Absorbent panty-type items

Abstract

To provide a pant-type absorbent article having the appearance of underwear. [Solution] The outer casing 10 has a laminated structure 13 in the ventral A and dorsal C portions, comprising an outer layer sheet 11 that forms the outer surface of the diaper 1, and an inner layer sheet 12 joined to the skin-facing surface 11a of the outer layer sheet 11 via a joint 14. The outer layer sheet 11 includes an expandable sheet 15 that is expandable in the transverse direction Y. Multiple joints 14 are intermittently arranged in both the longitudinal direction X and the transverse direction Y. When the diaper 1 is worn, the inner layer sheet 12 of the laminated structure 13 has a pleated structure 20 consisting of multiple recessed portions 21 extending in the longitudinal direction X with the joint 14 at the bottom, and hollow convex portions 22 located between the recessed portions 21. When the diaper 1 is worn, the pleated structure 20 can be seen through the outer layer sheet 11 when the diaper 1 is visually observed from the outside.

Description

[Technical Field]

[0001] This invention relates to a pant-type absorbent article having the appearance of underwear. [Background technology]

[0002] Pant-type absorbent articles, such as pant-type diapers, typically consist of an outer covering including a sheet such as nonwoven fabric, and an absorbent material positioned in the outer covering corresponding to the wearer's crotch area, as described in, for example, Patent Documents 1 to 3. The outer covering is shaped like pants and forms the outer surface of the diaper, and the appearance and feel of the diaper largely depend on the outer covering.

[0003] In recent years, there has been a demand for absorbent pant-type products that have an appearance and feel similar to regular underwear. To meet this demand, the pant-type diaper described in Patent Document 1 employs a laminated structure as the outer body, consisting of an outer layer sheet that forms the outer surface of the diaper and an inner layer sheet of a different color from the outer layer sheet, and the two sheets are joined by multiple joints intermittently arranged in the vertical and horizontal directions. As a result, in the natural state of the pant-type diaper described in Patent Document 1, the inner layer sheet has a pleated structure consisting of multiple recessed parts extending vertically with the joints at the bottom and hollow convex parts located between the recessed parts. When the pant-type diaper described in Patent Document 1 is observed from the outside, the pleated structure is almost invisible, and the shadows in the parts corresponding to the recessed parts are more prominent, resulting in the visible state in which shadows are regularly formed on the outer body. Furthermore, the regular shading on this outer surface is perceived by the viewer as being similar to the shading created by the regular structure seen in woven or knitted fabrics, thus enhancing the overall underwear-like appearance of the diaper. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2021-104287 [Patent Document 2] Japanese Patent Publication No. 2015-198915 [Patent Document 3] International Publication No. 2008 / 066006 [Overview of the project] [Problems that the invention aims to solve]

[0005] Although the pant-type diaper described in Patent Document 1 has an appearance similar to underwear, the level of underwear-likeness required for disposable diapers has increased in recent years, and there was room for improvement in terms of underwear-likeness.

[0006] The object of the present invention is to provide a pant-type absorbent article having the appearance of underwear. [Means for solving the problem]

[0007] Based on the pant-type diaper described in Patent Document 1, the inventors pursued the idea of ​​the diaper being more like underwear and found that the aforementioned problem can be solved by making the pleated structure of the inner layer sheet visible through the outer layer sheet.

[0008] The present invention is based on the above findings and is a pant-type absorbent article having a longitudinal direction extending from the wearer's abdominal side through the crotch to the back and a transverse direction perpendicular to the longitudinal direction, and being divided into an inseam section located in the crotch, an abdominal section located on the wearer's abdominal side of the inseam, and a dorsal section located on the wearer's back side of the inseam, and an outer casing located on the non-skin-facing side of the absorbent, and the two side edges of the outer casing along the longitudinal direction in the front and back panels are joined together to form a pair of side seals, a waist opening, and a pair of leg openings. In one embodiment of the pant-type absorbent article of the present invention, the outer casing has a laminated structure in the ventral and dorsal portions of an outer layer sheet forming the outer surface of the pant-type absorbent article and an inner layer sheet joined to the skin-facing surface of the outer layer sheet via a joint. In one embodiment of the pant-type absorbent article of the present invention, the outer layer sheet includes the stretchable sheet having elasticity in the transverse direction. In one embodiment of the pant-type absorbent article of the present invention, the joints are intermittently arranged in multiple locations in both the vertical and horizontal directions. In one embodiment of the absorbent pant-type article of the present invention, when the absorbent pant-type article is worn, the inner layer sheet of the laminated structure has a pleated structure consisting of a plurality of recessed portions extending in the longitudinal direction with the joint portion at the bottom, and hollow convex portions located between the recessed portions. In one embodiment of the absorbent pant-type article of the present invention, when the absorbent pant-type article is worn, the pleated structure can be confirmed through the outer layer sheet when the absorbent pant-type article is visually observed from the outside. [Effects of the Invention]

[0009] According to the present invention, a pant-type absorbent article having the appearance of underwear is provided. [Brief explanation of the drawing]

[0010] [Figure 1] Figure 1 is a schematic perspective view showing an example of a pant-type disposable diaper, which is one embodiment of the pant-type absorbent article of the present invention. [Figure 2] Figure 2 is a schematic unfolded plan view showing the skin-facing side (inner layer sheet side) of the diaper shown in Figure 1 in its unfolded and fully extended state. [Figure 3] Figure 3 is a schematic cross-sectional view showing the natural state of the diaper shown in Figure 1, specifically the section along line II in Figure 2 (a cross-section along the transverse and thickness directions of the disposable diaper). [Figure 4] Figure 4 is a schematic exploded perspective view of the diaper shown in Figure 1. [Figure 5] Figure 5 is a schematic longitudinal cross-sectional view showing the section along line II-II in Figure 2 (a section along the longitudinal and thickness directions of a disposable diaper). [Figure 6] Figure 6 is a schematic perspective view of the skin-facing side of the outer layer sheet (stretchable sheet) of the diaper shown in Figure 1. [Figure 7] FIG. 7(a) is a plan view schematically showing a pattern of a joint portion between an outer layer sheet and an inner layer sheet in the laminated structure of the diaper outer wrapper shown in FIG. 1, and FIG. 7(b) is a cross-sectional view schematically showing a cross-section along the lateral direction in the natural state of the laminated structure. [Figure 8] FIG. 8(a) is a schematic perspective view of the back side in the worn state of the diaper shown in FIG. 1, and FIG. 8(b) is a plan view schematically showing a part of the outer surface of the diaper shown in FIG. 8(a) in an enlarged manner. [Figure 9] FIG. 9 is a schematic front view of the ilium. [Figure 10] FIG. 10 is a view corresponding to FIG. 5 of another embodiment of the pant-type absorbent article of the present invention.

BEST MODE FOR CARRYING OUT THE INVENTION

[0011] Hereinafter, the present invention will be described based on its preferred embodiments with reference to the drawings. In the description of the following drawings, the same or similar parts are denoted by the same or similar reference numerals. The drawings are basically schematic, and the ratios of each dimension etc. may be different from the actual ones.

[0012] In FIGS. 1 to 8, a pant-type disposable diaper 1 or a part thereof, which is an embodiment of the pant-type absorbent article of the present invention, is shown. The diaper 1 has a longitudinal direction X extending from the ventral side of the wearer through the crotch to the dorsal side and a lateral direction Y orthogonal to the longitudinal direction X, and has an absorber 5 for absorbing and holding body fluids such as urine, and an outer wrapper 10 disposed on the non-skin-facing surface side of the absorber 5. And both side edge portions along the longitudinal direction X of the outer wrapper 10 in the front body portion F and the back body portion R are joined to form a pair of side seal portions S, S, a waist opening WH, and a pair of leg openings LH, LH.

[0013] As shown in Figure 2, the front panel F is the part that covers the ventral side (front side) of the wearer's body when worn, based on the vertical center line CLx that bisects the diaper 1 in the vertical direction X and extends in the horizontal direction Y, and the back panel R is the part that covers the dorsal side (back side) of the wearer's body. In this specification, the "skin-facing side" is the side of the absorbent article or its components (e.g., outer casing) that faces the wearer's skin 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" is the side of the absorbent article or its components that faces away from the skin when the absorbent article is worn, i.e., the side that is relatively farther from the wearer's skin. Here, "when worn" means the normal and proper wearing position, i.e., the state in which the correct wearing position of the absorbent article is maintained.

[0014] As shown in Figure 2, the diaper 1 of this embodiment is divided into an abdominal portion A, which is located on the wearer's abdominal side when worn, a dorsal portion C, which is located on the wearer's back side, and a crotch portion B, which is located between them and is positioned in the wearer's crotch area. The abdominal portion A is part of the front body F, and the dorsal portion C is part of the back body R. The crotch portion B straddles the vertical center line CLx in the vertical direction X and exists from the front body F to the back body R. Both the abdominal portion A and the dorsal portion C have a portion that is in the same position as the side seal portion S in the vertical direction X, that is, a portion sandwiched between a virtual straight line extending in the horizontal direction Y through the vertical outer end Sa of each of the pair of side seal portions S, S and a virtual straight line extending in the horizontal direction Y through the vertical inner end Sb of each of the pair of side seal portions S, S. The crotch portion B is a region in which leg edge portions LS, LS, which are recessed portions for forming leg openings LH, LH, are formed on both side edges of the outer body 10 along the vertical direction X. The ventral portion A, the crotch portion B, and the dorsal portion C are the regions obtained by dividing the diaper 1, in its unfolded and fully extended state as shown in Figure 2, into three equal parts along its longitudinal direction X.

[0015] In this specification, "unfolded and fully extended state" means the state in which the diaper 1 is separated at the side seal portion S to be unfolded, and the diaper 1 in the unfolded state is expanded to the design dimensions, that is, the dimensions when it is spread out in a flat plane with all influence of the elastic members completely eliminated, by fully extending the elastic members of each part.

[0016] The diaper 1 of this embodiment has an absorbent body 2 including an absorbent material 5, and the outer casing 10 is positioned on the non-skin-facing side of the absorbent body 2. The absorbent body 2 has a rectangular shape in plan view, as shown by the outline in Figure 2, and its longitudinal direction coincides with the vertical direction X of the diaper 1 when unfolded and in its maximum extended state. It is positioned in the center of the outer casing 10 in the horizontal direction Y and is joined to the outer casing 10 with adhesive. The outer casing 10 forms the outline of the diaper 1 and, when unfolded and in its maximum extended state as shown in Figure 2, has an hourglass shape with a constriction in the center in the vertical direction X.

[0017] As shown in Figure 3, the absorbent body 2 has a liquid-permeable surface sheet 3 that forms the skin-facing surface, a liquid-impermeable, liquid-difficult-permeable, or water-repellent back sheet 4 that forms the non-skin-facing surface, and an absorbent body 5 interposed between the two sheets 3 and 4. The absorbent body 5 has an absorbent core 50 capable of absorbing and retaining bodily fluids, and a core wrap sheet 51 that covers the outer surface of the absorbent core 50. These components constituting the absorbent body 2 are joined together by known joining means such as adhesives.

[0018] The components of the absorbent body 2 can be any of the various materials conventionally used in this type of absorbent article, without any particular limitations. For the surface sheet 3, for example, various nonwoven fabrics and perforated films can be used. For the back sheet 4, for example, a resin film, a laminate of a resin film and a nonwoven fabric, etc. can be used. The absorbent core 50 is typically mainly composed of a water-absorbing material, and the water-absorbing material contains one or more selected from fibrous materials such as wood pulp and water-absorbing polymers. The core wrap sheet 51 is typically made of paper, nonwoven fabric, etc. The core wrap sheet 51 is optional.

[0019] A pair of leak-proof cuffs 6, 6 are provided on both sides of the skin-facing surface of the absorbent body 2 (surface sheet 3) along the longitudinal direction X. Each leak-proof cuff 6 includes a liquid-impermeable and breathable cuff sheet 60. One end of the cuff sheet 60 in the transverse direction Y is fixed to another member (the core wrap sheet 51 and inner layer sheet 12 in the configuration shown in Figure 3) and serves as a fixed end, while the other end of the cuff sheet 60 in the transverse direction Y is a free end not fixed to another member. An elastic cuff member 61 is positioned at the free end of the cuff sheet 60 so as to be expandable and contractible in the longitudinal direction X by being fixed in an extended state in that direction. When diaper 1 is worn, the contraction force of the elastic member 61 causes the free end side of the cuff sheet 60 to stand up towards the wearer, at least in the crotch area B, with the fixed end as the base for standing upright, thereby causing the pair of leak-proof cuffs 6, 6 to stand upright, which prevents urine and other excrement from flowing outward in the lateral direction Y.

[0020] A cover sheet 7 is placed on the ventral A and dorsal C portions to cover the skin-facing surface of the longitudinal X end of the absorbent body 2. As shown in Figures 2 and 4, the cover sheet 7 straddles the longitudinal X end of the absorbent body 2 in either the ventral A or dorsal C portion and extends along the entire length of the diaper 1 (outer body 10) in the transverse Y direction. The cover sheet 7 serves to prevent the shedding of absorbent materials such as superabsorbent polymers from the absorbent body 5 and to absorb bodily fluids such as sweat from the wearer, and is made of a liquid-permeable sheet such as nonwoven fabric or paper.

[0021] As shown in Figures 3 and 4, the outer casing 10 has a laminated structure 13 in the ventral A and dorsal C portions, consisting of an outer layer sheet 11 that forms the outer surface of the diaper 1 and an inner layer sheet 12 joined to the skin-facing surface of the outer layer sheet 11 via a joint 14. When the diaper 1 is worn, the outer layer sheet 11 is positioned on the side furthest from the wearer's skin, and the inner layer sheet 12 is positioned on the side closer to the wearer's skin.

[0022] In this embodiment, as shown in Figure 4, the outer layer sheet 11 is composed of a ventral outer layer sheet 110 that constitutes the ventral part A and a dorsal outer layer sheet 111 that constitutes the dorsal part C, and includes multiple sheets 110, 111. Unless otherwise specified, the term "outer layer sheet 11" includes the ventral outer layer sheet 110 and the dorsal outer layer sheet 111. The ventral outer layer sheet 110 is arranged over the entire area of ​​the ventral part A and in the area of ​​the crotch B closer to the ventral part A. The dorsal outer layer sheet 111 is arranged over the entire area of ​​the dorsal part C and in the area of ​​the crotch B closer to the dorsal part C. There is an area in the center of the crotch B in the vertical direction X where the outer layer sheet 11 is not placed. On the other hand, the inner layer sheet 12 is arranged over the entire area of ​​the diaper 1 and forms the outline of the outer casing 10. Therefore, in this embodiment, the laminated structure 13 is arranged at least in the ventral portion A and the dorsal portion C, and is not arranged in the central portion of the crotch area B in the longitudinal direction X (the portion where the outer layer sheet 11 is not arranged). In the portion of the outer casing 10 where only the inner layer sheet 12 is arranged, the inner layer sheet 12 forms the outer surface of the diaper 1.

[0023] In this embodiment, as shown in Figures 2, 4, and 5, the outer layer sheet 11 and the inner layer sheet 12 each have their outer edges in the vertical direction X folded back towards the skin-facing side along a fold line (not shown) extending in the horizontal direction Y. Specifically, the ventral outer layer sheet 110 and the dorsal outer layer sheet 111 each have a folded portion 11E at their outer edges in the vertical direction X that is folded back towards the skin-facing side, and the inner layer sheet 12 has a folded portion 12E at its outer edge in the vertical direction X that is folded back towards the skin-facing side. The fold line in the outer layer sheet 11 is located at the vertical edge 1X of the diaper 1. The folded portion 12E is longer in the vertical direction X than the folded portion 11E, and starting from the vertical edge 1X side of the diaper 1, it has a portion where the skin-facing side is covered by the folded portion 11E and a portion where the skin-facing side is exposed. The folded portions 11E and 12E are each joined to other opposing members by a joining means. The joining means is not particularly limited and includes, for example, adhesives and fusion bonding.

[0024] In this embodiment, as shown in Figures 2 and 5, the outer garment 10 includes, at least in the back body R, the opening edge of the waist opening WH, an elastic member 8 for forming waist gathers, and has a waist region 10A located at the outermost edge in the vertical direction X, a torso region 10B adjacent to the waist region 10A, and a crotch adjacent region 10C adjacent to the torso region 10B. The boundary between the torso region 10B and the crotch adjacent region 10C is a virtual straight line (not shown) extending in the lateral direction Y through one vertical inward end Sb of a pair of side seal portions S,S and the other vertical inward end Sb.

[0025] The waist region 10A and the torso region 10B are located in the same position as the side seal portion S in the longitudinal direction X of the outer body 10, that is, in the portion between a virtual straight line extending in the transverse direction Y through the longitudinal outer end Sa of each of the pair of side seal portions S, S and a virtual straight line extending in the transverse direction Y through the longitudinal inner end Sb of each of the pair of side seal portions S, S. Both regions 10A and 10B are typically located in the ventral A and dorsal C portions, and are not located in the crotch area B.

[0026] The waist region 10A may be a region within 40 mm inward in the vertical direction X from the vertical end 1X of the diaper 1 in the unfolded and fully extended state shown in Figure 2. Alternatively, in the unfolded and fully extended state shown in Figure 2, the ratio of the length of the waist region 10A in the same direction to the total length of the side seal portion S in the vertical direction X is preferably 10% or more, more preferably 15% or more, preferably 40% or less, and more preferably 35% or less.

[0027] The crotch area adjacent region 10C may be an area within 120 mm inward in the vertical direction X from a virtual straight line extending in the horizontal direction Y through the vertical inward ends Sb of each of the pair of side seal portions S, S. The crotch area adjacent region 10C exists continuously from the virtual straight line to the inward end in the vertical direction X of the outer casing 10.

[0028] In this embodiment, as shown in Figure 2, the position of the inner end of the ventral part A in the longitudinal direction X coincides with the position of the inner end of the ventral outer layer sheet 110 in the longitudinal direction X. Also in this embodiment, as shown in Figure 4, the length of the dorsal outer layer sheet 111 is longer in the longitudinal direction X than the ventral outer layer sheet 110, and therefore, as shown in Figure 2, the length of the crotch adjacent region 10C is longer in the longitudinal direction X of the back body R than of the front body F. For this reason, the crotch adjacent region 10C is present only in the ventral part A of the front body F and not in the crotch B, but in the back body R it is present from the dorsal part C to a part of the crotch B. The crotch adjacent region 10C of the back body R corresponds to the buttocks of the wearer of the diaper 1.

[0029] In this embodiment, a plurality of elastic members 8 for forming waist gathers are arranged in the waist region 10A of the outer body 10 so as to be expandable and contractible in the lateral direction Y. Each of the plurality of elastic members 8 for forming waist gathers is thread-like, extends in the lateral direction Y, and is intermittently arranged in the vertical direction X. The plurality of elastic members 8 for forming waist gathers are positioned in an extended state in the lateral direction Y between the folded portion 12E of the inner layer sheet 12 and the non-folded portion of the inner layer sheet 12 opposite to it, and are fixed with adhesive. In the natural state of the diaper 1, waist gathers are formed in the waist region 10A (the opening edge of the waist opening WH) by the contraction of the elastic members 8 for forming waist gathers.

[0030] In this specification, "natural state" refers to a state in which no external force is applied to the elastic components of the object (e.g., a diaper).

[0031] In this embodiment, multiple thread-like elastic members 9 for forming leg gathers are arranged to stretch and contract along the leg edge LS of the outer body 10 of the front body F. On the other hand, no elastic members 9 are arranged on the back body R. On the front body F, the multiple elastic members 9 for forming leg gathers are arranged in an extended state on the skin-facing surface of the inner layer sheet 12 and fixed with adhesive. In the natural state of the diaper 1, the contraction of the elastic members 9 for forming leg gathers forms leg gathers at the opening edge of the leg opening LH on the ventral side A. In addition to the outer body 10, a sheet for fixing the elastic members 9 for forming leg gathers may be provided. For example, an elastic member cover sheet (not shown) may be provided to cover the elastic members 9 for forming leg gathers that are arranged on the skin-facing surface of the inner layer sheet 12.

[0032] The outer layer sheet 11 includes an expandable sheet 15 that is expandable in the lateral direction Y, thereby providing expandability in the lateral direction Y. In this specification, "expandable sheet" refers to a sheet that is inherently expandable, and is different from an expandable sheet (hereinafter also referred to as an "elastic member fixed expandable sheet") which is formed by fixing a separate elastic member in an extended state to the surface of a sheet that is not expandable (non-expandable sheet). The outer layer sheet 11 is assumed to be expandable in the lateral direction Y, and in addition to the expandable sheet 15, it may also include other sheets, and these other sheets may not be expandable in the lateral direction Y.

[0033] In this embodiment, the outer layer sheet 11 (ventral outer layer sheet 110 and dorsal outer layer sheet 111) is made of a stretchable sheet 15. As shown in Figure 6, the outer layer sheet 11 made of the stretchable sheet 15 has a base sheet 16 and a plurality of elastic filaments 17 arranged on one side of the base sheet 16 so as to be stretchable in the transverse direction Y. The plurality of elastic filaments 17 extend in the transverse direction Y and are intermittently arranged in the longitudinal direction X. The surface on which the elastic filaments 17 are arranged on the base sheet 16 is the skin-facing surface 11a of the outer layer sheet 11, except for the folded portion 11E, and is positioned opposite to other members such as the inner layer sheet 12. Also, the surface on which the elastic filaments 17 are not arranged on the base sheet 16 is the non-skin-facing surface 11b of the outer layer sheet 11, except for the folded portion 11E, and forms the outer surface of the diaper 1. The opposite is true for the folded portion 11E (see Figure 5).

[0034] Each of the multiple elastic filaments 17 is joined to the base sheet 16 by fusion. That is, the joining of the elastic filaments 17 and the base sheet 16 is not done via other components such as adhesives, but by melting at least one of the resins constituting the elastic filaments 17 and the resins constituting the base sheet 16. From the viewpoint of the joint strength between the elastic filaments 17 and the base sheet 16, it is preferable that the elastic filaments 17 are joined to the base sheet 16 by continuous fusion along their entire length.

[0035] The elastic filament 17 is joined to the base sheet 16 in a non-stretched state. Here, "non-stretched state" means a state in which it does not contract any further when the external force is removed. In contrast, in an elastic member-fixed type expandable sheet, the thread-like elastic member is joined to the base sheet in an stretched state.

[0036] The elastic filament 17 is made from, for example, a thermoplastic elastomer or rubber. In particular, when a thermoplastic elastomer is used as the raw material, melt spinning using an extruder is possible, similar to ordinary thermoplastic resins, and the elastic filament 17 obtained in this way is easily heat-fused to the base sheet 16, making it suitable for the stretchable sheet 15. Examples of the thermoplastic elastomer include styrene-based elastomers such as SBS (styrene-butadiene-styrene), SIS (styrene-isoprene-styrene), SEBS (styrene-ethylene-butadiene-styrene), and SEPS (styrene-ethylene-propylene-styrene), olefin-based elastomers (ethylene-based α-olefin elastomers, propylene-based elastomers copolymerized with ethylene-butene-octene, etc.), polyester-based elastomers, polyurethane-based elastomers, etc., and one of these can be used alone or in combination of two or more.

[0037] The base sheet 16 has stretchability that allows it to be stretched in the direction of extension of the elastic filament 17 (lateral direction Y). Here, "having stretchability" includes (i) cases where the constituent fibers of the base sheet 16 themselves are stretched, and (ii) cases where, even if the constituent fibers themselves are not stretched, the base sheet 16 as a whole is stretched due to the separation of fibers that were bonded at intersections, the structural change of the three-dimensional structure formed by multiple fibers due to bonding between fibers, etc., the tearing of constituent fibers, or the stretching of the slack in the fibers. The base sheet 16 may already have stretchability in its raw state before being joined with the elastic filament 17, or it may not have stretchability in its raw state before being joined with the elastic filament 17, but may become stretchable after being processed to impart stretchability after being joined with the elastic filament 17. Specific examples of the processing include heat treatment, roll stretching, meshing stretching with tooth grooves or gears, and tensile stretching with a tenter.

[0038] With regard to the "stretchable" aspect mentioned above, from the viewpoint of ensuring that the predetermined effects of the present invention are achieved more reliably, it is preferable that the base sheet 16 has a transverse Y elongation rate (length change) of 30% or more, and more preferably 100% or more and 300% or less, as measured by the measurement method A below.

[0039] <Method for measuring elongation rate A> After removing the elastic filaments 17 from the stretchable sheet 15 to be measured, leaving only the base sheet 16, a rectangle with a length of 2 cm in the transverse direction Y (the direction in which the elastic filaments 17 extend) and a length of 1 cm in the longitudinal direction X is cut out from the base sheet 16 to be used as a test specimen. Two marks are made in the center of the surface of the test specimen, with a distance of 1 cm between the two marks in the longitudinal direction of the specimen. The marks can be made with an oil-based pen or the like. Next, the chuck distance of a tensile testing machine (for example, the Tensilon tensile testing machine "RTM100" manufactured by Orientec Co., Ltd.) is set to 1 cm, and the test specimen is fixed between the chucks so that the longitudinal direction of the test specimen coincides with the tensile direction. The chuck distance is increased at a tensile speed of 100 mm / min to stretch the test specimen longitudinally to a load of 50 g, and then the length of the test specimen is measured. The elongation rate is calculated using the following formula. Elongation rate (%) = [{Length of specimen after stretching (mm) - Length of specimen before stretching (mm)} / Length of specimen before stretching (mm)] × 100

[0040] In the measurement method A described above, one example of a method for removing the elastic filaments 17 from the stretchable sheet 15 is to use an organic solvent in which the base sheet 16 is insoluble and the elastic filaments 17 are soluble. Specifically, this method involves immersing the stretchable sheet 15 in the organic solvent to dissolve only the elastic filaments 17 in the organic solvent, and then drying the base sheet 16. For example, if the elastic filaments 17 are made of a styrene-based block copolymer of thermoplastic elastomer and the base sheet 16 is made of polypropylene, toluene can be used as the organic solvent.

[0041] As the base sheet 16, nonwoven fabrics manufactured by various methods can be used, for example, air-through nonwoven fabrics, heat-rolled nonwoven fabrics, spunlace nonwoven fabrics, spunbond nonwoven fabrics, and meltblown nonwoven fabrics.

[0042] The stretchable sheet 15 is typically manufactured by a process (fusion process) in which multiple molten or softened elastic filaments 17 spun from multiple spinning nozzles are brought into contact with one surface of a base sheet 16 before the elastic filaments 17 solidify, thereby obtaining a composite sheet in which the elastic filaments 17 are fused to the base sheet 16. Preferably, after the fusion process, a process (stretchability imparting process) is carried out to impart stretchability to the composite sheet. The stretchability imparting process is a process of stretching the composite sheet in the direction in which the elastic filaments 17 extend, thereby imparting stretchability to the base sheet 16, which does not inherently have stretchability.

[0043] As the stretchable sheet constituting the outer layer sheet according to the present invention, the stretchable sheet described in Japanese Patent Publication No. 7481817 can be used.

[0044] The inner layer sheet 12 is typically non-stretchable and non-elastic. "Non-stretchable" here means that the elongation rate (length change) is less than 30%. "Non-elastic" here means that the elongation recovery rate at 100% elongation, as measured by the method described below, is 20% or less, or that it breaks before reaching 100% elongation. The non-elastic inner layer sheet 12 preferably has a maximum elongation of 90% or less.

[0045] <Method for measuring elongation recovery rate> Prepare a rectangular specimen from the sheet to be measured, measuring 50 mm in length and 25 mm in width. The specimen is fixed between the chucks (chuck spacing K0) of a tensile testing machine (for example, the Tensilon tensile testing machine "RTC-1150A" manufactured by Orientec Co., Ltd.) so that its longitudinal direction aligns with the tensile direction. The specimen is stretched by expanding the chuck spacing at a tensile speed of 300 mm / min until it reaches its 100% elongation length K2 (= K0 × 2). Then, the chuck spacing is narrowed at the same speed as the tensile speed until the tensile stress becomes 0. This length is defined as the length after elongation recovery, K1. The elongation recovery rate of the sheet to be measured is calculated using the following formula: Elongation recovery rate (%) = [(K2 - K1) / (K2 - K0)] × 100

[0046] As the inner layer sheet 12, nonwoven fabrics manufactured by various methods can be used, for example, the same material as the base sheet 16 can be used. The inner layer sheet 12 and the base sheet 16 may be of the same type or different types. Here, "same type of sheet" means sheets in which the manufacturing process, the type of constituent fibers, the fiber diameter and length of the constituent fibers, the thickness and basis weight of the sheet are all the same. If at least one of these is different, they are considered "different types of sheets".

[0047] In the laminated structure 13 of the exterior body 10, the outer layer sheet 11 and the inner layer sheet 12 are joined via joints 14. As shown in Figure 7(a), multiple joints 14 are intermittently arranged in both the vertical X and horizontal Y directions. In the configuration shown in Figure 7(a), multiple joint rows 14L, each consisting of multiple joints 14 intermittently arranged in a single row in the vertical X direction, are intermittently arranged in multiple locations in the horizontal Y direction. The joint rows 14L, which are the areas where joints 4 are located, and the areas 14M where no joints are located are alternately arranged in the horizontal Y direction.

[0048] In the configuration shown in Figure 7(a), the plan view shape of the joint 14 is circular, but the plan view shape of the joint 14 is not particularly limited and could be, for example, elliptical, triangular, or quadrilateral.

[0049] The joining method between the outer sheet 11 and the inner sheet 12 at the joint 14 is not particularly limited. Examples include fusion by melting the constituent fibers of both sheets 11 and 12, and bonding with an adhesive. They may also be joined by both fusion and bonding. The fusion of both sheets 11 and 12 can be carried out, for example, by embossing with heat, ultrasonic sealing, etc.

[0050] The laminated structure 13 is obtained by stretching an outer layer sheet 11, which includes an expandable sheet 15, in the transverse direction Y, which is the direction in which the elastic filaments 17 extend, then laminating an unstretched inner layer sheet 12 on the elastic filament 17 side of the stretched outer layer sheet 11, and finally forming a joint 14. The outer layer sheet 11 and the inner layer sheet 12 are not joined in any part other than the joint 14. Therefore, after forming the joint 14, when the stretching of the outer layer sheet 11 is released and the laminated structure 13 is returned to its natural state, the laminated structure 13 contracts in the transverse direction Y. In such a natural state of the laminated structure 13, as shown in Figure 7, in the region that overlaps with the joint row 14L in a plan view, the inner layer sheet 12 does not protrude and a recessed portion 21 is formed, and in the region that overlaps with the region without joints 14M in a plan view, the inner layer sheet 12 protrudes in a direction away from the outer layer sheet 11, forming a convex portion 22. A hollow portion 22A is formed between the outer sheet 11 and the inner sheet 12 in the raised ridge portion 22. Such an uneven structure is not substantially formed on the outer sheet 11.

[0051] When diaper 1 is worn, an external force acts on the laminated structure 13, so the external shape of the laminated structure 13 when diaper 1 is worn differs from that of the laminated structure 13 in its natural state. However, both have in common the formation of recessed portions 21 and convex portions 22 on the inner layer sheet 12. That is, when diaper 1 is worn, as shown in Figure 7(b), the inner layer sheet 12 of the laminated structure 13 has a pleated structure 20 consisting of a plurality of recessed portions 21 extending in the vertical direction X with a joint portion 14 at the bottom, and hollow convex portions 22 located between the recessed portions 21. Furthermore, in the laminated structure 13, the plurality of joint portions 14 are intermittently arranged in the horizontal direction Y, so the recessed portions 21 and convex portions 22 are easily formed alternately and regularly in the horizontal direction Y, making it easy to obtain a pleated structure 20 with a good appearance. Furthermore, in the laminated structure 13, multiple joints 14 are intermittently arranged in the vertical direction X, resulting in a better texture and feel against the skin of the pleated structure 20 compared to the case where the joints 14 are in a continuous straight line extending in the vertical direction X.

[0052] As shown in Figure 8, diaper 1 is characterized in that, when diaper 1 is observed visually from the outside while being worn, the pleated structure 20 can be confirmed through the outer layer sheet 11. The concave portion 21 is a peak with its highest point being the contact point with the outer sheet 11, and the convex portion 22 is a valley with its lowest point located away from the outer sheet 11. Furthermore, when observing in this manner, light is incident from the side of the outer sheet 11, so a shadow is cast on the convex portion 22, which is relatively farther from the outer sheet 11, by the sloping portion connecting the peak of the concave portion 21 and the lowest point of the convex portion 22, which is relatively closer to the outer sheet 11. Due to the influence of this shadow, the color tone of the convex portion 22 on the inner sheet 12 appears darker than that of the surrounding area. In reality, since the outer sheet 11 overlaps the non-skin-facing side of the inner sheet 12, when the diaper 1 is observed from the outside, this darker colored convex portion 22 is visible through the outer sheet 11. That is, when the outer surface of the diaper 1 is visually observed, areas with the same hue but different color tones are visible on the outer body 10. In this region, areas that appear relatively lighter in color extending in the vertical direction X (corresponding to the recessed areas 21) and areas that appear relatively darker in color extending in the vertical direction X (corresponding to the raised areas 22) are alternately arranged in the horizontal direction Y. In diaper 1, a substantially flat outer layer sheet 11 is superimposed on the outer surface of the inner layer sheet 12 that forms the pleat structure 20, and the pleat structure 20 is made visible through the outer layer sheet 11. When diaper 1 is worn, the pleat structure 20 can be seen through the outer layer sheet 11 when the diaper 1 is observed from the outside. The pleat structure 20 visible in this outer layer 10 is perceived by the viewer as a regular structure found in woven or knitted fabrics, thus improving the overall underwear-like appearance of diaper 1.

[0053] The pleat structure 20 is visible in environments where there is sufficient brightness, such as when the indoor lights are on or sunlight is entering. In environments where the diaper 1 is normally put on, the person wearing the diaper 1 or the person assisting them in putting it on can confirm the pleat structure 20 of the diaper 1.

[0054] Thus, diaper 1 has the characteristic that the pleated structure 20 of the inner layer sheet 12 can be seen through the outer layer sheet 11 when worn, and this makes it look like underwear when worn. In contrast, as mentioned above, the diaper described in Patent Document 1 does not allow the pleated structure of the inner layer sheet to be seen through the outer layer sheet, and instead, the shading in the parts corresponding to the recessed parts of the inner layer sheet is regularly formed on the outer body, and this is said to improve the overall underwear-like appearance of the diaper. While the diaper described in Patent Document 1 does have an appearance like underwear, the pant-type absorbent article of the present invention, represented by diaper 1, has an even greater underwear-like appearance. This will become clear from the comparison between Example 1 and Reference Example 1 described later.

[0055] According to the inventor's findings, in order for a diaper to look like underwear, it is important that it satisfies all of the following conditions 1) to 3): Condition 1) It looks like underwear when not worn. Condition 2) It looks like underwear when worn. Condition 3) When clothing is worn over the diaper and the clothing is observed from the outside, it looks like underwear is being worn. Regarding condition 3), in order to satisfy this, if the diaper has a pleated structure on its outer body, such as the pant-type diaper described in Patent Document 1, it is important that the pleated structure is not reflected in the clothing when clothing is worn over the diaper and that the pleated structure is not visible.

[0056] The underwear-like appearance of diaper 1 when worn, as described above, is the same even when diaper 1 is not worn (natural state). Therefore, diaper 1 satisfies conditions 1) and 2) above. Furthermore, in the laminated structure 13 of the outer layer sheet 11 and inner layer sheet 12 in the outer body 10, the pleat structure 20 is formed only on the inner layer sheet 12 when diaper 1 is worn or not worn, and the pleat structure is not substantially formed on the outer layer sheet 11, so the non-skin-facing surface 11b of the outer layer sheet 11 that forms the outer surface of diaper 1 is substantially flat. Here, if a bumpy structure such as the pleat structure 20 were formed on the non-skin-facing surface 11b of the outer layer sheet 11 when diaper 1 is worn, when clothing is worn over the diaper 1 in the worn state, a regular bumpy pattern corresponding to the bumpy structure may be formed on the outer surface of the clothing, which may impair the underwear-like silhouette. In contrast, with diaper 1, the non-skin-facing surface 11b of the outer layer sheet 11 is substantially flat when worn. Therefore, when clothing is worn over diaper 1 and the clothing is observed from the outside, no regular uneven pattern caused by diaper 1 is formed on the outer surface of the clothing, and the clothing maintains an underwear-like silhouette. Consequently, when clothing is worn over diaper 1, no regular uneven pattern corresponding to the pleat structure 20 is formed (reflected) on the outer surface of the clothing, making it appear as if the wearer is not wearing diaper 1.

[0057] Thus, diaper 1 satisfies all of the aforementioned conditions 1) to 3) for a diaper to look like underwear, and has the appearance of underwear.

[0058] As mentioned above, for the diaper 1 to have an underwear-like appearance when worn or not worn (natural state), it is important that the pleat structure 20 can be seen through the outer layer sheet 11 when the diaper 1 is visually observed from the outside when worn or not worn. From the viewpoint of improving the visibility of the pleat structure 20 through the outer layer sheet 11, it is preferable that the outer layer sheet 11 is thin or has a small basis weight and high light transmittance. In this regard, as shown in Figure 7, the outer layer sheet 11 of this embodiment consists of an expandable sheet 15 in which elastic filaments 17 are arranged on one side of a base sheet 16, and is substantially a single-layer structure, so it is relatively thin or has a small basis weight and high light transmittance. In other words, the diaper 1 of this embodiment makes it easy to see the pleat structure 20 through the outer layer sheet 11 when worn or not worn, and therefore it looks like underwear. Furthermore, the underwear-like appearance of the diaper 1 in this embodiment is largely due not only to the pleated structure 20 of the inner layer sheet 12, but also to the elastic filaments 17. In other words, underwear such as shorts usually has multiple weft threads intermittently arranged in the longitudinal direction, and these weft threads are one of the factors that make it look like underwear. In the stretchable sheet 15 that constitutes the outer layer sheet 11, multiple elastic filaments 17 extending in the transverse direction Y are intermittently arranged in the longitudinal direction X, and are arranged in a pattern similar to the weft threads. Therefore, if the elastic filaments 17 can be seen by visual inspection from the outside of the diaper 1, it can be perceived as underwear. The visibility of the elastic filaments 17 is improved by the structural design of the outer casing 10. Specifically, as mentioned above, the elastic filaments 17 are joined to the base sheet 16 by fusion, and as a result, on the skin-facing surface 11a of the outer layer sheet 11, many of the multiple elastic filaments 17 have a configuration in which at least a part of them penetrates into the base sheet 16 along the entire length of the elastic filament 17's extension direction (transverse direction Y). In other words, in this embodiment, the elastic sheet 15 used for the outer layer sheet 11 has elastic filaments 17 located relatively close to the non-placed surface of the elastic filaments 17, compared to a base sheet 16 where the elastic filaments 17 are bonded with adhesive without fusing them to one side (the surface forming the skin-facing surface 11a of the outer layer sheet 11). Therefore, as shown in Figure 8, when the diaper 1 is worn, it is easy to see the elastic filaments 17 through the outer layer sheet 11. This is also true for the diaper 1 when it is not worn. Furthermore, in the diaper 1 when worn, the raised ridges 22 (valleys) of the pleat structure 20 are spaced apart from the base sheet 16 and located close to the wearer's skin. Therefore, when the diaper 1 is worn, the hue of the raised ridges 22 is different from the hue of the base sheet 16 (typically white), and is perceived as skin color or a hue close to it. Therefore, when the diaper 1 is observed visually from the outside while being worn, the portion of the elastic filament 17 that overlaps with the raised portion 22 is observed against a skin-colored or similar hue, while the hue of the elastic filament 17 is typically white. As a result, the contrast between the two hues makes it easy to identify the elastic filament 17. Thus, in this embodiment, the diaper 1 allows the pleat structure 20 to be seen through the outer layer sheet 11 whether worn or not, and the elastic filaments 17 of the stretchable sheet 15 included in the outer layer sheet 11 look similar to the weft threads of underwear, thus further improving the underwear-like appearance compared to conventional pant-type absorbent products.

[0059] Furthermore, as shown in Figure 2, in this embodiment, the back panel R, which includes the area corresponding to the wearer's buttocks, has a longer vertical X length in the crotch area 10C compared to the front panel F, which does not include the area. Therefore, in the wearing state shown in Figure 8, the silhouette of the back panel R (especially the back side C and the part of the crotch area B closer to the back side C) tends to resemble that of underwear, and the fit around the buttocks is good. In addition, in this embodiment, the elastic member 9 for forming leg gathers is not placed on the back panel R, and consequently, the elastic member cover sheet that covers it is also not placed, further improving the underwear-like appearance of the back panel R.

[0060] The outer layer sheet 11 preferably includes high-basis-weight sections where the basis weight of the constituent fibers is relatively large, and low-basis-weight sections where the basis weight of the constituent fibers is relatively small. This makes it possible to ensure the necessary strength and opacity of the outer layer sheet 11 in the high-basis-weight sections, while obtaining excellent visibility of the pleated structure 20 through the low-basis-weight sections. Typically, in the outer layer sheet 11, the high-basis-weight sections and low-basis-weight sections are arranged alternately in the longitudinal direction X and / or the transverse direction Y.

[0061] The basis weight of the high basis weight portion of the outer layer sheet 11 is preferably 5 g / m². 2 Above, a comfortable 10g / m 2 The above, and preferably 50 g / m² 2 More preferably 30g / m 2 The following applies: The basis weight of the low-basis-weight portion of the outer layer sheet 11 is preferably 3 g / m². 2 In addition, a comfortable 7g / m 2 In addition, preferably 30 g / m 2 More preferably 20 g / m 2 The following applies: The total basis weight of the outer sheet 11 is preferably 5 g / m 2 or more, more preferably 10 g / m 2 or more, and preferably 50 g / m 2 or less, more preferably 30 g / m 2 or less. The ratio of the length in the longitudinal direction X or the transverse direction Y of one high-basis-weight portion of the outer sheet 11 to the length in the same direction of one low-basis-weight portion of the outer sheet 11 (「the length of the low-basis-weight portion in the longitudinal direction X / the length of the high-basis-weight portion in the longitudinal direction X」 or 「the length of the low-basis-weight portion in the transverse direction Y / the length of the high-basis-weight portion in the transverse direction Y」) is preferably 50% or more, more preferably 60% or more, and preferably 300% or less, more preferably 200% or less.

[0062] The sheet including the high-basis-weight portion and the low-basis-weight portion can be obtained, for example, by passing a sheet with a uniform basis weight between a pair of toothed groove rolls in which teeth and bottoms extending along the axial direction are alternately formed along the circumferential direction. In the sheet thus obtained, the region with a relatively large degree of stretching is the low-basis-weight portion, and the region with a relatively small degree of stretching or almost no stretching is the high-basis-weight portion. As described above, the preferred manufacturing method of the stretchable sheet 15 has a fusing step of manufacturing a composite sheet in which the elastic filaments 17 are fused to the base sheet 16, and a stretchability imparting step of imparting stretchability to the composite sheet. By subjecting the composite sheet to processing using the toothed groove roll in the stretchability imparting step, stretchability can be imparted to the composite sheet, and high-basis-weight portions and low-basis-weight portions can be formed. The sheet processing using the toothed groove roll can be carried out using the methods described in JP-A-2009-61743 or Japanese Patent No. 7481817.

[0063] From the viewpoint of further improving the visibility of the pleated structure 20 through the outer layer sheet 11, the total light transmittance of the outer layer sheet 11 is preferably high, preferably 50% or more, and more preferably 65% ​​or more. On the other hand, from the viewpoint of providing the outer layer sheet 11 with the necessary strength and opacity, the total light transmittance of the outer layer sheet 11 is preferably 95% or less, and more preferably 90% or less. In this specification, "total light transmittance" refers to the value measured in accordance with JIS K7361-1. Total light transmittance can be measured using a commercially available haze meter (for example, "NDH500" manufactured by Nippon Denshoku Industries Ltd.). The total light transmittance of the outer layer sheet 11 can be adjusted by appropriately adjusting the basis weight, thickness, density, etc. of the outer layer sheet 11.

[0064] From the viewpoint of improving the underwear-like appearance of the diaper 1 by increasing the weft-likeness of the elastic filaments 17 as described above, it is preferable that the pitch 17Px in the longitudinal direction X (see Figure 6) of the elastic filaments 17 intermittently arranged in the longitudinal direction X on the outer layer sheet 11 (stretchable sheet 15) is shorter than the pitch 14Py in the transverse direction Y of the joint 14 (see Figure 7(a)). Here, "pitch" refers to the distance between the centers of two adjacent objects (e.g., elastic filaments 17) in one direction (e.g., longitudinal direction X) in that direction. Furthermore, the pitches (14Px, 14Py, 17Px) of each part of the outer layer sheet 11 are measured when the stretchable sheet 15 is stretched to its maximum extent in its stretching direction.

[0065] The ratio of pitch 17Px to pitch 14Py, assuming pitch 17Px < pitch 14Py, is preferably 0.10 or more, more preferably 0.12 or more, and preferably 0.5 or less, and more preferably 0.3 or less, as pitch 17Px / pitch 14Py. Assuming that pitch 17Px is shorter than pitch 14Py, it is preferably 0.5 mm or more, more preferably 0.8 mm or more, and preferably 2.0 mm or less, and more preferably 1.5 mm or less. Assuming that the pitch 14Py is longer than the pitch 17Px, it is preferably 1 mm or more, more preferably 2 mm or more, and preferably 8 mm or less, and more preferably 6 mm or less. Having the pitch 14Py within the above preferred range is also preferable from the viewpoint of forming a pleated structure 20 that is highly visible through the outer layer sheet 11. Furthermore, the pitch 14Px (see Figure 7(a)) is preferably 0.5 mm or more, more preferably 1 mm or more, and preferably 7 mm or less, and more preferably 5 mm or less, from the viewpoint of improving the texture and feel of the exterior body 10.

[0066] From the viewpoint of improving the underwear-like appearance of diaper 1 and the productivity of the outer layer sheet 11 including the stretchable sheet 15, the diameter of the elastic filament 17 is preferably 40 μm or more, more preferably 80 μm or more, and preferably 200 μm or less, and more preferably 180 μm or less. If the diameter of the elastic filament 17 is too large, the weft-likeness of the elastic filament 17 may decrease, and the step caused by the elastic filament 17 may be more easily perceived when the outer layer sheet 11 is touched, which may reduce the underwear-like appearance of diaper 1. On the other hand, if the diameter of the elastic filament 17 is too small, the productivity and handling of the elastic filament 17 will become difficult, which may reduce the productivity of the outer layer sheet 11 including the stretchable sheet 15.

[0067] From the viewpoint of preventing the occurrence of the aforementioned step difference and from the viewpoint of productivity of the outer layer sheet 11 including the stretchable sheet 15, the ratio of the diameter of the elastic filament 17 in the thickness direction of the outer layer sheet 11 to the thickness of the outer layer sheet 11 is preferably 3% or more, more preferably 5% or more, preferably 200% or less, and more preferably 100% or less.

[0068] As described above, the diaper 1 of this embodiment has a distinctive structure of the stretchable sheet 15 included in the outer layer sheet 11, which allows for high visibility of the pleat structure 20 of the inner layer sheet 12 through the outer layer sheet 11, and the elastic filaments 17 of the stretchable sheet 15 have high similarity to the weft threads, resulting in an improved underwear-like appearance compared to conventional products. In addition to these improvements, the diaper 1 of this embodiment is further designed so that the appearance of the pleat structure 20 when the diaper 1 is observed from the outside while being worn is almost uniform, at least on the dorsal side C.

[0069] When the wearer directly observes the diaper 1 in the state shown in Figure 8(a), or observes it indirectly using a mirror or the like, or when a third party (e.g., an assistant who helps with putting it on) observes it, the parts that are most noticeable are the ventral part A and the dorsal part C. In particular, the dorsal part C and the part of the crotch area B closer to the dorsal part C are areas that are easily noticed and are important parts that determine the impression of the appearance of the diaper 1. Furthermore, the "appearance of the pleat structure 20" refers specifically to the degree of transparency of the pleat structure 20. Therefore, the diaper 1 of this embodiment is designed so that, when worn, the degree of transparency of the pleat structure 20 of the dorsal part C is almost uniform throughout the entire dorsal part C. This improves the underwear-like appearance, especially in the dorsal part C, which is particularly easy to notice.

[0070] To make the transparency of the pleat structure 20 more uniform when the diaper 1 is worn, it is effective to make the "basis weight when worn" of the outer body 10 including the pleat structure 20, that is, the weight per unit area of ​​the outer body 10 when worn, uniform. The outer body 10 stretches when worn, so the basis weight differs between its natural state and when worn. When the diaper 1 is worn, each part of the diaper 1 stretches to follow the wearer's body, and the basis weight of each part of the diaper 1 changes accordingly. Since the degree of stretching differs depending on the part of the body it is placed on, the basis weight of the outer body 10 in the worn diaper 1 differs in parts. Therefore, in order to make the basis weight of the outer body 10 uniform when the diaper 1 is worn, it is necessary to make the degree of stretching of the outer body 10 that occurs when the diaper 1 is worn uniform throughout the entire outer body 10. However, even when we talk about uniformizing the basis weight, the level of uniformity does not need to be extremely high (the difference in basis weight between one part of the outer casing 10 and another part is extremely small). It is sufficient if the transparency of the pleat structure 20 appears to be roughly uniform when an average consumer visually observes the diaper 1 in a worn state. Furthermore, in uniformizing the degree of stretching of the outer casing 10, it is preferable, not only in terms of the appearance but also the feel of wearing the diaper 1, to use the parts of the outer casing 10 that stretch relatively little when worn (parts located on relatively narrow parts of the wearer's body) as a reference, and to match the basis weight in the parts that stretch relatively much when worn to the basis weight in the referenced worn state. The inventors focused on the number of layers in the thickness direction of sheet members such as the outer layer sheet 11 that constitute the diaper 1, and found that by relatively increasing the number of layers in areas of the diaper 1 where the degree of stretching during wear is relatively large, and relatively decreasing the number of layers in areas where the degree of stretching is relatively small, the basis weight of the outer body 10 can be made uniform when the diaper 1 is worn.

[0071] The diaper 1 of this embodiment employs a configuration based on the above findings. Specifically, as shown in Figure 5, at least in the back panel R, the portion that overlaps with the waist region 10A in a plan view and the portion that overlaps with the torso region 10B in a plan view each have a larger number of overlapping sheets in the thickness direction of the diaper 1 (hereinafter also referred to as "number of layered sheets") compared to the portion that overlaps with the adjacent crotch region 10C in a plan view (Feature 1).

[0072] The "part overlapping with the waist region 10A in plan view" includes the waist region 10A, which is part of the exterior body 10, and the part of the member other than the exterior body 10 that overlaps with the waist region 10A in plan view. The "part overlapping with the torso region 10B in plan view" includes the torso region 10B, which is part of the exterior body 10, and the part of the member other than the exterior body 10 that overlaps with the torso region 10B in plan view. The "part overlapping with the crotch adjacent region 10C in plan view" includes the crotch adjacent region 10C, which is part of the exterior body 10, and the part of the member other than the exterior body 10 that overlaps with the crotch adjacent region 10C in plan view.

[0073] The "number of sheet layers" mentioned above is measured for sheet members that have a sheet-like appearance among the components of the absorbent article. Therefore, thread-like members such as the elastic member 8 for forming waist gathers and the elastic member 9 for forming leg gathers are not included in the measurement of the number of sheet layers. The "sheet members" mentioned above typically have a basis weight of 50 g / m². 2 The thickness is 5 mm or less under no load. Furthermore, the components that make up the absorbent body 2 (surface sheet 3, back sheet 4, and absorbent 5) are not included in the measurement of the number of sheet layers. In other words, when measuring the number of sheet layers, the number of sheet components other than those that make up the absorbent body 2 is counted. Also, if a sheet component and its folded portion are laminated, such as the folded portion 11E of the outer layer sheet 11, then each of the sheet component and the folded portion is included in the measurement of the number of sheet layers.

[0074] In this embodiment, at least in the back panel R, there is one outer layer sheet 11 and one inner layer sheet 12 in the portion that overlaps with the crotch area 10C in a plan view, so the number of sheet layers in that portion is two (see Figure 4). On the other hand, as shown in Figure 5, the portion that overlaps with the torso area 10B in a plan view and the portion that overlaps with the waist area 10A in a plan view each has a multilayer structure with three or more sheet layers, in addition to the outer layer sheet 11 and the inner layer sheet 12, one or more other sheet members (cover sheet 7, folded portion 11E, 12E, etc.) as sheet members. Therefore, this embodiment has the above-mentioned feature 1.

[0075] The portion of the back panel R that overlaps with the crotch area 10C in a plan view is positioned on the wearer's buttocks when the diaper 1 is worn. As mentioned above, the crotch area 10C is located inward in the vertical X direction (closer to the crotch area B) than the side seal portion S, and is in the same position in the vertical X direction as the leg opening LH. It is designed to follow the wearer's body without stretching, so there is virtually no stretching when the diaper 1 is worn, or if there is stretching, it is small. In contrast, the portion that overlaps with the waist area 10A in a plan view and the portion that overlaps with the torso area 10B in a plan view has elastic members that are stretchable in the horizontal Y direction, such as the elastic member 8 for forming the waist gathers and the elastic member 9 for forming the leg gathers. Therefore, when the diaper 1 is not worn (natural state), the degree of contraction in the horizontal Y direction is relatively large. However, when the diaper 1 is worn, it is positioned on a body part with a relatively large thickness (width), including the wearer's abdomen, so the degree of stretching when the diaper 1 is worn is large. Therefore, when the relative sizes of the features described in Feature 1 are established, the degree of stretching of the outer body 10 when the diaper 1 is worn is made uniform across the entire outer body 10 of the back panel R, and as a result the degree of transparency of the pleat structure 20 of the back panel R when the diaper 1 is worn becomes almost uniform, so that the appearance of the diaper 1 resembles underwear.

[0076] In this embodiment of diaper 1, in addition to feature 1, the number of sheet layers is partially varied in the waist area 10B to further equalize the transparency of the pleat structure 20 when the diaper 1 is worn. Specifically, as shown in Figures 2 and 5, at least in the back body R, the portion of the diaper 1 that overlaps with the waist area 10B in a plan view has three sections in the vertical direction X with different numbers of sheet layers. These three sections are the waist-side waist area D1 adjacent to the waist area 10A, the crotch-side waist area D3 adjacent to the crotch-side adjacent area 10C, and the central waist area D2 located between the two waist areas D1 and D3. The number of sheet layers increases in the order of waist-side waist area D1, central waist area D2, and crotch-side waist area D3 (feature 2). In other words, at least in the portion of the back panel R that overlaps with the waist area 10B in a plan view, the waist-side waist area D1 has the most sheet layers, the inseam-side waist area D3 has the fewest sheet layers, and the number of sheet layers in the central waist area D2 is intermediate between that of the two waist areas D1 and D3.

[0077] In this embodiment, as shown in Figure 5, the crotch waist area D3 has one layer each of an outer sheet 11 and an inner sheet 12 as sheet members, so the number of sheet layers in the crotch waist area D3 is 2. Also, the central waist area D2 has one layer each of an outer sheet 11, an inner sheet 12, and a cover sheet 7, so the number of sheet layers in the central waist area D2 is 3. Also, the waist area D1 has one layer each of an outer sheet 11, an inner sheet 12, a cover sheet 7, and the folded portion 12E of the inner sheet 12 as sheet members, so the number of sheet layers in the waist area D1 is 4. Therefore, in this embodiment, the relationship of "number of sheet layers in the crotch waist area D3 < number of sheet layers in the central waist area D2 < number of sheet layers in the waist area D1" as described in Feature 2 above is satisfied.

[0078] The waist circumference area D1 typically corresponds to the area from the iliac crest to the anterior superior iliac spine of the wearer when wearing diaper 1. The iliac crest and anterior superior iliac spine are anatomical terms. The iliac crest is the area indicated by Q1 in Figure 9, and the anterior superior iliac spine is the area indicated by Q2 in the same figure. The waist-side waist circumference portion D1 and the central waist circumference portion D2, in the unfolded and fully extended state of the diaper 1 as shown in Figure 2, may be a region within 2 / 3 of the total length of the side seal portion S in the vertical direction X, extending inward from the vertical end 1X of the diaper 1 (waist end 2 / 3 region). Furthermore, when the waist end 2 / 3 region is divided in half vertically X, the outer side of vertical X (the part closer to the waist region 10A) may be the waist-side waist circumference portion D1, and the inner side may be the central waist circumference portion D2. In the unfolded and fully extended state of the diaper 1 as shown in Figure 2, the crotch area D3 may be a region within 1 / 3 of the total length of the side seal S in the vertical direction X, extending outward in the vertical direction X from a virtual straight line (not shown) that extends in the horizontal direction Y through one vertical inward end Sb of a pair of side seals S, S and the other vertical inward end Sb.

[0079] In diaper 1, the portion that overlaps with the waist area 10B of the outer body 10 in a plan view is usually such that, when diaper 1 is not worn (natural state), the length in the lateral direction Y decreases as you move from the inward (crotch area B side) to the outward (waist opening WH side) in the vertical direction X. Therefore, in this state, the waist-side waist area D1 is shorter in the lateral direction Y than the crotch-side waist area D3. Furthermore, when diaper 1 is worn, the body area where the waist-side waist area D1 is located includes a relatively wide area from the iliac crest to the anterior superior iliac spine of the wearer, and especially when the wearer is an infant, it includes a relatively large area of ​​the abdomen. In contrast, the body area where the crotch-side waist area D3 is located is a relatively narrow area. Consequently, the waist-side waist area D1 stretches more with the wearing of diaper 1 than the crotch-side waist area D3. Based on this, the diaper 1 of this embodiment is designed so that the relative sizes of the features described in Feature 2 are met. As a result, the degree of stretching of each part of the diaper 1 when worn is uniform throughout the part that overlaps with the waist area 10B of the back part C in a plan view. Consequently, the degree of transparency of the pleat structure 20 in that part when the diaper 1 is worn becomes almost uniform, resulting in an improved underwear-like appearance compared to conventional products.

[0080] The diaper 1 of this embodiment, having the features 1 and 2 described above, has at least in the back body R (particularly the back side C and the part of the crotch area B closer to the back side C), the portion that overlaps with the waist area 10B in a plan view has a larger number of sheet layers than the portion that overlaps with the adjacent crotch area 10C in a plan view, and in the portion that overlaps with the waist area 10B in a plan view, the relationship "number of sheet layers in the crotch side waist area D3 < number of sheet layers in the central waist area D2 < number of sheet layers in the waist side waist area D1" holds true, so when worn, the uniformity of the transparency of the pleat structure 20 in these areas is very high, and when worn, it has a good appearance that resembles underwear.

[0081] Furthermore, the underwear-like appearance of diaper 1 is also influenced by the texture of the fabric. The texture of diaper 1 is important to evaluate in areas that are relatively thin, specifically in areas that do not overlap with the absorbent body 2 in a plan view, and more specifically, in the side flap portions located on both sides of the absorbent core 50, which forms the main body of the absorbent body 2, in the lateral direction Y. Therefore, when diaper 1 is worn, it is preferable that the pleat structure 20 can be seen through the outer layer sheet 11 when the side flap portion is observed from the outside, and it is even preferable that the transparency of the pleat structure 20 is highly uniform. Diaper 1 has such a preferable configuration.

[0082] From the viewpoint of ensuring that the effects resulting from the magnitude relationship described in Feature 2 are achieved are more reliably realized, it is preferable to set the dimensions of each part related to the magnitude relationship as follows. In the unfolded and fully extended diaper 1, the total length in the vertical direction X of the waist circumference portion D1 is preferably 5% or more, more preferably 10% or more, and preferably 30% or less, and more preferably 25% or less, of the total length in the vertical direction X of the side seal portion S. In the unfolded and fully extended state of the diaper 1, the total length in the vertical direction X of the central waist portion D2 is preferably 15% or more, more preferably 20% or more, and preferably 40% or less, and more preferably 35% or less, of the total length in the vertical direction X of the side seal portion S. In the unfolded and fully extended state of the diaper 1, the total length in the vertical direction X of the crotch waist portion D3 is preferably 25% or more, more preferably 30% or more, and preferably 55% or less, and more preferably 50% or less, of the total length in the vertical direction X of the side seal portion S.

[0083] In this embodiment, the number of sheet layers in the crotch waist area D3 is two, and the number of sheet layers is the same as that of the portion that overlaps with the adjacent crotch area 10C in a plan view. The crotch waist area D3 is adjacent to the adjacent crotch area 10C in the vertical direction X, and is a part that is easily noticeable when observing the diaper 1 in a worn state. Therefore, when evaluating the underwear-like appearance of the diaper 1 in a worn state, the state of the crotch waist area D3 tends to be used as a reference, and if the degree of stretching of the waist area D1 and the central waist area D2 is about the same as that of the crotch waist area D3, it can give the observer the impression that the transparency of the pleat structure 20 of the back body R is almost uniform. From this viewpoint, in this embodiment, the number of sheet layers in the crotch waist area D3 is the same as that of the portion that overlaps with the adjacent crotch area 10C in a plan view.

[0084] In this embodiment, as shown in Figure 5, between the waist-side waist circumference D1 and the waist region 10A, which have four layers of sheets, there is a region with three layers of sheets. That is, the portion of the diaper 1 that overlaps with the waist region 10B in a plan view has a portion other than the portion where the number of sheets increases from the inside to the outside in the vertical direction X (a portion where the number of sheets does not increase). The existence of this portion where the number of sheets does not increase can contribute to clarifying the existence of the waist region 10A.

[0085] From the viewpoint of improving the uniformity of the transparency of the pleat structure 20 of the diaper 1 when worn, it is preferable that, at least in the back body R, the following relationship of magnitude holds true for the elongation rate in the lateral direction Y between the crotch area 10C, which is part of the outer body 10, and the central waist area D2 and waist-side waist area D1, which are part of the diaper 1. Crotch area adjacent region 10C < Central waist circumference D2 < Waist side waist circumference D1 Because the above-mentioned relationship of magnitude holds true for the elongation rate in the lateral direction Y of the back body R, the elongation rate in the lateral direction Y is higher in the back body R where the degree of stretching due to wearing the diaper 1 is greater. Therefore, when wearing the diaper 1, the basis weight of the outer body 10 of the back body R is more likely to be uniform, and consequently, the degree of transparency of the pleat structure 20 of the back body R is more likely to be uniform. The stretch rate of each part of diaper 1 can be measured by the measurement method B described below. When measuring the stretch rate in the lateral direction Y of the crotch area adjacent to the waist area 10C, the central waist area D2, and the waist side waist area D1 by the measurement method B described below, the measurement targets for the stretch rate of these three measurement targets are parts that do not overlap with the absorbent core 50 in a plan view (for example, the side flap parts), and the three measurement targets are in approximately the same position in the lateral direction Y. The elongation rate can be adjusted by appropriately adjusting the thickness of the member, the basis weight, the placement or absence of elastic members, and, if elastic members are placed, their expansion and contraction characteristics.

[0086] <Method for measuring elongation rate B> If the object to be measured for elongation is one of the components of an absorbent article (for example, the outer casing 10), the object to be measured is removed from the absorbent article. This removal of the object to be measured can be done, for example, by weakening the bonding force between the two components by spraying a cold spray onto the adhesive that joins the object to be measured to other components in the absorbent article, and then carefully peeling the object to be measured away from the other components. The member to be measured or the absorbent article to be measured is placed in its natural state, and two marks are made on the sheet member constituting the skin-facing or non-skin-facing surface of the area to be measured, with a 20 mm gap between them in the direction of expansion and contraction (lateral direction Y) of the area to be measured. The marks can be made with an oil-based pen or the like. Next, with the sheet member stretched to its maximum extent, the distance between the two marks is measured as the stretch distance (mm). Then, the stretch rate of the area to be measured is calculated using the following formula. The stretch rate measured by this measurement method B is the maximum stretch rate. Elongation rate of the measured area (%) = [Elongation distance (mm) / 20 (mm)] × 100

[0087] The elongation rate of the crotch area 10C in the back panel R is preferably 100% or more, more preferably 120% or more, and preferably 250% or less, and more preferably 220% or less, assuming that the above-mentioned relationship of magnitude holds true. The elongation rate of the central waist circumference D2 in the back panel R is preferably 130% or more, more preferably 150% or more, and preferably 170% or less, and more preferably 240% or less, assuming that the above-mentioned relationship of magnitude holds true. The elongation rate of the waist circumference portion D1 on the back panel R is preferably 150% or more, more preferably 170% or more, and preferably 300% or less, and more preferably 260% or less, assuming that the above-mentioned relationship of magnitude holds true.

[0088] The portion of the back panel R that overlaps with the crotch area 10C of the outer covering 10 in a plan view is often an important part that determines the overall appearance of the diaper 1. Therefore, it is preferable that it reliably possesses the features necessary to give it an underwear-like appearance (such as high visibility of the pleat structure 20 and elastic filaments 17 through the outer layer sheet 11). From this viewpoint, it is preferable that at least the portion of the back panel R that overlaps with the crotch area 10C in a plan view has only an outer layer sheet 11 and an inner layer sheet 12 as sheet members, as shown in Figure 5.

[0089] Furthermore, in the diaper 1, the portion that overlaps with the waist region 10A of the outer body 10 in a plan view has an elastic member 8 for forming waist gathers that extends in the lateral direction Y. This configuration is basically the same as the portion of underwear such as shorts that corresponds to the wearer's waist. Therefore, the portion of the diaper 1 that overlaps with the waist region 10A in a plan view inherently has an appearance similar to underwear, and it is easy to see as underwear when viewed from the outside without any special measures to make it look like underwear. On the other hand, when putting on or taking off the diaper 1, the wearer often hooks their fingers into the portion that overlaps with the waist region 10A in a plan view to raise and lower the diaper 1. From the viewpoint of facilitating such operations, it is preferable that this portion is of high strength and relatively thick, and specifically, it is preferable that it has a larger number of sheet layers (i.e., has the above-mentioned feature 1) compared to the portion that overlaps with the adjacent crotch region 10C in a plan view. Considering the above, it is preferable that the number of sheet layers in the area overlapping with the waist region 10A in a plan view of diaper 1 be at least 3 layers more than the number of sheet layers in the area overlapping with the adjacent crotch region 10C in a plan view, and also more than the number of sheet layers in the waist area D3 on the crotch side. Furthermore, the portion of diaper 1 that overlaps with the waist region 10A in a plan view may have a uniform number of sheet layers, or it may have multiple portions that differ from each other. In the embodiment shown in Figure 5, the latter is adopted, and in the portion of diaper 1 that overlaps with the waist region 10A in a plan view, the number of sheet layers on the waist region 10B side is 3, and the number of sheet layers on the vertical end 1X side of diaper 1 is 4.

[0090] The aforementioned features of the present invention, including features 1 and 2 (techniques for giving an absorbent article an underwear-like appearance), can be applied not only to the back panel R but also to the front panel F, unless otherwise specified.

[0091] Figure 10 shows some other embodiments of the pant-type absorbent article of the present invention. For the other embodiments described later, configurations different from those of diaper 1 described above will be explained, while components similar to those of diaper 1 will be denoted by the same reference numerals and their descriptions will be omitted. For configurations not specifically described in the embodiments described later, the descriptions of diaper 1 described above will apply as appropriate.

[0092] Diaper 1A shown in Figure 10 differs from diaper 1 shown in Figure 5, which has feature 2, in that the number of sheet layers is equal in the waist circumference portion D1 and the central waist circumference portion D2, and it does not have feature 2. Diaper 1A also achieves the predetermined effect of the present invention, which is to have an appearance similar to underwear.

[0093] In diaper 1A, as shown in Figure 10, the folded portion 12E of the inner layer sheet 12 and the cover sheet 7 are continuous without gaps in the vertical direction X from the boundary between the waist region 10A and the torso region 10B to the outer end of the absorbent material 5 in the vertical direction X, and in diaper 1 as described above, the two overlap in a plan view (see Figure 5). With this configuration, there are no areas where the number of sheet layers is two in the waist-side torso region D1 and the central torso region D2, where the degree of stretching of the outer body 10 when wearing the diaper is relatively large, and an improvement in the uniformity of the transparency of the pleat structure 20 described above can be expected. In addition, the area from the boundary between the waist region 10A and the torso region 10B to the outer end of the absorbent material 5 in the vertical direction X is an area where fingers are often caught when putting on or taking off the diaper, and with this configuration the strength is improved so that problems such as tearing and holes can be prevented.

[0094] The present invention can be applied to panty-type absorbent articles. The term "absorbent article" as used herein broadly includes articles used to absorb bodily fluids (urine, loose stool, menstrual blood, sweat, etc.) discharged from the human body, and in addition to the disposable diapers mentioned above, it also includes, for example, menstrual panties.

[0095] Although the present invention has been described above based on its preferred embodiments, the present invention is not limited in any way to the above embodiments and can be modified as appropriate without departing from the spirit of the invention. In the above embodiment, the outer casing 10 had a laminated structure 13 only on the ventral portion A and the dorsal portion C, but it may also have a laminated structure 13 on the crotch area B. In the above embodiment, the outer layer sheet 11 was a combination of multiple sheets 110, 111, but it may also be a single sheet, similar to the inner layer sheet 12. In that case, the entire outer casing 10 is a laminated structure 13 of the outer layer sheet 11 and the inner layer sheet 12.

[0096] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to such examples.

[0097] [Example 1] A disposable pull-up diaper with a basic structure similar to diaper 1 shown in Figure 1 was manufactured. Specifically, Example 1 was created by changing the outer casing of a commercially available disposable pull-up diaper (manufactured by Kao Corporation, product name "Just Like Underwear") to the outer casing 10 described above. In the diaper of Example 1, the number of sheet layers in the waist-side waist area D1 of the back body R was 4, the number of sheet layers in the central waist area D2 was 3, the number of sheet layers in the crotch-side waist area D3 was 2, and the number of sheet layers in the portion of the diaper that overlaps with the crotch-adjacent area 10C of the outer body 10 in a plan view (hereinafter also referred to as the "crotch-adjacent area arrangement portion") was 2. The crotch-adjacent area arrangement portion was an area within 90 mm inward in the vertical direction X from a virtual straight line extending in the horizontal direction Y through the vertical inward end Sb of each of the pair of side seal portions S, S. The outer casing 10 used in Example 1 consisted of an outer layer sheet 11 made of an expandable sheet 15 and an inner layer sheet 12 that was non-stretchable and non-elastic. The inner layer sheet 12 was made of white spunbond nonwoven fabric (basis weight 18 g / m²). 2 The stretchable sheet 15 was made of a non-stretchable and non-stretchable white spunbond nonwoven fabric (basis weight 18 g / m²). 2 The stretchable sheet 15 had a structure in which multiple elastic filaments 17 were fused to one side of a base sheet 16 made of styrene-ethylene-propylene-ethylene block copolymer so as to be expandable and contractible in the lateral direction Y (hereinafter also referred to as "single-layer stretchable sheet"). The stretchable sheet 15 was manufactured using the method described in Japanese Patent Publication No. 7481817, and sheet processing using a toothed roll was performed during the manufacturing process. As a result, the stretchable sheet 15 (base sheet 16) contained a high basis weight portion in which the basis weight of the constituent fibers was relatively large, and a low basis weight portion in which the basis weight of the constituent fibers was relatively small. Styrene-ethylene-propylene-ethylene block copolymer was used as the raw material for the elastic filaments 17. The total light transmittance of the stretchable sheet 15 (single-layer stretchable sheet) used in Example 1 was 81%.

[0098] [Reference example 1] Reference Example 1 is a disposable pant-type diaper with the same configuration as Example 1, except that instead of the stretchable sheet 15, a configuration was used in which multiple elastic filaments 17 were fused between two opposing base sheets 16, 16 of the same type so as to be stretchable in the lateral direction Y (hereinafter also referred to as "laminated stretchable sheet"). The total light transmittance of the laminated stretchable sheet used in Reference Example 1 was 62%. In the diaper of Reference Example 1, the number of sheet layers in the waist area D1 of the back body R was 5 layers, the number of sheet layers in the central waist area D2 was 4 layers, the number of sheet layers in the crotch area D3 was 3 layers, and the number of sheet layers in the part of the outer body 10 of the diaper that overlaps with the adjacent crotch area 10C in a plan view was 3 layers.

[0099] [Reference example 2] Reference Example 2 is a disposable pant-type diaper with the same configuration as Example 1, except that the number of sheet members in the back panel R was adjusted and the number of sheet layers was changed as shown in Table 1 below.

[0100] [Evaluation Test] For the diapers of Example 1 and Reference Example 2, the elongation rate in the lateral direction Y of the crotch area 10C, the waist-side waist circumference D1, and the central waist circumference D2 in the worn state was measured using a method similar to measurement method B. Specifically, in measurement method B, a sheet member with two marks on each part of Example 1 and Reference Example 2 (crotch area 10C, waist-side waist circumference D1, and central waist circumference D2) was attached to an adult-sized model without being fully stretched, and the distance between the two marks was measured as the elongation distance. Otherwise, the measurement was performed in the same manner as measurement method B. For the diaper of Example 1, the maximum elongation rate of each part was measured using measurement method B. In addition, for the diapers of Example 1 and Reference Example 1, the visibility rate of the folds in the crotch area of ​​the back panel R of the diaper in its natural state, the visibility of the elastic filaments, and the similarity in appearance to underwear fabric were evaluated using the methods described below. Furthermore, for the diapers of Example 1 and Reference Example 2, the visibility of the folds in each part of the back panel R of the diaper while worn was evaluated using the method described below. The results are shown in Table 1 below.

[0101] <Method for evaluating the visibility rate of folds> This evaluation method was conducted in a room with standard brightness (410 lux) with the indoor lights on. A rectangular black cardboard sheet measuring 90 mm in length and 130 mm in width was placed on the inner surface (skin-facing side) of the evaluation area of ​​the diaper (the area adjacent to the crotch of the back panel R). A square frame measuring 30 mm in length and 30 mm in width was drawn with an oil-based pen in the area on the outer surface (non-skin-facing side), which is the opposite side of the evaluation area, where it overlaps with the black cardboard sheet in a plan view. Next, the area within the frame was visually observed, and the number of visible folds (relatively darker areas extending in the vertical direction X, corresponding to the raised ridges 22) (N1) was counted. The number of actual folds (raised ridges 22) within the frame (N0) was also counted. The measurement of N0 was performed by exposing the pleat-forming surface (skin-facing surface) of the inner layer sheet that forms the pleats and visually observing the pleat-forming surface. The pleat visibility rate was then calculated using the following formula. Fold visibility rate (%) = (N1 / N0) × 100 The evaluation was conducted by a panel of three experts, and the average of the fold visibility rates calculated by each expert panel was used as the fold visibility rate for the evaluated area.

[0102] <Method for evaluating the visibility of elastic filaments> This evaluation method was conducted in a room with standard brightness (410 lux) with the indoor lights on. Three expert panelists visually observed the evaluation area of ​​the diaper (the area adjacent to the crotch on the back panel R) from the outside and scored the visibility of the elastic filaments according to the evaluation criteria below. The average score of the three panelists' results was used as the evaluation result for the diaper being evaluated. (Evaluation Criteria) 5 points: It's easy to see. 4 points: Slightly visible. 3 points: Neither agree nor disagree. 2 points: It's not very visible. 1 point: It's almost invisible.

[0103] <Method for evaluating the visual similarity with underwear fabric> This evaluation method was conducted in a room with standard brightness (410 lux) with the indoor lights on. Three expert panelists visually observed the evaluation area of ​​the diaper (the area adjacent to the crotch on the back panel R) from the outside and scored the similarity in appearance to underwear fabric according to the evaluation criteria below. The average score of the three panelists' results was used as the evaluation result for the diaper being evaluated. (Evaluation Criteria) 5 points: Very similar. 4 points: Somewhat similar. 3 points: Neither agree nor disagree. Points 2: They don't look very similar. 1 point: They don't look alike at all.

[0104] <Method for evaluating the visibility of folds when worn> This evaluation method was conducted in a room with standard lighting (410 lux) with the indoor lights on. The diaper under evaluation was fitted to an adult-sized model, and three expert panelists visually inspected the outer surface of each part of the back of the diaper (waist area, central waist area, crotch area, and area adjacent to the crotch) and scored it according to the evaluation criteria below. The average score of the three panelists' results was used as the evaluation result for the diaper under evaluation. (Evaluation Criteria) 5 points: It's easy to see. 4 points: Slightly visible. 3 points: Neither agree nor disagree. 2 points: It's not very visible. 1 point: It's almost invisible.

[0105] [Table 1]

[0106] As shown in Table 1, the diaper of Example 1 received a better evaluation of the placement of the area adjacent to the crotch of the back panel in a natural state compared to the diaper of Reference Example 1. One of the main reasons why the diaper of Example 1 received a higher evaluation than the diaper of Reference Example 1 is presumed to be that the diaper of Example 1 used a single-layer stretchable sheet, which is thinner than the laminated stretchable sheet used in the diaper of Reference Example 1, as the outer layer sheet (stretchable sheet) that forms the outer surface of the diaper. Furthermore, in Example 1, the visibility of the pleats in each part of the back of the diaper when worn was evaluated at 4.7 out of 5 points, indicating that the pleat structure of the inner layer sheet can be confirmed through the outer layer sheet by visual observation. In contrast, in Reference Example 2, the visibility of the pleats in the area adjacent to the crotch and the waist area on the crotch side of the diaper was as good as in Example 1, but the visibility of the pleats in the waist area and the central waist area, which are located further outward in the vertical direction, was inferior. One of the main reasons why the diaper of Example 1 is rated higher than the diaper of Reference Example 2 is that in the diaper of Example 1, the area overlapping with the waist area in a plan view has a larger number of sheet layers compared to the area adjacent to the crotch, and the relationship "number of sheet layers in the crotch area < number of sheet layers in the central waist area < number of sheet layers in the waist area" holds true in the area overlapping with the waist area in a plan view. [Explanation of Symbols]

[0107] 1.1A Pant-type disposable diapers (pant-type absorbent items) X vertical direction Y (horizontal direction) F Front R Back A. Ventral part B Inseam C dorsal part D1 Waist circumference D2 Central waist area D3 Inseam waist circumference S Side seal section 10 Exterior 10A Waist area 10B Waist area 10C Inner thigh adjacent area 11. Outer layer sheet 110 Ventral outer layer sheet 111 Dorsal outer layer sheet 11E Folded portion of the outer layer sheet 12 Inner layer sheet 12E Folded portion of the inner layer sheet 13 Laminated structure 14 Joint 15 Stretchable Sheet 16 Base sheet 17 Elastic filaments 20 Pleated structure 21 Concave section 22 Convex part 22A Hollow section of the raised ridge

Claims

1. A pair of pants-type absorbent article having a longitudinal direction extending from the wearer's abdominal side through the crotch to the back and a transverse direction perpendicular to the longitudinal direction, and divided into an inseam section located in the crotch area, an abdominal section located on the wearer's abdominal side of the inseam section, and a dorsal section located on the wearer's back side of the inseam section, an absorbent body that absorbs and retains bodily fluids, and an outer casing located on the non-skin-facing side of the absorbent body, wherein the side edges of the outer casing along the longitudinal direction in the front and back panels are joined together to form a pair of side seals, a waist opening, and a pair of leg openings, The outer casing has a laminated structure in the ventral and dorsal portions comprising an outer layer sheet forming the outer surface of the pant-type absorbent article and an inner layer sheet joined to the skin-facing surface of the outer layer sheet via a joint. The outer layer sheet includes the stretchable sheet having elasticity in the lateral direction, Multiple joints are intermittently arranged in both the vertical and horizontal directions. In the state in which the aforementioned pant-type absorbent article is worn, the inner layer sheet of the laminated structure has a pleated structure consisting of a plurality of recessed portions extending in the longitudinal direction with the joint portion at the bottom, and hollow convex portions located between the recessed portions. A pant-type absorbent article wherein, when the pant-type absorbent article is worn, the pleated structure can be confirmed through the outer layer sheet when the pant-type absorbent article is visually observed from the outside.

2. The outer garment, at least in the back, includes the opening edge of the waist opening, has an elastic member for forming waist gathers, and has a waist region located at the outermost vertical point, a torso region adjacent to the waist region, and a crotch region adjacent to the torso region. The boundary between the waist area and the adjacent crotch area is a virtual straight line extending in the lateral direction through one of the longitudinal inward ends of the pair of side seal portions and the other longitudinal inward end. The pant-type absorbent article according to claim 1, wherein the portion that overlaps with the waist region in a plan view and the portion that overlaps with the torso region in a plan view each have a larger number of overlapping sheets in the thickness direction of the pant-type absorbent article compared to the portion that overlaps with the adjacent crotch region in a plan view.

3. The portion of the pant-type absorbent article that overlaps with the waist area in a plan view has three sections in the vertical direction, each with a different number of overlapping sheets in the thickness direction of the pant-type absorbent article, and these three sections are a waist-side waist section adjacent to the waist area, a crotch-side waist section adjacent to the crotch-side adjacent area, and a central waist section located between the two waist sections. The pant-type absorbent article according to claim 2, wherein the number of sheets increases in the order of waist circumference, central circumference, and crotch circumference.

4. The pant-type absorbent article according to claim 3, wherein the following relationship of magnitude holds true for the lateral elongation rate. The area adjacent to the crotch < The central waist area < The waist side waist area

5. The pant-type absorbent article according to claim 2 or 3, wherein the portion that overlaps with the adjacent crotch area in a plan view has only the outer layer sheet and the inner layer sheet as a sheet member.

6. The pant-type absorbent article according to claim 1 or 2, wherein the outer layer sheet includes a high-basis-weight portion in which the basis weight of the constituent fibers is relatively large and a low-basis-weight portion in which the basis weight of the constituent fibers is relatively small.

7. The outer layer sheet comprises a base sheet and a plurality of elastic filaments arranged on one side of the base sheet so as to be stretchable in the lateral direction, and the elastic filaments 17 are joined to the base sheet by fusion. The pant-type absorbent article according to claim 1 or 2, wherein the non-arranged surface of the elastic filament in the base sheet forms the outer surface of the pant-type absorbent article.

8. The plurality of elastic filaments are intermittently arranged in the longitudinal direction, The pants-type absorbent article according to claim 7, wherein the longitudinal pitch of the elastic filaments is shorter than the transverse pitch of the joint.

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