JP7828861B2 - Pant-type disposable diapers - Google Patents

Description

This invention relates to disposable diapers in the form of pants.

Pants-type disposable diapers generally consist of an absorbent core that serves as the main absorbent area, and an outer casing positioned on the non-skin-facing side of the absorbent core. Furthermore, considering factors such as comfort and absorbency, it is known that the absorbent core may have openings or low-basis-weight sections, and that the outer casing may include leg elastic members that form leg gathers at the opening edges of the leg openings.
For example, the applicant previously proposed a pant-type absorbent article comprising an outer casing having a stretchable outer layer sheet and leg elastic members, and an absorbent core formed with an opening extending in the vertical direction, wherein the opening has an opening on the skin-facing side or a non-skin-facing side (Patent Document 1).

Patent Document 2 discloses a pant-type absorbent article comprising an absorbent body with slits, and a rear outer back sheet having an elastic member that forms leg gathers and transverse gathers of the absorbent body at the middle crotch edge.

Patent No. 6559940 Patent No. 5486347

While the aforementioned leg elastic members are effective in providing a good fit around the wearer's legs, if the leg elastic members and absorbent material overlap as shown in Patent Document 2, the absorbent material may come into excessive contact with the wearer's skin as the leg elastic members contract, potentially reducing the wearing comfort. Conversely, if the absorbent material does not come into contact with the skin sufficiently, its absorbent performance may decrease.
The pant-type disposable diapers described in Patent Documents 1 and 2 had room for improvement in balancing the absorbent performance of the absorbent material with a comfortable fit.

This invention relates to providing a pant-type disposable diaper that achieves both high absorbency and comfortable wear.

The present invention relates to a pant-type absorbent article comprising an absorbent body having an absorbent core, an absorbent body having an absorbent core, and an outer body disposed on the non-skin-facing side of the absorbent body, having a longitudinal direction extending from the ventral direction through the crotch to the ventral direction and a transverse direction perpendicular to the longitudinal direction, and divided by the center of the longitudinal direction into a front body that is disposed on the ventral side of the wearer when worn and a back body that is disposed on the back side of the wearer, and having a waist opening and a pair of leg openings.
In one embodiment, it is preferable that the outer garment has a front stretchable region on the front body that stretches along the lateral direction, a rear stretchable region on the back body that stretches along the lateral direction, and a non-stretchable region located between the front stretchable region and the rear stretchable region.
In one embodiment, the absorbent core comprises a lower core and an upper core positioned on the skin-facing side of the lower core, wherein the entire upper core is preferably located within the non-stretchable region.
In one embodiment, it is preferable that the lower core has a lower low-rigidity portion extending in the vertical direction and a lower high-rigidity portion having higher rigidity than the lower low-rigidity portion.
In one embodiment, it is preferable that the upper core has an upper low-rigidity portion extending in the vertical direction and an upper high-rigidity portion that has higher rigidity than the upper low-rigidity portion.
In one embodiment, the exterior body preferably has a leg elastic member that forms a leg gather, and the leg elastic member preferably has a first portion that runs along the periphery of the leg opening and a second portion that is continuous with the first portion and extends toward the lateral center.
In one embodiment, it is preferable that the exterior body has a pre-cut region between the second portions of the left and right leg elastic members in which no stretching or contracting occurs.
In one embodiment, it is preferable that in the pre-cut region, the end high-rigidity portion located further outward in the vertical direction than the upper low-rigidity portion overlaps the lower low-rigidity portion in a plan view.

The present invention provides a disposable pant-type diaper that achieves both high absorbency and comfortable wear.

Figure 1 is a diagram showing one embodiment of the pants-type disposable diaper of the present invention, and is a schematic unfolded plan view showing the skin-facing side of the diaper in an unfolded and stretched state. Figure 2 is a schematic unfolded plan view showing the non-skin-facing side of the disposable diaper shown in Figure 1. Figure 3 is an exploded perspective view of the disposable diaper shown in Figure 1. Figure 4 is a cross-sectional view taken along line II-II in Figure 1. Figure 5 is a cross-sectional view taken along the line III-III in Figure 1. Figure 6 is an enlarged plan view of the pre-cut area shown in Figure 1. Figure 7 is a schematic cross-sectional view illustrating the effects of the disposable diaper shown in Figure 1. Figure 8 is a plan view showing the joint connecting the outer casing and the absorbent body shown in Figure 1.

The present invention will be described below with reference to the drawings, based on preferred embodiments thereof. Figures 1 to 8 show one embodiment of the pants-type disposable diaper 1 of the present invention (hereinafter simply referred to as "diaper 1").
As shown in Figures 1 and 2, diaper 1 has an abdominal portion A that is positioned on the wearer's abdominal side when worn, a dorsal portion B that is positioned on the wearer's back side, and a crotch portion C located between the abdominal portion A and the dorsal portion B. The crotch portion C is the part that is positioned in the wearer's crotch area when diaper 1 is worn. The abdominal portion A is the part that is positioned on the wearer's abdominal side, i.e., in front of the crotch portion C when diaper 1 is worn. The dorsal portion B is the part that is positioned on the wearer's back side, i.e., in rear of the crotch portion C when diaper 1 is worn.
As shown in Figures 1 and 2, diaper 1 has a longitudinal direction X corresponding to the wearer's front-to-back direction and a transverse direction Y perpendicular to it. In this specification, "wearer's front-to-back direction" refers to the direction extending from the wearer's ventral side through the crotch area to the dorsal side. Diaper 1 extends in the longitudinal direction X from the ventral side A through the crotch area C to the dorsal side B.

As shown in Figures 1 and 2, diaper 1 is divided into a front panel F, which is positioned on the front (abdominal) side of the wearer when worn, and a back panel R, which is positioned on the back (rear) side of the wearer, with the vertical center line (vertical center line CLx) as the boundary. The vertical center line CLx is a hypothetical straight line that bisects diaper 1 in the vertical direction X when it is unfolded and stretched, as shown in Figures 1 and 2, and extends in the horizontal direction Y. The "unfolded and stretched state" of diaper 1 refers to the state in which diaper 1 is separated at the side seal section described later to unfold it, and then the elastic members of each part of the unfolded diaper 1 are stretched to the design dimensions (the same dimensions as when it is spread flat with the influence of the elastic members completely eliminated).
In this specification, unless otherwise specified, the dimensions of each part of the diaper 1 (e.g., the absorbent core 40), such as the length (width) in the vertical X or horizontal Y direction, refer to the dimensions (design dimensions) when the elastic members of each part are stretched and the members are extended.

The diaper 1 comprises an absorbent body 5 having a liquid-retaining absorbent material 4, and an outer casing 3 positioned on the non-skin-facing side of the absorbent body 5. The outer casing 3 has both side edges AS and BS along the longitudinal direction X on the ventral portion A and dorsal portion B, respectively, joined together by known joining means such as adhesive, heat sealing, or ultrasonic sealing. As a result, the diaper 1 has a pair of side seal portions (not shown) where the side edges AS and BS are joined, and further has a waist opening through which the wearer's torso passes, and a pair of leg openings (not shown) through which the wearer's lower limbs pass.

In this specification, "skin-facing surface" refers to the surface of a disposable diaper or its components (e.g., the surface sheet 12) that faces the wearer's skin when the diaper is worn, i.e., the side relatively closer to the wearer's skin. "Non-skin-facing surface" refers to the surface of a disposable diaper or its components that faces away from the skin when the diaper is worn, i.e., the side relatively further away from the wearer's skin. "When worn" here means the normal, proper wearing position, i.e., the state in which the absorbent article (disposable diaper) is correctly worn.

The absorbent body 5 has a rectangular shape in plan view and extends in the vertical direction X. Its longitudinal direction coincides with the vertical direction X of the diaper 1 when unfolded and extended, and it is positioned in the center of the outer casing 3 in the horizontal direction Y. The absorbent body 5 is joined to the outer casing 3 by known bonding means such as an adhesive.
In this embodiment, the absorbent body 5 has its skin-facing surfaces at both ends in the vertical direction X covered with end fixing sheets 34, 34 and is fixed to the outer casing 3. The end fixing sheets 34 are joined to the outer casing 3 and the absorbent body 5 by known bonding means such as adhesives (see Figures 1 and 3).

The absorbent body 5 comprises a liquid-permeable surface sheet 12 that forms the skin-facing surface, a liquid-impermeable, liquid-difficult-permeable, or water-repellent leak-proof sheet 13 that forms the non-skin-facing surface, and a liquid-retaining absorbent body 4 disposed between the surface sheet and the leak-proof sheet 13, all of which are integrated by known bonding means such as an adhesive.
As shown in Figure 4, the absorbent body 4 of this embodiment is composed of an absorbent core 40 and a core wrap sheet 49 that covers the surface of the absorbent core 40. In this embodiment, the entire surface of the absorbent body 4, including the skin-facing surface and the non-skin-facing surface, is covered with the core wrap sheet 49. Alternatively, the absorbent core 40 may have its skin-facing surface covered with a liquid-permeable core wrap sheet 49. Furthermore, the absorbent body 4 does not necessarily have to include the core wrap sheet 49. Details of the absorbent core 40 will be described later.

The absorbent body 5 of this embodiment has elastic members 48 (hereinafter also referred to as "intermediate elastic members 48") extending in the vertical direction X on both sides in the lateral direction Y. The intermediate elastic members 48 of this embodiment are arranged in an extended state between the surface sheet 12 and the leak-proof sheet 13 on the outer side of the absorbent body 4 in the lateral direction Y.
If the absorbent body 5 includes an intermediate elastic member 48, the intermediate elastic member 48 may be positioned in an extended state between the core wrap sheet 49 and the absorbent core 40, or between the surface sheet 12 and the absorbent core 40. Furthermore, the position of the intermediate elastic member 48 in the height direction Z is not particularly limited, and its position in the height direction Z may differ between the unfolded and extended state of the diaper 1 and the natural state of the diaper 1. For example, the intermediate elastic member 48 may be positioned approximately in the center of the height of the absorbent body 4 in the natural state, or it may be positioned on the non-skin-facing side of the center of the height of the absorbent body 4 in the unfolded and extended state.

The diaper 1 of this embodiment has a pair of leak-proof cuffs 6, 6 made of a liquid-resistant or water-repellent and breathable sheet material on both the left and right sides along the longitudinal direction X on the skin-facing surface of the absorbent body 5 (see Figures 1 and 4). The leak-proof cuff 6 of this embodiment has a cuff-forming sheet 60 and a cuff elastic member 61, with the cuff elastic member 61 positioned in an extended state between two folded cuff-forming sheets 60. The inner end of the leak-proof cuff 6 in the lateral direction Y is a free end, and the outer end in the lateral direction Y is wrapped around the non-skin-facing side of the absorbent body 5, i.e., the non-skin-facing side of the leak-proof sheet 13, and fixed between the leak-proof sheet 13 and the outer casing 3 with an adhesive or the like. Near the free end of the leak-proof cuff 6, one or more thread-like cuff elastic members 61 extending in the longitudinal direction X are positioned in an extended state (see Figure 4). The leak-proof cuff 6 stands upright at least in the crotch area C when the cuff elastic member 61, which is positioned in an extended state, contracts, thereby preventing the outflow of excretory fluids such as urine in the lateral direction Y outwards.
For the sake of clarity, the leak-proof cuff 6 is not shown in Figure 3.

The outer casing 3 forms the outer shape of the diaper 1, that is, the outer shape of the ventral part A, the crotch area C, and the dorsal part B. As shown in Figures 1 and 2, in a plan view when unfolded and extended, the outer casing 3 has a rectangular shape in the ventral part A and dorsal part B, where the length in the lateral direction Y is longer than the length in the longitudinal direction X, and in the crotch area C, both side edges along the longitudinal direction X, that is, a pair of leg edges LE, LE, are hourglass-shaped, tapering inward in the lateral direction Y. In this embodiment, in a plan view when unfolded and extended, both side edges along the longitudinal direction X of the ventral part A and dorsal part B protrude outward in the lateral direction Y than both side edges along the longitudinal direction X of the crotch area C. Furthermore, the outer casing 3 has a longitudinal X outer edge WE of the ventral part A and a longitudinal X outer edge WE of the dorsal part B that extends in the lateral direction Y, forming a waist opening in the diaper 1 where the side seal portion is formed. In other words, these vertical X-shaped outer edges become the peripheral edge WE of the waist opening.

The outer casing 3 is constructed by laminating multiple sheets. In this embodiment, as shown in Figure 3, the outer casing 3 is constructed by laminating an outer layer sheet 31, an inner layer sheet 33, and a fixing sheet 35 in that order from the non-skin-facing side to the skin-facing side. The outer layer sheet 31 forms the outer surface of the diaper 1, i.e., the non-skin-facing side, at least in the ventral A and dorsal B portions, and as shown in Figures 1 and 3, it is divided into a front outer layer sheet 31a located on the front body F and a rear outer layer sheet 31b located on the back body R. The inner layer sheet 33 is located between the outer layer sheet 31 and the fixing sheet 35 and is fixed by being spanned across both outer layer sheets 31a and 31b of the front body F and back body R. In this embodiment, the inner layer sheet 33 is continuous in the vertical direction X from the peripheral edge WE of the waist opening of the ventral A portion to the peripheral edge WE of the waist opening of the dorsal B portion. In other words, the inner layer sheet 33 is continuous along the entire length of the diaper 1, and the front outer layer sheet 31a and the rear outer layer sheet 31b in the longitudinal direction X form the outer surface of the diaper 1. The fixing sheet 35 is positioned on the skin-facing side of the inner layer sheet 33 and fixes the leg elastic member 37 (described later) between it and the inner layer sheet 33. These sheets 31, 33, and 35 constituting the outer casing 3 are joined together by known bonding means such as adhesives.

In this embodiment, the outer layer sheet 31a and 31b of the outer layer sheet 31a and 31b are folded back towards the skin-facing side along the peripheral edge WE of the waist opening (see Figure 3). That is, the outer layer sheets 31a and 31b form the peripheral edge WE of the waist opening, and the folded portion of the sheets 31a and 31b extends inward in the vertical direction X from the peripheral edge WE.
In this embodiment, the inner layer sheet 33 of the outer casing 3 is also folded back along the peripheral edge WE of the waist opening towards the skin-facing side, similar to the outer layer sheets 31a and 31b described above. Near the peripheral edge WE of the waist opening of the outer casing 3, the folded portions of the outer layer sheets 31a and 31b and the folded portion of the inner layer sheet 33 overlap on the skin-facing side (see Figure 5).

The outer casing 3 of this embodiment is equipped with a plurality of thread-like or strip-like elastic members 32 that are sandwiched and fixed in an extended state in the folded portion of the inner layer sheet 33. Specifically, in the areas of the ventral portion A and the dorsal portion B that are positioned around the wearer's waist, a plurality of elastic members 32 (hereinafter referred to as "waist elastic members 32") are intermittently arranged in an extended state in the lateral direction Y and at predetermined intervals in the longitudinal direction X. The waist elastic members 32 are positioned between the side edges along the longitudinal direction X in the ventral portion A and the dorsal portion B, that is, between the side seal portions in the lateral direction Y, and in an area extending outward in the longitudinal direction X from the end edge of the absorbent body 5 in the longitudinal direction X. Such areas are positioned around the wearer's waist and its vicinity when worn. The waist elastic members 32 extend over substantially the entire length in the lateral direction Y of the ventral portion A and the dorsal portion B in the outer casing 3 and are positioned in a state in which elastic stretchability is exhibited. This creates a substantially continuous, annular waist gather along the entire circumference of the waist opening.

The outer casing 3 has a plurality of thread-like or strip-like leg elastic members 37 arranged in an extended state between the inner layer sheet 33 and the fixing sheet 35. Specifically, one or more leg elastic members 37 that form leg gathers are arranged in an extended state on the leg edge portions LE that form the periphery of each of the pair of leg openings in the front body F (see Figures 1 and 2). The leg elastic members 37 are arranged on each of the left and right leg edge portions LE in the front body F. These leg elastic members 37 form leg gathers on the periphery of each of the pair of leg openings in the front body F. In this embodiment, the diaper 1 has leg elastic members 37 only on the front body F. That is, the back body R does not have leg elastic members 37.
Alternatively, leg elastic members 37 may be provided at the leg edges LE of the front panel F and the back panel R, respectively.

The leg elastic member 37 has a first portion 37a that follows the leg edge LE, and a second portion 37b that is continuous with the first portion 37a and extends toward the center in the lateral direction Y. The first portion 37a is a curved portion that follows the leg edge LE, and the second portion 37b is a portion that follows the lateral direction Y (see Figures 1 and 2). In this embodiment, the second portion 37b overlaps with the absorber 4 in a plan view.
The outer casing 3 has a pre-cut region 3R between the second portions 37b, 37b of the left and right leg elastic members 37. The pre-cut region 3R is the region sandwiched between the lateral Y-inward ends of the second portions 37b of the pair of left and right leg elastic members 37, and the region where the lateral Y-inward ends are located coincides with the position in the vertical X direction (see Figures 1 and 6).
In this embodiment, the pre-cut region 3R does not exhibit elasticity in the lateral direction Y because the leg elastic member 37 is absent. Alternatively, the pre-cut region 3R may be modified such that the leg elastic member 37 is finely divided to prevent elastic stretching.

The outer garment 3 of this embodiment has a front stretchable region FE on the front panel F that stretches along the horizontal direction Y, and a rear stretchable region RE on the back panel R that stretches along the same direction Y. These front stretchable region FE and rear stretchable region RE are collectively referred to as the "stretchable region." In this embodiment, these "stretchable regions" are composed of a stretchable sheet, which is one of the multiple sheets constituting the outer garment 3. The stretchable region in this embodiment is composed of a front outer layer sheet 31a and a rear outer layer sheet 31b. Because the outer garment 3 is equipped with a stretchable sheet, the diaper 1 fits snugly to the body when worn, giving it an appearance similar to underwear.

From the viewpoint of further improving the fit of diaper 1, the break elongation of the stretchable sheet is preferably 30% to 200%, more preferably 50% to 180%. The method for measuring break elongation will be described later.

Preferably, the stretchable sheets used in the present invention include (1) a stretchable nonwoven fabric in which an elastic fiber layer has an expandable fiber layer integrated on both or one side of an elastic fiber layer, (2) a stretchable nonwoven fabric in which an expandable fiber layer has an expandable fiber layer integrated on both or one side of a net-like elastic sheet, (3) a stretchable nonwoven fabric in which an elastic sheet made of an elastic film has an expandable fiber layer integrated on both or one side of an elastic sheet, and (4) a stretchable nonwoven fabric in which a large number of elastic filaments arranged to extend in one direction without intersecting each other are integrated into an expandable fiber layer.
The term "stretchable fiber layer" as used herein includes not only fiber layers that are stretchable before integration with an elastic material, but also fiber layers that have been made stretchable by machining or other means after integration with an elastic material.
Methods for integrating an elastic fiber layer with an extendable fiber layer include, for example, laminating them and entangling the fibers by water flow entanglement or air passage, or joining them by heat embossing, adhesive, or ultrasound. Elastic fibers can be made from thermoplastic elastomers such as styrene elastomers, polyolefin elastomers, polyester elastomers, or polyurethane elastomers, or from elastic resins such as rubber. Non-elastic fibers can be made from thermoplastic resins.

The stretchable nonwoven fabric described in (4) above includes, for example, a fabric having a structure in which thread-like elastic filaments are sandwiched between stretchable fiber layers mainly composed of inelastic fibers, thereby integrating them. Such a stretchable nonwoven fabric comprises two fiber sheets as fiber layers and elastic filaments interposed between these two sheets. This stretchable nonwoven fabric can be manufactured, for example, according to the method described in Japanese Patent Application Publication No. 2009-61743.

In the stretchable nonwoven fabric described in (4) above, both fiber sheets are stretchable. These two fiber sheets are stretchable in the same direction as the elastic filaments. The stretchable form includes (a) a form in which the constituent fibers of the sheet itself stretch, and (b) a form in which, even if the constituent fibers themselves do not stretch, the sheet as a whole stretches due to mechanical processing, such as the separation of fibers that were bonded at intersections, structural changes in the three-dimensional structure formed by multiple fibers due to bonding between fibers, or the tearing of constituent fibers. Examples of mechanical processing in (b) above include heat treatment, stretching between rolls, stretching by meshing with teeth or gears, and tensile stretching by a tenter.

In the stretchable nonwoven fabric described in (4) above, the elastic filaments can be formed by stretching an elastic resin in a melted or softened state. Multiple elastic filaments are arranged continuously in one direction, extending in that direction without intersecting each other. The elastic filaments are joined to two fiber sheets in a substantially non-stretched state. This joining is achieved by fusing the constituent fibers (non-elastic fibers) of the two fiber sheets to the elastic filaments while they are embedded within them, and is not done using an adhesive such as a hot-melt adhesive. Therefore, there is no adhesive between the two fiber sheets (stretchable fiber layers mainly composed of non-elastic fibers) and the elastic filaments joined thereto.

The two fiber sheets constituting the stretchable nonwoven fabric described in (4) above can each be various types of nonwoven fabrics, such as air-through nonwoven fabric, heat-rolled nonwoven fabric, spunlace nonwoven fabric, spunbond nonwoven fabric, or meltblown nonwoven fabric. The two fiber sheets may be of the same type or different types. Here, "sheets of the same type" 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 sheets, etc., are all the same. If at least one of these is different, they are "different types of sheets." The elastic filament is made from materials such as thermoplastic elastomer or rubber. In particular, when thermoplastic elastomer is used as a raw material, melt spinning using an extruder is possible, similar to ordinary thermoplastic resins, and the elastic filament obtained in this way is easy to heat-seal, making it suitable for stretchable nonwoven fabrics.
From the viewpoint of further improving the fit to the wearer's body, it is preferable that the stretchable region is formed of the stretchable nonwoven fabric described in (4) above. In this case, the stretchable nonwoven fabric forming the stretchable region has elastic filaments whose extension direction coincides with the transverse direction Y.

In this embodiment, the front outer layer sheet 31a extends inward in the longitudinal direction X from the inward end of the ventral portion A, reaching the end of the ventral portion A on the crotch side C. Similarly, the rear outer layer sheet 31b in this embodiment extends inward in the longitudinal direction X from the inward end of the dorsal portion B, reaching the end of the dorsal portion B on the crotch side C. As a result, in the longitudinal direction X, the front stretchable region FE extends to the end of the ventral portion A on the crotch side C, and the rear stretchable region RE extends to the end of the dorsal portion B on the crotch side C (see Figure 2).

The outer casing 3 has a non-stretchable region NE located between the front stretchable region FE and the rear stretchable region RE. In this embodiment, the non-stretchable region NE is a region in the outer casing 3 that does not stretch in the lateral direction Y, and is a region where no stretchable members such as the aforementioned stretchable sheet are provided. In this embodiment, only a non-stretchable sheet is provided in the non-stretchable region NE. Specifically, the non-stretchable region NE is a region where the outer layer sheet 31 is not provided, and only the inner layer sheet 33, which is a non-stretchable sheet, is provided (see Figure 2).
In this embodiment, the non-stretchable region NE is located in the central part of the vertical direction X in the front body F and back body R, and is sandwiched between the front stretchable region FE and the back stretchable region RE in the vertical direction X.

A non-stretchable sheet is a sheet that is substantially non-stretchable in a certain direction. In this embodiment, it is preferably a sheet that is non-stretchable at least in the transverse direction Y, and preferably a sheet that is non-stretchable in both the longitudinal direction X and the transverse direction Y. A non-stretchable sheet means that even when a tensile force is applied to the sheet in that direction, the sheet hardly stretches. For example, if a sheet sample measuring 15 cm in length and 5 cm in width is pulled in the longitudinal direction using a material tensile testing machine such as Tensilon, and the elongation at break is 10% or less, then the sample is substantially non-stretchable in the longitudinal direction. This elongation at break can be calculated as (length of the sample at break - original length of the sample) / (original length of the sample) × 100.

In this embodiment, the absorber 4 is positioned to bridge the gap between the front stretchable region FE and the rear stretchable region RE via the non-stretchable region NE (see Figure 2).
The absorbent core 40 has a lower core 45 and an upper core 41 positioned on the skin-facing side of the lower core 45 (see Figures 3 and 4). In other words, the absorbent core 40 has a laminated structure in which the upper core 41 and the lower core 45 are stacked.

The lower core 45 of this embodiment, like the absorber 4, has a shape that is elongated in the vertical direction X, and has an hourglass shape in which both side edges in the center of the vertical direction X are constricted inward in the horizontal direction Y. The lower core 45 has a lower low-rigidity portion 46 that extends in the vertical direction X, and a lower high-rigidity portion 47 that is more rigid than the lower low-rigidity portion 46 (see Figures 1 and 2). The lower low-rigidity portion 46 is a part of the lower core 45 that is less rigid than the lower high-rigidity portion 47, which is the other part. For example, the lower low-rigidity portion 46 is a low-basis-weight portion where the basis weight of the core-forming material forming the lower core 45 is lower than that of other parts, or a part where the core-forming material is missing. The latter includes a slit (through hole) that penetrates the lower core 45, or a bottomed recess.
In this embodiment, the lower high-rigidity section 47 surrounds the lower low-rigidity section 46 and forms the outer edge (contour) of the lower core 45. The lower high-rigidity section 47 in this embodiment has a higher basis weight of the core-forming material than the lower low-rigidity section 46.

The upper core 41 of this embodiment, like the lower core 45, has a shape that is elongated in the vertical direction X, and is positioned in the central part of the lower core 45 in the vertical direction X. The entire upper core 41 is positioned within the non-stretchable region NE. That is, the upper core 41 has its dorsal side B end 41b and its ventral side A end 41a in the vertical direction X located within the non-stretchable region NE.
The upper core 41 has an upper low-rigidity portion 42 extending in the vertical direction X, and an upper high-rigidity portion 43 that is more rigid than the upper low-rigidity portion 42 (see Figures 4 and 5). The upper low-rigidity portion 42 is a low-basis-weight portion where the basis weight of the core-forming material forming the upper core 41 is lower than that of other portions, or a portion where the core-forming material is missing, and the same explanation as for the lower low-rigidity portion 46 described above applies.
In this embodiment, the upper high-rigidity portion 43 surrounds the upper low-rigidity portion 42 and forms the outer edge (contour) of the upper core 41. The upper high-rigidity portion 43 in this embodiment has a higher basis weight of the core-forming material than the upper low-rigidity portion 42.
The upper high-rigidity section 43 has end high-rigidity sections 44, 44 located on both sides of the upper low-rigidity section 42 in the vertical direction X. That is, the end high-rigidity sections 44, 44 are located outward in the vertical direction X from the upper low-rigidity section 42 (see Figures 1 and 2).

In this embodiment, the lower core 45 has both ends in the vertical direction X located in the expandable region, and the constricted central portion in the vertical direction X is located in the non-expandable region NE (see Figure 2).
In this embodiment, the lower low-rigidity portion 46 extends from the upper core 41 in both the ventral side A and the dorsal side B in the longitudinal direction X. That is, the lower low-rigidity portion 46 has a longer length in the longitudinal direction X than the upper core 41. In this embodiment, the entire length of the lower low-rigidity portion 46 is contained within the non-stretchable region NE. Alternatively, the lower low-rigidity portion 46 may be located in the non-stretchable region NE, and its end in the longitudinal direction X may extend to either or both of the front stretchable region FE and the rear stretchable region RE.

From the viewpoint of further improving the fit and absorption performance of the absorbent 4, it is preferable that at least one of the upper low-rigidity portion 42 and the lower low-rigidity portion 46 is a slit (through hole), and it is more preferable that both of these low-rigidity portions 42 and 46 are slits (through holes). Such a configuration is preferable in that it increases the flexibility of the absorbent core 40, improves the fit of the absorbent 4, and also improves liquid diffusion.
In this embodiment, the upper low-rigidity portion 42 and the lower low-rigidity portion 46 are slits extending in the vertical direction X, and the basis weight of the material forming the absorbent core 40 (lower core 45) is 0 g/ ^m² .

In the pre-cut region 3R, the high-rigidity end portion 44 and the low-rigidity lower portion 46 of the upper high-rigidity portion 43 overlap in a plan view. More specifically, in a plan view, the high-rigidity end portion 44 and the low-rigidity lower portion 46 overlap at least partially within the pre-cut region 3R (see Figure 6). In this embodiment, the diaper 1 has the low-rigidity lower portion 46 overlapping so as to traverse the pre-cut region 3R longitudinally, and the high-rigidity end portion 44 overlapping the entire pre-cut region 3R.

The absorbent core 40 of this embodiment has an upper core 41 positioned on the skin-facing surface of the lower core 45. As such, the upper core 41 is a protruding portion that faces the skin, and when worn, the upper core 41 fits snugly against the wearer's groin area. Furthermore, because the absorbent core 40 has a two-tiered structure of upper and lower layers, it provides excellent absorption performance.
In this embodiment, the diaper 1 has a high-rigidity end portion 44 and a low-rigidity lower portion 46 overlapping in the pre-cut region 3R. This makes it easy for the lower core 45 to deform into a mountain fold starting from the low-rigidity lower portion 46, and consequently, the high-rigidity end portion 44 curves appropriately towards the skin (see Figure 7). As a result, the upper core 41 takes on a shape that easily adheres to the wearer's crotch area, resulting in a good fit. Furthermore, because the upper core 41 fits well, it can efficiently absorb excretory fluids such as urine, resulting in excellent absorption performance. Since the entire upper core 41 is located within the non-stretch region NE, unintended deformation due to stretching of the stretch region is unlikely to occur. As a result, the absorbent core 40 can be kept in a state that conforms to the wearer's body, resulting in a superior wearing comfort.

From the viewpoint of further improving the fit of the upper core 41 and enhancing the effects described above, it is preferable that the diaper 1 has the following configuration.
The width W10 of the pre-cut area 3R (see Figure 6) is preferably 95% or more, more preferably 100% or more, preferably 120% or less, more preferably 110% or less, preferably 95% to 120%, more preferably 100% to 110%, relative to the width W3 of the upper core 41 (see Figure 1).
If the width W3 of the upper core 41 differs in the vertical direction X, the width shall be the maximum width.
If the width W10 of the pre-cut area 3R differs in the vertical direction X, the width shall be the maximum width.

The width W10 of the pre-cut area 3R (see Figure 6) is preferably 35 mm or more, more preferably 40 mm or more, also preferably 60 mm or less, more preferably 70 mm or less, also preferably 35 mm or more and 70 mm or less, more preferably 40 mm or more and 60 mm or less.
The length L10 in the vertical direction X of the pre-cut area 3R (see Figure 6) is preferably 5 mm or more, more preferably 10 mm or more, also preferably 30 mm or less, more preferably 20 mm or less, also preferably 5 mm to 30 mm, more preferably 10 mm to 20 mm.
The width W1 (see Figure 2) of the lower low-rigidity section 46 is preferably 5 mm or more, more preferably 8 mm or more, also preferably 20 mm or less, more preferably 15 mm or less, also preferably 5 mm to 20 mm, more preferably 8 mm to 15 mm.

From the viewpoint of further improving the fit of the absorbent core 40, the width W3 of the upper core 41 (see Figure 1) is preferably 40% or more, more preferably 50% or more, preferably 80% or less, more preferably 70% or less, preferably 40% to 80%, and more preferably 50% to 70% of the width W5 of the lower core 45 in the non-stretchable region NE (see Figure 1).
If the width W5 of the lower core 45 differs in the vertical direction X, the width shall be the minimum width.

In this embodiment, the leg elastic member 37 overlaps with the lower high-rigidity portion 47 of the lower core 45 in a plan view (see Figure 6). In other words, the second portion 37b of the leg elastic member 37 extends inward in the lateral direction Y of the lower core 45, and the lateral inward end of the second portion 37b overlaps with the lower core 45. This allows the absorbent core 40 to be deformed appropriately, further improving the fit.
In this embodiment, when the lower core 45 has a constricted portion, it is preferable that the second portion 37b terminates within the maximum width of the lower core 45. If the maximum width of the lower core 45 differs between the dorsal and ventral sides of the constricted portion, it is preferable that the second portion 37b terminates within the narrower maximum width.
From the viewpoint of further improving fit, the distance L9 (hereinafter also referred to as "overlap distance L9") between the inner end of the second portion 37b in the lateral direction Y and the position in the lateral direction Y corresponding to the maximum width of the lower core 45 is preferably 10 mm or more and 60 mm or less, more preferably 20 mm or more and 50 mm or less. The position in the lateral direction Y corresponding to the maximum width is the position in the lateral direction Y of the side edge of the core 45 along the vertical direction X at the position where the lower core 45 is at its maximum width, and the distance (length in the lateral direction Y) between a virtual straight line aL (see Figure 6) extending in the vertical direction X through the position in the lateral direction Y of the side edge and the inner end of the second portion 37b in the lateral direction Y is the overlap distance L9 (see Figure 6).

The upper low-rigidity section 42 and the lower low-rigidity section 46 are preferably positioned in the center of the diaper 1 in the lateral direction Y (see Figures 1 and 2). In this case, when the entire length of the diaper 1 in the lateral direction Y is divided into three equal regions, the lower low-rigidity section 46 is preferably located in the central region. With this configuration, the central portion of the absorbent core 40 easily fits along the wearer's urinary excretion area when worn (see Figure 7).

As mentioned above, the entire upper core 41 is located within the non-stretchable region NE, but it is also preferable that the entire lower low-rigidity portion 46 is located within the non-stretchable region NE. This configuration prevents the absorbent core 40 from excessively digging into the body or the leg edge portion LE of the back panel R from excessively digging into the buttocks due to the wearer's movements. Furthermore, by locating the easily deformable low-rigidity portion within the non-stretchable region NE, deformation and displacement of the absorbent core 40 due to the stretching and contracting of the stretchable region can be suppressed. In this embodiment, the entire length of the lower low-rigidity portion 46 in the vertical direction X is contained within the non-stretchable region NE.

From the viewpoint of more reliably achieving the above effects, the length L5 of the lower low-rigidity portion 46 in the vertical direction X is preferably 80% or more, more preferably 90% or more, of the length L8 of the non-stretchable region NE in the vertical direction X (see Figure 2).
The length L5 of the lower low-rigidity portion 46 in the vertical direction X (see Figure 2) is preferably 200 mm or more, more preferably 250 mm or more, also preferably 350 mm or less, more preferably 300 mm or less, also preferably 200 mm to 350 mm, and more preferably 250 mm to 300 mm.

From the viewpoint of further improving fit, the upper core 41 preferably has the following configuration.
The length L3 of the upper low-rigidity portion 42 in the vertical direction X (see Figure 2) is preferably 25% or more, more preferably 30% or more, preferably 90% or less, more preferably 80% or less, preferably 25% to 90%, and more preferably 30% to 80%.
The width W7 of the upper low-rigidity portion 42 (see Figure 1) is preferably 10% or more, more preferably 15% or more, preferably 40% or less, more preferably 30% or less, preferably 10% to 40%, and more preferably 15% to 30% of the width W3 of the upper core 41 (see Figure 1).
The length L3 of the upper low-rigidity portion 42 in the vertical direction X (see Figure 2) is preferably 60 mm or more, more preferably 70 mm or more, also preferably 210 mm or less, more preferably 180 mm or less, also preferably 60 mm or more and 210 mm or less, more preferably 70 mm or more and 180 mm or less.
The width W7 of the upper low-rigidity portion 42 (see Figure 1) is preferably 5 mm or more, more preferably 8 mm or more, also preferably 20 mm or less, more preferably 15 mm or less, also preferably 5 mm to 20 mm, more preferably 8 mm to 15 mm.

From the viewpoint of further improving the fit to the body and the liquid diffusion in the absorbent material 4, it is preferable that the lower low-rigidity portion 46 and the upper low-rigidity portion 42 overlap at least partially in a plan view (see Figures 1 and 2). With this configuration, the low-rigidity portions overlap, which increases the conformity to the wearer's body and improves the wearing comfort.
In this embodiment, the absorbent core 40 has an upper low-rigidity portion 42 that overlaps entirely with the lower low-rigidity portion 46.
From the viewpoint of further improving the above effects, the length in the vertical direction X of the portion where the lower low-rigidity portion 46 and the upper low-rigidity portion 42 overlap is preferably 80% or more, more preferably 90% or more, preferably 100% or less, more preferably 98% or less, preferably 80% to 100%, and more preferably 90% to 98% of the length L3 in the vertical direction X of the upper low-rigidity portion 42.

Figure 8 shows the arrangement of the joints 14 and 16 between the outer casing 3 and the absorbent body 5. For ease of explanation, the stretchable and non-stretchable regions NE are omitted from Figure 8. As mentioned above, the outer casing 3 and the absorbent body 5 are joined by known joining means such as adhesives. That is, the diaper 1 has joints 14 and 16 that join the outer casing 3 and the absorbent body 5 (Figure 8). The diaper 1 of this embodiment has a pair of vertical joints 14 extending in the vertical direction X and a pair of horizontal joints 16 extending in the horizontal direction Y. The vertical joints 14 are arranged on both sides of the absorbent body 5 along the vertical direction X on the non-skin-facing surface (leak-proof sheet 13) of the absorbent body 5. The horizontal joints 16 are arranged on both sides of the absorbent body 5 along the vertical direction X on the non-skin-facing surface (leak-proof sheet 13) of the absorbent body 5, i.e., the end on the ventral side A and the end on the dorsal side B.

From the viewpoint of further improving the wearing comfort, it is preferable that, in a plan view, at least the lower low-rigidity portion 46 does not overlap with the joint portions 14 and 16, and it is even more preferable that the upper low-rigidity portion 42 and the lower low-rigidity portion 46 each do not overlap with the joint portions 14 and 16. This makes it difficult for the expansion and contraction of the stretchable region to be transmitted to the lower low-rigidity portion 46 via the joint portions 14 and 16, thereby suppressing the shifting of the absorbent core 40 or excessive digging into the wearer's body.
In this embodiment, the vertical joint portion 14 and the horizontal joint portion 16 are positioned to surround the upper low-rigidity portion 42 and the lower low-rigidity portion 46, and not to overlap with these low-rigidity portions 42 and 46 (see Figure 8).

From the viewpoint of achieving a better balance between fit and absorption performance, the basis weight of the upper core 41 is preferably 100 g/ ^m² or more, more preferably 130 g/ ^m² or more, also preferably 200 g/ ^m² or less, more preferably 180 g/ ^m² or less, also preferably 100 g/ ^m² or more and 200 g/ ^m² or less, more preferably 130 g/ ^m² or more and 180 g/ ^m² or less.
From the same viewpoint as above, the basis weight of the lower core 45 is preferably 80 g/ ^m² or more, more preferably 90 g/ ^m² or more, also preferably 130 g/ ^m² or less, more preferably 120 g/ ^m² or less, also preferably 80 g/ ^m² or more and 130 g/ ^m² or less, more preferably 90 g/ ^m² or more and 120 g/ ^m² or less.
The basis weights of these upper core 41 and lower core 45 are the basis weights of the high-rigidity sections 43 and 47.

If either or both of the upper low-rigidity portion 42 and the lower low-rigidity portion 46 are low-basis-weight portions where core-forming material for the upper core 41 or lower core 45 exists, from the viewpoint of ensuring a more reliable fit of the absorbent core 40, the basis weight of the upper core 41 or lower core 45 is preferably within the following range.
The upper core 41 has a basis weight difference of preferably 50 g/m² or more, more preferably 70 g/ ^m² or more, and also preferably 200 g/ ^m² or less, more preferably 180 g/ ^m² or less, and also preferably 50 g/ ^m² or more and 200 g/ ^m² or less, ^and more preferably 70 g/ ^m² or more and 180 g/ ^m² or less.
The lower core 45 has a difference between the basis weight of the lower low-rigidity portion 46 and the basis weight of the other portions, preferably 30 g/ ^m² or more, more preferably 50 g/ ^m² or more, also preferably 180 g/ ^m² or less, more preferably 150 g/ ^m² or less, also preferably 30 g/ ^m² or more and 180 g/ ^m² or less, more preferably 50 g/ ^m² or more and 150 g/ ^m² or less.

From the viewpoint of fitting the outer body 3 to the body and obtaining a more underwear-like appearance, the elongation rate of the stretchable area is preferably 105% or more, more preferably 110% or more, also preferably 130% or less, more preferably 125% or less, also preferably 105% to 130%, more preferably 110% to 125%.
The elongation rate of the stretchable area is measured by the following method.

[Method for measuring elongation rate]
Since the stretchable region is composed of sheet material such as an expandable sheet, the sheet material exhibiting stretchability in the outer casing is to be measured. First, with the diaper in its natural state, two marks are made on the sheet material constituting the stretchable region of the outer casing, 50 mm apart in the stretching direction (lateral direction Y). With this sheet material stretched to its maximum extent, the distance between the two marks is measured as the stretched distance (mm). Then, the stretching rate of the stretchable region is calculated using the following formula (1).
Elongation rate of the stretchable area (%) = [Elongation distance (mm) / 50 (mm)] × 100 ... (1)

Next, the materials used to form each part of diaper 1 will be described. For the inner layer sheet 33 and the fixing sheet 35, various materials conventionally used as outer coverings in this type of absorbent article can be used without particular limitation. For example, as the inner layer sheet 33, nonwoven fabrics manufactured using various methods such as spunbond nonwoven fabric, air-through nonwoven fabric, and needle-punched nonwoven fabric can be used.

The elastic members 32, 37, 48, and 61 of the leg elastic members are preferably made from stretchable materials such as natural rubber, polyurethane resin, foamed urethane resin, and hot-melt stretchable material, formed into thread-like (thread-like rubber) or strip-like (flat rubber) shapes.
Various nonwoven fabrics and perforated films can be used as the surface sheet 12, and resin films or laminates of resin films and nonwoven fabrics can be used as the leak-proof sheet 13.

The absorbent core 40 of the absorbent body 4 is formed from core-forming materials such as hydrophilic fibers including pulp and cellulose, and water-absorbent polymers. The absorbent core 40 consists of, for example, a stack of hydrophilic fibers, a mixed stack of hydrophilic fibers and water-absorbent polymers, a deposit of water-absorbent polymers, or a laminated structure in which water-absorbent polymers are supported between two absorbent sheets.
For the core wrap sheet 49, for example, a thin paper made of hydrophilic fibers or a nonwoven fabric that is permeable to liquids can be used.

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.
For example, in the above-described embodiment, the diaper 1 had the leg elastic member 37 only on the front panel F, but it may also have the leg elastic member 37 on both the front panel F and the back panel R.
Furthermore, although the diaper 1 in the above-described embodiment had an hourglass-shaped lower core 45, the side edges of the lower core 45 do not necessarily have to be constricted inward in the lateral direction Y, and the side edges may be parallel to the vertical direction X.

1. Pant-type disposable diapers (diapers)
3 Outer body 4 Absorbent body 5 Absorbent main body 6 Leak-proof cuff 12 Surface sheet 13 Leak-proof sheet 31 Outer layer sheet 32 Waist elastic member 33 Inner layer sheet 34 End fixing sheet 35 Fixing sheet 37 Leg elastic member 40 Absorbent core 41 Upper core 42 Upper low rigidity part 43 Upper high rigidity part 45 Lower core 46 Lower low rigidity part 47 Lower high rigidity part 48 Intermediate elastic member 49 Core wrap sheet 60 Cuff forming sheet 61 Cuff elastic member A Ventral part B Back part C Crotch area F Front body R Back body FE Front stretch area RE Back stretch area NE Non-stretch area X Vertical Y Horizontal

Claims (8)

An absorbent article in the form of pants, comprising an absorbent body having an absorbent core, an absorbent body having an absorbent core, and an outer casing disposed on the non-skin-facing side of the absorbent body, having a longitudinal direction extending from the ventral direction through the crotch to the back direction and a transverse direction perpendicular to the longitudinal direction, and divided by the center of the longitudinal direction into a front body that is disposed on the ventral side of the wearer when worn and a back body that is disposed on the back side of the wearer, and having a waist opening and a pair of leg openings,
The exterior body has a front stretchable region on the front body that stretches along the lateral direction, a rear stretchable region on the back body that stretches along the lateral direction, and a non-stretchable region located between the front stretchable region and the rear stretchable region.
The absorbent core comprises a lower core and an upper core positioned on the skin-facing side of the lower core, wherein the entire upper core is located within the non-stretchable region.
The lower core has a lower low-rigidity portion extending in the vertical direction and a lower high-rigidity portion that has higher rigidity than the lower low-rigidity portion.
The upper core has an upper low-rigidity portion extending in the vertical direction and an upper high-rigidity portion that has higher rigidity than the upper low-rigidity portion.
The exterior body has a leg elastic member that forms a leg gather, and the leg elastic member has a first portion that runs along the periphery of the leg opening, and a second portion that is continuous with the first portion and extends toward the lateral center.
The exterior body has a pre-cut region between the second portions of the left and right leg elastic members in which no stretching or contracting occurs.
In the pre-cut region, the absorbent article has an end high-rigidity portion located vertically outward from the upper low-rigidity portion in the upper high-rigidity portion and the lower low-rigidity portion overlap in a plan view. The absorbent article according to claim 1, wherein the upper low-rigidity portion and the lower low-rigidity portion are positioned at the lateral center of the absorbent article. The absorbent article according to claim 1 or 2, wherein at least one of the upper low-rigidity portion and the lower low-rigidity portion is a slit. The absorbent article according to claim 3, wherein both the upper low-rigidity portion and the lower low-rigidity portion are slits. It has a joint that connects the outer casing and the absorbent body,
The absorbent article according to claim 1 or 2 , wherein, in a plan view, at least the lower low-rigidity portion does not overlap with the joint portion. The absorbent article according to claim 1 or 2 , wherein the entire lower low-rigidity portion is located within the non-stretchable region. The absorbent article according to claim 1 or 2 , wherein the front stretchable region and the rear stretchable region are made of a stretchable sheet having elasticity in the lateral direction. The absorbent article according to claim 1 or 2 , wherein the upper low-rigidity portion and the lower low-rigidity portion overlap at least partially in a plan view.