of groove-shaped recesses 46 may be formed. In this case, for example, a plurality of groove-shaped recesses 46 extending in the CD may be intermittently arranged in the MD, or a plurality of groove-shaped recesses 46 extending in the CD may be intermittently arranged in the CD. Furthermore, the configuration of one embodiment described above can be applied to other embodiments. For example, the vibration application surface 42t (see Figure 19) of the ultrasonic horn 42D on which the uneven portion 48 is formed may have an arc shape concave in a direction away from the rotation axis when viewed in a cross section (cross section along MD) perpendicular to the rotation axis of the uneven roll 31, as shown in Figure 17. Furthermore, when the vibration application surface 42t is formed from a heat storage portion 421 as shown in FIG. 18, the vibration application surface 42t made of the heat storage portion 421 may have an uneven portion 48 formed thereon.

[0112] In relation to the above-described embodiment of the present invention, the following topsheet for absorbent articles and absorbent articles including the same are further disclosed. <1> The valve membrane is made of a fibrous material, has a plurality of through holes, and is provided at a part of the open end of the through holes with a valve membrane body made of a film of the fibrous material, The valve membrane body is rotatable around a part of the open end of the through hole as an axis.

[0113] <2> When a load is applied to the valve body from the skin-facing surface side, the entire valve body is rotatable around a part of the opening end of the through hole as an axis. <1> The top sheet for absorbent articles according to claim 1. <3> The area of ​​the valve body is 5% to 50%, preferably 10% to 40%, of the area of ​​the through-hole. <1> or <2> The top sheet for absorbent articles according to claim 1. <4> The area of ​​the through hole is 1 mm 2 More than 10mm 2 Less than 2 mm, preferably 2 Over 8mm 2 The above-mentioned <1> ~ <3> 10. The top sheet for absorbent articles according to claim 1. <5> The area of ​​the valve body is 0.5 mm 2 More than 5mm 2 Less than 1 mm, preferably 2 Over 2.5mm 2 The above-mentioned <1> ~ <4> 10. The top sheet for absorbent articles according to claim 1. <6> a protrusion protruding from one surface of the absorbent article topsheet at a location adjacent to the through-hole, The valve membrane extends from the bottom of the protrusion toward the inside of the through hole. <1> ~ <5> 10. The top sheet for absorbent articles according to claim 1. <7> The laminated structure has a first sheet and a second sheet stacked together, and at least a part of the first sheet other than the through-hole forms the convex portion protruding toward the opposite side from the second sheet. <6> The top sheet for absorbent articles according to claim 1. <8> the valve body has a base edge portion located at a part of the open end, a free edge portion located opposite the base edge portion, and a pair of side edges located between the base edge portion and the free edge portion, The pair of side edges are not connected to the opening end. <1> ~ <7> 10. The top sheet for absorbent articles according to claim 1. <9> the percentage of the maximum length of the valve body in the extension direction relative 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; <8> The top sheet for absorbent articles according to claim 1. <10> The maximum length of the valve body in the extension direction is 1 mm or more and 5 mm or less, preferably 2 mm or more and 4 mm or less. <8> or <9> The top sheet for absorbent articles according to claim 1. <11> The length of the base edge portion is 1 mm or more and 10 mm or less, preferably 2 mm or more and 5 mm or less. <8> ~ <10> 10. The top sheet for absorbent articles according to claim 1.

[0114] <12> The free edge portion has a wavy shape in a plan view. <8> The top sheet for absorbent articles according to claim 1. <13> the ratio of the meandering length of the free edge to the length of the base edge is greater than 1 and less than 10, preferably greater than or equal to 2 and less than or equal to 5; <12> The top sheet for absorbent articles according to claim 1. <14> The minimum thickness of the valve body is 10 μm or more and 1 mm or less, preferably 20 μm or more and 500 μm or less. <1> ~ <13> 10. The top sheet for absorbent articles according to claim 1. <15> The valve membrane has a thick portion on the base end edge side located at a part of the opening end, the thick portion being thicker than other portions. <1> ~ <14> 10. The top sheet for absorbent articles according to claim 1. <16> the ratio of the minimum thickness of the valve 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; <15> The top sheet for absorbent articles according to claim 1. <17> 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. <15> or <16> The top sheet for absorbent articles according to claim 1. <18> The ratio of the number of the through holes formed with the valve membranes per unit area (10 mm x 10 mm) to the total number of the through holes per unit area in the top sheet for absorbent articles is 30% or more, preferably 50% or more, and more preferably the valve membranes are formed in all the through holes. <1> ~ <17> 10. The top sheet for absorbent articles according to claim 1. <19> The number of the through-holes in which the valve bodies are formed per unit area (10 mm x 10 mm) is 1 to 20, preferably 4 to 15. <1> ~ <18> 10. The top sheet for absorbent articles according to claim 1. <20> The aforementioned <1> ~ <19> An absorbent article comprising the top sheet for absorbent articles according to any one of the above items, The absorbent article top sheet is provided with a fiber sheet disposed on the non-skin facing side thereof and having a plurality of recesses and protrusions, The absorbent article, wherein the through-holes and the valve membrane of the topsheet for the absorbent article at least partially overlap with the recesses in the fiber sheet. <21> The depth of the recesses in the fiber sheet is 0.5 mm or more and 5 mm or less, preferably 1 mm or more and 3 mm or less. <20> The absorbent article according to claim 1. [Explanation of symbols]

[0115] 10 Surface sheet 1 Sheet 1 2. Second sheet 3 recess 5 Convex part 6 through holes 20 Valve 21 Proximal edge 22 Free edge 23 Side edge 25 Thick part 11 Absorbent articles (disposable diapers) 13 Back sheet 14 Absorbent 15 Sublayers 100 Surface sheet manufacturing equipment 30 Concave / convex shaping section 31 Concave and convex roll (first roll) 32 Uneven roll (second roll) 33 Engagement part 34 Suction hole 35 Convex part 35c Tip surface of convex part 36 Ultrasonic vibration application part 40 Ultrasonic processing unit 41 Ultrasonic fusion machine 42, 42A, 42B, 42C, 42D Ultrasonic Horn 420 Ultrasonic horn body 421 Heat storage section 42t Vibration application surface (tip surface of ultrasonic horn) 43 Converter 44 Booster 45 Movable platform 46 Groove-shaped recess 46a Recessed side 46b Bottom of recess 46c Corner 46d opening 47 Non-grooved recessed portion of vibration application surface 48 Uneven part 481 Convex 482 recess 49 Smooth section 50 Preheating mechanism 51 Preheating means 60 Horn heating mechanism 61 Horn heating means

Claims

1. A top sheet for absorbent articles made of a fibrous material and having a plurality of through holes, a valve membrane extending from a part of the opening end of the through hole toward the inside of the through hole and made of a film of a fiber material; The valve membrane body is rotatable in the thickness direction of the absorbent article topsheet around a base end edge portion connected to a part of the opening end as an axis.

2. 2. The topsheet for absorbent articles according to claim 1, wherein when a load is applied to the valve membrane partially from the skin-facing side, the entire valve membrane can rotate around a part of the open end of the through hole as an axis.

3. a protrusion protruding from one surface of the absorbent article topsheet at a location adjacent to the through-hole, The topsheet for absorbent articles according to claim 1 or 2, wherein the valve membrane extends from the bottom of the convex portion toward the inside of the through-hole.

4. 4. The top sheet for absorbent articles according to claim 3, having a laminated structure in which a first sheet and a second sheet are laminated, and at least a portion of the first sheet other than the through holes forms the convex portion protruding on the side opposite the second sheet side.

5. the valve body has the base edge portion, a free edge portion located opposite the base edge portion, and a pair of side edges located between the base edge portion and the free edge portion; The topsheet for absorbent articles according to any one of claims 1 to 4, wherein each of the pair of side edges is not connected to the opening edge.

6. The topsheet for absorbent articles according to claim 5, wherein the free edge portion has a wavy shape in a plan view.

7. 7. The topsheet for absorbent articles according to claim 1, wherein the valve membrane has a thick portion on the base edge side that is thicker than other portions.

8. An absorbent article comprising the top sheet for absorbent articles according to any one of claims 1 to 7, The absorbent article top sheet is provided with a fiber sheet disposed on the non-skin facing side thereof and having a plurality of recesses and protrusions, The absorbent article, wherein the through-holes and the valve membrane of the topsheet for the absorbent article at least partially overlap with the recesses in the fiber sheet.

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