Pants-type disposable diaper

Abstract

To provide a pants-type disposable diaper having an excellent fitting property while suppressing slipping and digging.SOLUTION: A pants-type disposable diaper 1 comprises an absorbent body 5 including an absorbent core 40, and an outer wrapper 3 disposed on a non-skin-facing surface side of the absorbent body 5. The outer wrapper 3 includes stretchable areas FE and RE with stretchability, respectively provided along a lateral direction Y in a front body F and a back body R, and a non-stretchable area NE located between the stretchable areas. The absorbent core 40 includes a lower-layer core 45 and an upper-layer core 41, and the lower-layer core 45 has a lower-layer low rigidity part 46 extending in a longitudinal direction X. An entire body of the upper-layer core 41 is disposed in the non-stretchable area NE. The lower-layer low rigidity part 46 is so configured that in plan view, at least an end on a dorsal part B side is in the non-stretchable area NE and extends to the dorsal part B side beyond an end 41b of the upper core 41 on the dorsal part B side.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a pants-type disposable diaper. [Background technology]

[0002] Pants-type disposable diapers generally include an absorbent body including an absorbent core that serves as a main liquid absorbing portion. It is known that the absorbent core is provided with openings and low basis weight portions in consideration of wearing comfort, absorption performance, and the like. Pants-type disposable diapers have a waist opening and a pair of leg openings, and are worn by placing the wearer's legs through the leg openings and arranging the waist opening around the waist. In other words, since they are worn like underwear, a stretchable sheet may be used for the sheet material forming the outer surface of the disposable diaper so that the disposable diaper fits the body.

[0003] For example, the present applicant has previously proposed a pants-type absorbent article comprising an outer body having an elastic outer sheet and an absorbent core having an opening formed so as to extend in the vertical direction, the opening having an opening on the skin-facing surface or the non-skin-facing surface (Patent Document 1).

[0004] Patent Document 2 discloses a pants-type absorbent article comprising a pair of belt portions having elasticated regions that stretch laterally, and an absorbent core in which a low basis weight region and a lattice-shaped low basis weight region are formed along the longitudinal direction, and in which part of the elasticated region in the rear belt portion crosses the low basis weight region along the longitudinal direction. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent No. 6559940 [Patent Document 2] Patent No. 6982973 Summary of the Invention [Problem to be solved by the invention]

[0006] The techniques of Patent Documents 1 and 2 reduce the rigidity of the absorbent core by providing an opening or a low basis weight portion in the absorbent core. This configuration is effective in fitting the absorbent core to the wearer's body. In addition, by using a stretchable sheet as a component arranged on the outer surface side of the disposable diaper, the fit to the wearer's body is improved and an underwear-like silhouette is obtained. However, when a disposable diaper is equipped with an absorbent core having an opening or a low basis weight portion and a stretchable sheet, there is a risk that the disposable diaper may shift in the wearing position due to the stretching of the stretchable sheet or the wearer's movement, or that the absorbent core may dig into the body too much. Patent Documents 1 and 2 do not disclose a technique that can suppress the shifting or digging in.

[0007] The present invention relates to a pants-type disposable diaper which is excellent in fit while preventing slippage and digging in. [Means for solving the problem]

[0008] The present invention relates to a pants-type disposable diaper having a ventral side portion arranged on the ventral side of a wearer, a dorsal side portion arranged on the dorsal side of the wearer, and a crotch portion located between the ventral side portion and the dorsal side portion, and having a vertical direction extending from the ventral side portion via the crotch portion to the dorsal side portion and a horizontal direction perpendicular to the vertical direction, the diaper comprising an absorbent body including an absorbent core, and an outer body arranged on the non-skin-facing side of the absorbent body, the diaper having a waist opening and a pair of leg openings, and divided, with the center in the vertical direction as the boundary, into a front body portion arranged on the ventral side of the wearer and a rear body portion arranged on the dorsal side of the wearer when worn. In one embodiment, it is preferable that the outer body has a front stretchable region in the front body that is stretchable along the horizontal direction, a rear stretchable region in the back body that is stretchable along the horizontal direction, and a non-stretchable region located between the front stretchable region and the rear stretchable region. In one embodiment, the absorbent core has a lower layer core and an upper layer core arranged on the skin-facing side of the lower layer core, and it is preferable that the lower layer core has a lower layer low stiffness portion extending in the vertical direction. In one embodiment, the upper core is entirely disposed within the non-elastic region, In one embodiment, it is preferable that, when viewed in a plane, at least the end portion on the rear side of the lower layer low rigidity portion is present in the non-elastic region and extends further toward the rear side than the end portion on the rear side of the upper layer core. Effect of the Invention

[0009] The pants-type disposable diaper of the present invention is excellent in fit while preventing slippage and digging in. [Brief description of the drawings]

[0010] [Figure 1] FIG. 1 is a view showing one embodiment of a pants-type disposable diaper of the present invention, and is a developed plan view showing a schematic view of the skin-facing surface side of the diaper in an unfolded and stretched state. [Diagram 2] FIG. 2 is a developed plan view illustrating a schematic view of the non-skin-facing side of the disposable diaper illustrated in FIG. [Diagram 3] FIG. 3 is an exploded perspective view of the disposable diaper shown in FIG. [Figure 4] FIG. 4 is a cross-sectional view taken along line II-II in FIG. [Diagram 5] FIG. 5 is a cross-sectional view taken along line III-III in FIG. [Figure 6] FIG. 6 is a rear view showing the diaper shown in FIG. 1 in a worn state. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will now be described based on preferred embodiments with reference to the drawings. Figures 1 to 6 show one embodiment of a pants-type disposable diaper 1 (hereinafter simply referred to as "diaper 1") of the present invention. As shown in Figures 1 and 2, the diaper 1 has a ventral portion A arranged on the ventral side of the wearer when worn, a dorsal portion B arranged on the dorsal side of the wearer, and a crotch portion C located between the ventral portion A and the dorsal portion B. The crotch portion C is a portion arranged in the crotch area of ​​the wearer when the diaper 1 is worn. The ventral portion A is a portion arranged on the ventral side, i.e., in front of the wearer, of the crotch portion C when the diaper 1 is worn. The dorsal portion B is a portion arranged on the dorsal side, i.e., behind the wearer, of the crotch portion C when the diaper 1 is worn. As shown in Figures 1 and 2, the diaper 1 has a longitudinal direction X corresponding to the front-to-back direction of a wearer and a transverse direction Y perpendicular thereto. In this specification, the "front-to-back direction of a wearer" refers to a direction extending from the wearer's abdominal side through the crotch region to the back side. The diaper 1 extends in the longitudinal direction X from the abdominal region A through the crotch region C to the back region B.

[0012] As shown in Figures 1 and 2, the diaper 1 is divided into a front body F, which is disposed in front of the wearer (belly side) when worn, and a rear body R, which is disposed on the wearer's back (rear side), with the longitudinal center (longitudinal centerline CLx) as the boundary. The longitudinal centerline CLx is an imaginary line extending in the lateral direction Y, dividing the diaper 1 in an unfolded and stretched state as shown in Figures 1 and 2 in half in the longitudinal direction X. The "unfolded and stretched state" of the diaper 1 refers to a state in which the diaper 1 is separated at the side seal portions described below to be unfolded, and the elastic members of each portion of the diaper 1 in the unfolded state are stretched to the designed dimensions (the same dimensions as when the diaper 1 is unfolded flat without any influence of the elastic members). In this specification, unless otherwise specified, each dimension of the diaper 1 (e.g., the absorbent core 40), such as the length (width) in the longitudinal direction X or the lateral direction Y, refers to the dimension (design dimension) when the elastic member of each part is stretched and each member is stretched.

[0013] The diaper 1 comprises an absorbent body 5 having a liquid-retentive absorbent 4, and an exterior body 3 arranged on the non-skin-facing side of the absorbent body 5. The exterior body 3 has both side edge portions AS, BS along the longitudinal direction X in each of the ventral side portion A and the back side portion B joined to each other by a known joining means such as adhesive, heat sealing, ultrasonic sealing, etc. As a result, the diaper 1 has a pair of side seal portions (not shown) where the both side edge portions AS, BS are joined to each other, 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 legs pass.

[0014] In this specification, the "skin-facing side" refers to the side of the disposable diaper or its constituent members (e.g., the topsheet 12) that faces the wearer's skin when the disposable diaper is worn, i.e., the side relatively closer to the wearer's skin, and the "non-skin-facing side" refers to the side of the disposable diaper or its constituent members that faces the side opposite the skin side when the disposable diaper is worn, i.e., the side relatively farther from the wearer's skin. "When worn" here refers to the normal, proper wearing position, i.e., the state in which the absorbent article (disposable diaper) is maintained in the correct wearing position.

[0015] The absorbent main body 5 has a rectangular shape in a plan view, extends in the vertical direction X, and is disposed at the center of the exterior body 3 in the horizontal direction Y with its longitudinal direction coinciding with the vertical direction X of the diaper 1 in an unfolded and stretched state. The absorbent main body 5 is joined to the exterior body 3 by a known joining means such as an adhesive. In the absorbent main body 5 of this embodiment, the skin-facing surfaces of both ends in the longitudinal direction X are covered with end fixing sheets 34, 34 and fixed to the exterior body 3. The end fixing sheets 34 are joined to the exterior body 3 and the absorbent main body 5 by a known joining means such as an adhesive (see Figs. 1 and 3).

[0016] The absorbent body 5 comprises a liquid-permeable surface sheet 12 which forms the skin-facing side, a liquid-impermeable or poorly liquid-permeable or water-repellent leak-proof sheet 13 which forms the non-skin-facing side, and a liquid-retaining absorbent 4 arranged between the surface sheet and the leak-proof sheet, which are integrated together using known joining means such as an adhesive. As shown in Fig. 4, the absorbent body 4 of this embodiment is configured to include an absorbent core 40 and a core wrap sheet 49 that covers the surface of the absorbent core 40. The absorbent body 4 of this embodiment has the entire surface, including the skin-facing surface and the non-skin-facing surface, covered with the core wrap sheet 49. Alternatively, the skin-facing surface of the absorbent core 40 may be covered with the liquid-permeable core wrap sheet 49. The absorbent body 4 may not include the core wrap sheet 49. Details of the absorbent core 40 will be described later.

[0017] 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 horizontal direction Y. The intermediate elastic members 48 of this embodiment are disposed in a stretched state between the topsheet 12 and the leakproof sheet 13 on the outer side in the horizontal direction Y of the absorbent body 4. When the absorbent main body 5 includes an intermediate elastic member 48, the intermediate elastic member 48 may be disposed in a stretched state between the core wrap sheet 49 and the absorbent core 40, or may be disposed in a stretched state between the topsheet 12 and the absorbent core 40. The position of the intermediate elastic member 48 in the height direction Z is not particularly limited, and the position in the height direction Z may be different between the unfolded and stretched state of the diaper 1 and the natural state of the diaper 1. For example, the intermediate elastic member 48 may be located approximately in the center of the height of the absorbent body 4 in the natural state, or may be located on the non-skin-facing side of the center of the height of the absorbent body 4 in the unfolded and stretched state.

[0018] The diaper 1 of this embodiment has a pair of leakage-preventing cuffs 6, 6 made of a liquid-resistant or water-repellent and breathable sheet material on both left and right sides along the longitudinal direction X of the skin-facing surface of the absorbent main body 5 (see Figs. 1 and 4). The leakage-preventing cuffs 6 of this embodiment have a cuff-forming sheet 60 and a cuff elastic member 61, and the cuff elastic member 61 is arranged in a stretched state between the cuff-forming sheet 60 folded in half. The leakage-preventing cuffs 6 have free inner ends in the transverse direction Y and free outer ends in the transverse direction Y that are rolled up on the non-skin-facing side of the absorbent main body 5, i.e., the non-skin-facing side of the leakage-preventing sheet 13, and are fixed between the leakage-preventing sheet 13 and the exterior body 3 with an adhesive or the like. Near the free ends of the leakage-preventing cuffs 6, one or more thread-like cuff elastic members 61 extending in the longitudinal direction X are arranged in a stretched state (see Fig. 4). The leakage preventing cuffs 6 stand up at least at the crotch portion C as the cuff elastic members 61 arranged in a stretched state contract, thereby preventing the outflow of excreted liquids such as urine in the lateral direction Y outward. For ease of explanation, the leak-proof cuffs 6 are omitted from FIG.

[0019] The exterior body 3 forms the outer shape of the diaper 1, i.e., the outer shapes of the abdominal portion A, the crotch portion C, and the back portion B. As shown in Figs. 1 and 2, in a plan view in an unfolded and stretched state, the abdominal portion A and the back portion B of the exterior body 3 have a rectangular shape in which the length in the horizontal direction Y is longer than the vertical direction X, and in the crotch portion C, both side edges along the vertical direction X, i.e., a pair of leg edges LE, LE, form an hourglass shape narrowed inward in the horizontal direction Y. In the plan view in an unfolded and stretched state, the exterior body 3 of this embodiment has both side edges along the vertical direction X of the abdominal portion A and the back portion B protruding outward in the horizontal direction Y more than both side edges along the vertical direction X of the crotch portion C. In addition, the outer edge WE in the vertical direction X of the abdominal portion A and the outer edge WE in the vertical direction X of the back portion B of the exterior body 3 extend in the horizontal direction Y to form a waist opening in the diaper 1 having a side seal portion. That is, these outer edges in the longitudinal direction X form the peripheral edges WE of the waist opening.

[0020] The exterior body 3 is constructed by laminating a plurality of sheets. In the exterior body 3 of this embodiment, as shown in FIG. 3, an outer layer sheet 31, an inner layer sheet 33, and a fixing sheet 35 are laminated in this order from the non-skin facing side to the skin facing side. The outer layer sheet 31 forms the outer surface, i.e., the non-skin facing surface, of the diaper 1 at least in the abdominal side portion A and the back side portion B, and is divided into a front outer layer sheet 31a arranged in the front body portion F and a back outer layer sheet 31b arranged in the back body portion R, as shown in FIG. 1 and FIG. 3. The inner layer sheet 33 is arranged between the outer layer sheet 31 and the fixing sheet 35, and is fixed by bridging both the outer layer sheets 31a and 31b of the front body portion F and the back body portion R. The inner layer sheet 33 of this embodiment is continuous in the longitudinal direction X from the peripheral edge WE of the waist opening of the abdominal side portion A to the peripheral edge WE of the waist opening of the back side portion B. That is, the inner layer sheet 33 is continuous over the entire length of the diaper 1, and forms the outer surface of the diaper 1 between the front outer layer sheet 31a and the rear outer layer sheet 31b in the longitudinal direction X. The fixing sheet 35 is disposed on the skin-facing side of the inner layer sheet 33, and fixes leg elastic members 37 (described later) between the fixing sheet 35 and the inner layer sheet 33. These sheets 31, 33, 35 constituting the exterior body 3 are joined by a known joining means such as an adhesive.

[0021] In the exterior body 3 of this embodiment, the outer sheets 31a, 31b are folded back toward the skin-facing side along the peripheral edge WE of the waist opening (see FIG. 3). That is, the outer sheets 31a, 31b form the peripheral edge WE of the waist opening, and the folded-back portions of the sheets 31a, 31b extend inward in the longitudinal direction X from the peripheral edge WE. In the exterior body 3 of this embodiment, the inner layer sheet 33 is also folded back toward the skin-facing side along the peripheral edge WE of the waist opening, similar to the outer layer sheets 31a and 31b described above. In the vicinity of the peripheral edge WE of the waist opening of the exterior body 3 (not shown in FIG. 5), the folded back portions of the outer layer sheets 31a and 31b and the folded back portion of the inner layer sheet 33 overlap on the skin-facing side (see FIG. 5).

[0022] The exterior body 3 of this embodiment includes a plurality of thread-like or band-like elastic members 32 sandwiched and fixed in a stretched state in the folded-back portion of the inner layer sheet 33. Specifically, in the region of the ventral portion A and the back portion B that is arranged around the waist of the wearer, a plurality of elastic members 32 (hereinafter referred to as "waist elastic members 32") are arranged in a stretched state in the horizontal direction Y and at predetermined intervals in the vertical direction X. The waist elastic members 32 are arranged between both side edges along the vertical direction X of the ventral portion A and the back portion B, i.e., between the side seal portions in the horizontal direction Y, in a region that extends outward in the vertical direction X from the end edge of the absorbent main body 5 in the vertical direction X. Such a region is arranged around the waist of the wearer and in the vicinity thereof when worn. The waist elastic members 32 extend over substantially the entire length of the ventral portion A and the back portion B in the horizontal direction Y of the exterior body 3, and are arranged in a state in which elastic stretchability is expressed. This forms a substantially continuous annular waist gather around the entire circumference of the waist opening.

[0023] The exterior body 3 includes a plurality of thread-like or strip-like leg elastic members 37 arranged in a stretched state between the inner layer sheet 33 and the fixing sheet 35. Specifically, one or a plurality of leg elastic members 37 for forming leg gathers are arranged in a stretched state at leg edges LE forming the peripheries of each of a pair of leg openings in the front body F (see Figs. 1 and 2). As a result, leg gathers are formed at the peripheries of each of the pair of leg openings in the front body F. In the diaper 1 of this embodiment, the leg elastic members 37 are arranged only in the front body F. That is, the leg elastic members 37 are not arranged in the back body R. Alternatively, leg elastic members 37 may be provided at the leg edges LE of the front body piece F and the back body piece R, respectively.

[0024] The outer casing 3 of this embodiment has a front elastic region FE in the front body F that is elastic in the lateral direction Y, and a rear elastic region RE in the rear body R that is elastic in the same direction Y. The front elastic region FE and the rear elastic region RE are collectively referred to as "elastic regions". In this embodiment, these "elastic regions" are made of an elastic sheet that is one of the multiple sheets that make up the outer casing 3. In this embodiment, the elastic region is made of a front outer layer sheet 31a and a rear outer layer sheet 31b. The outer casing 3 is provided with an elastic sheet that is elastic, so that the diaper 1 fits the body when worn, and has an appearance like underwear.

[0025] The breaking elongation of the elastic sheet is preferably 30% or more and 200% or less, more preferably 50% or more and 180% or less, from the viewpoint of further improving the wearing comfort of the diaper 1. The method for measuring the breaking elongation will be described later.

[0026] As the elastic sheet used in the present invention, for example, (1) an elastic nonwoven fabric having a stretchable fiber layer integrated on both sides or one side of an elastic fiber layer, (2) an elastic nonwoven fabric having a stretchable fiber layer integrated on both sides or one side of a net-like elastic sheet, (3) an elastic nonwoven fabric having a stretchable fiber layer integrated on both sides or one side of an elastic sheet made of an elastic film, and (4) an elastic nonwoven fabric having a large number of elastic filaments arranged so as to extend in one direction without crossing each other and integrated into a stretchable fiber layer. The "stretchable fiber layer" referred to here includes not only a fiber layer that is stretchable before being integrated with an elastic material, but also a fiber layer that is made stretchable by mechanical processing or the like after being integrated with an elastic material. Methods for integrating the elastic fiber layer and the extensible fiber layer include, for example, laminating them and entangling the fibers by water flow entangling or air through, or bonding them by heat embossing, adhesives, ultrasonic waves, etc. As the elastic fiber, a fiber made of a thermoplastic elastomer such as a styrene-based elastomer, a polyolefin-based elastomer, a polyester-based elastomer, or a polyurethane-based elastomer, or an elastic resin such as rubber can be used. As the non-elastic fiber, a fiber made of a thermoplastic resin can be used.

[0027] The elastic nonwoven fabric of (4) above may be, for example, one having a structure in which a thread-like elastic filament is sandwiched between extensible fiber layers mainly made of inelastic fibers, and the layers are integrated together. Such an elastic nonwoven fabric is composed of two fiber sheets as fiber layers, and an elastic filament is interposed between the two sheets. This elastic nonwoven fabric can be produced, for example, according to the method described in JP 2009-61743 A.

[0028] In the elastic nonwoven fabric of (4), both of the two fiber sheets are stretchable. The two fiber sheets are stretchable in the same direction as the elastic filament. The stretchable form includes (a) a form in which the constituent fibers of the sheet themselves stretch, and (b) a form in which the constituent fibers themselves do not stretch, but the sheet as a whole stretches by mechanical processing or the like causing fibers bonded at intersections to separate, or by structurally changing the three-dimensional structure formed by multiple fibers due to bonding between fibers, or by tearing off the constituent fibers. Examples of mechanical processing in (b) include heat treatment, inter-roll stretching, biting stretching by teeth or gears, and tensile stretching by a tenter.

[0029] In the stretchable nonwoven fabric of (4) above, the elastic filament can be formed by stretching the elastic resin in a molten or softened state. The multiple elastic filaments are each arranged continuously in one direction and extend in that one direction without crossing each other. The elastic filament is bonded to the two fiber sheets in a substantially unstretched state. This bonding is achieved by fusing the constituent fibers (non-elastic fibers) of the two fiber sheets to the elastic filament in a state where the fibers are embedded in the elastic filament, and is not achieved using an adhesive such as a hot melt adhesive. Therefore, no adhesive is present between the two fiber sheets (stretchable fiber layers mainly composed of non-elastic fibers) and the elastic filament bonded thereto.

[0030] The two fiber sheets constituting the elastic nonwoven fabric of (4) can be various nonwoven fabrics such as air-through nonwoven fabric, heat roll nonwoven fabric, spunlace nonwoven fabric, spunbond nonwoven fabric, and meltblown nonwoven fabric. The two fiber sheets may be the same or different. Here, "same type of sheet" means sheets in which the manufacturing process of the sheet, the type of constituent fiber of the sheet, the fiber diameter and length of the constituent fiber, the thickness and basis weight of the sheet, etc. are all the same. When at least one of these is different, it is called "different type of sheet". In addition, the elastic filament is made of, for example, a thermoplastic elastomer or rubber. In particular, when a thermoplastic elastomer is used as a raw material, it is possible to melt-spin using an extruder like a normal thermoplastic resin, and the elastic filament obtained in this way is easy to heat-seal, so it is suitable for an elastic nonwoven fabric. From the viewpoint of further improving the fit to the wearer's body, it is preferable that the stretchable region is formed from the stretchable nonwoven fabric of (4) above. In this case, the extension direction of the elastic filaments of the stretchable nonwoven fabric forming the stretchable region coincides with the lateral direction Y.

[0031] The front outer layer sheet 31a of this embodiment extends inward in the longitudinal direction X beyond the inner end of the abdominal portion A, reaching the end of the abdominal portion A side of the crotch portion C. The rear outer layer sheet 31b of this embodiment also extends inward in the longitudinal direction X beyond the inner end of the dorsal portion B, reaching the end of the dorsal portion B side of the crotch portion C. As a result, in the longitudinal direction X, the front elasticated region FE extends to the end of the crotch portion C on the abdominal portion A side, and the rear elasticated region RE extends to the end of the crotch portion C on the dorsal portion B side (see FIG. 2).

[0032] The exterior body 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 exterior body 3 that does not stretch in the lateral direction Y, and is a region in which no stretchable member such as the stretchable sheet described above is arranged. In this embodiment, only a non-stretchable sheet is arranged in the non-stretchable region NE. Specifically, the non-stretchable region NE is a region in which no outer layer sheet 31 is arranged, and only the inner layer sheet 33, which is a non-stretchable sheet, is arranged (see FIG. 2). In this embodiment, the non-elasticated region NE is located in the center of the front body F and the back body R in the longitudinal direction X, and is sandwiched in the longitudinal direction X between the front elasticated region FE and the back elasticated region RE.

[0033] A non-elastic sheet is a sheet that has substantially no elasticity in a certain direction, and in this embodiment, it is a sheet that has no elasticity at least in the horizontal direction Y, and preferably has no elasticity in either the vertical direction X or the horizontal direction Y. A sheet that has no elasticity means that the sheet hardly stretches even when a pulling force is applied to the sheet in the certain direction. For example, if a sample of a sheet having a length of 15 cm and a width of 5 cm is pulled in the longitudinal direction of the sample using a material tensile tester such as Tensilon, and the breaking elongation at the time the sample breaks is 10% or less, the sample has substantially no elasticity in the longitudinal direction. This breaking elongation can be calculated by (the sample length at break - the original length of the sample) / (the original length of the sample) x 100.

[0034] The absorbent body 4 of this embodiment is disposed so as to bridge between the front stretchable region FE and the rear stretchable region RE via the non-stretchable region NE (see FIG. 2). The absorbent core 40 has a lower core 45 and an upper core 41 disposed on the skin-facing side of the lower core 45 (see Figs. 3 and 4). That is, the absorbent core 40 has a layered structure in which the upper core 41 and the lower core 45 are layered.

[0035] The lower core 45 of this embodiment has a long shape in the vertical direction X, similar to the absorbent body 4, and has an hourglass shape with both side edges at the center in the vertical direction X narrowed inward in the horizontal direction Y. The lower core 45 has a lower-layer low-rigidity portion 46 extending in the vertical direction X (see Figs. 1 and 2). The lower-layer low-rigidity portion 46 is a portion of the lower core 45 that has lower rigidity than other portions. For example, the lower-layer low-rigidity portion 46 is a low-weight portion in which the basis weight of the core-forming material that forms the lower core 45 is lower than other portions, or a portion in which the core-forming material is missing. Examples of the latter include a slit (through hole) that penetrates the lower core 45, or a bottomed recess. The other portion, i.e., the portion with a basis weight higher than the lower-layer low-rigidity portion 46, is also referred to as a lower-layer high-rigidity portion 47. The lower-layer low-rigidity portion 46 of this embodiment is a slit extending in the longitudinal direction X, and the basis weight of the material forming the absorbent core 40 (lower-layer core 45) is 0 g / m 2 Such a configuration is preferable in that it improves the fit of the diaper 1 and the underwear-like appearance (silhouette) of the diaper 1, which will be described later. The lower low stiffness portions 46 of the present embodiment are disposed spaced apart from both side edges and both ends in the longitudinal direction X of the lower core 45 , and are surrounded by the core-forming material of the lower core 45 .

[0036] The upper layer core 41 of this embodiment has a shape long in the vertical direction X, similar to the lower layer core 45, and is disposed in the center of the lower layer core 45 in the vertical direction X. The upper layer core 41 is disposed entirely within the non-stretchable region NE. In detail, the upper layer core 41 has an end 41a on the ventral portion A side in the vertical direction X located within the non-stretchable region NE, and an end 41b on the dorsal portion B side in the vertical direction X (hereinafter also referred to as "upper layer dorsal end 41b") also existing within the non-stretchable region NE.

[0037] In the present embodiment, both end portions in the longitudinal direction X of the lower core 45 are disposed in the stretchable region, and the narrowed central portion in the longitudinal direction X is disposed in the non-stretchable region NE (see FIG. 2). The lower low-rigidity portion 46 of this embodiment extends from the upper core 41 to both the ventral portion A and the dorsal portion B in the longitudinal direction X. That is, the lower low-rigidity portion 46 is longer in the longitudinal direction X than the upper core 41. In plan view, at least the end of the lower low-rigidity portion 46 on the back portion B side is present in the non-stretchable region NE. In this embodiment, the entire length of the lower low-rigidity portion 46 is contained within the non-stretchable region NE. That is, both ends of the lower low-rigidity portion 46 in the longitudinal direction X are located in the non-stretchable region NE. Alternatively, the end of the lower low-rigidity portion 46 on the back portion B side may be located in the non-stretchable region NE, and the end of the lower low-rigidity portion 46 on the ventral portion A side may extend into the front stretchable region FE. The lower low stiffness portion 46 of this embodiment is present at least in the non-elastic region NE, and extends further toward the back portion B than the upper layer back end portion 41b of the upper core 41 (see Figs. 1 and 2).

[0038] The absorbent core 40 of this embodiment has an upper layer core 41 arranged on the skin-facing surface of the lower layer core 45, so that the upper layer core 41 forms a convex portion that protrudes from the skin, and when worn, the upper layer core 41 fits the wearer's crotch area while ensuring absorption performance. In the absorbent core 40, the end of the lower low-rigidity portion 46 on the back side B side is present in the non-stretchable region NE in a plan view and extends further toward the back side B side than the upper core 41, so that the stretchable regions FE, RE allow the outer cover 3 to fit the wearer's skin while reducing the stiffness of the absorbent core 40 on the back side B side. Furthermore, since the entire upper core 41 is disposed within the non-stretchable region NE, the absorbent core 40 is prevented from being pressed excessively against the wearer's skin. With these configurations, the absorbent core 40 can be made to conform well to the shape of the buttocks, so that an excellent wearing comfort can be obtained and the appearance of the diaper 1 when worn can be made to have a neat silhouette like underwear (see FIG. 6). Furthermore, since the lower core 45 conforms to the shape of the buttocks, even if the wearer moves or the stretchable region stretches, it is possible to effectively prevent the diaper 1 from shifting its position when worn and the absorbent core 40 from excessively digging into the body. In particular, the leg edge LE of the rear body R can be prevented from digging excessively into the buttocks (see FIG. 6).

[0039] In order to improve the conformability of the absorbent core 40 to the body and thereby to further enhance the above-mentioned effects, it is preferable that the diaper 1 has the following configuration. The length L5 (see FIG. 2) of the lower-layer low-rigidity portion 46 in the longitudinal direction X is preferably 80% or more, more preferably 90% or more, and preferably 130% or less, more preferably 120% or less, relative to the length L8 (see FIG. 2) of the non-elastic region NE in the longitudinal direction X. Also, preferably 80% or more and 130% or less, more preferably 90% or more and 120% or less. The length L5 (see FIG. 2) of the lower low-rigidity portion 46 in the longitudinal direction X is preferably 100% or more, more preferably 110% or more, and preferably 200% or less, more preferably 180% or less, and preferably 100% or more and 200% or less, more preferably 110% or more and 180% or less, of the length L4 (see FIG. 2) of the upper core 41 in the longitudinal direction X. The length L4 (see FIG. 2) of the upper core 41 in the longitudinal direction X is preferably 60% or more, more preferably 70% or more, and is preferably 90% or less, more preferably 85% or less, and is preferably 60% or more and 90% or less, more preferably 70% or more and 85% or less, of the length L8 (see FIG. 2) of the non-elastic region NE in the longitudinal direction X.

[0040] The length L5 (see FIG. 2) of the lower low-rigidity portion 46 in the longitudinal direction X is preferably 200 mm or more, more preferably 250 mm or more, and is preferably 350 mm or less, more preferably 300 mm or less, and is preferably 200 mm or more and 350 mm or less, and more preferably 250 mm or more and 300 mm or less. The length L4 (see FIG. 2) of the upper core 41 in the longitudinal direction X is preferably 150 mm or more, more preferably 200 mm or more, and is preferably 300 mm or less, more preferably 250 mm or less, and is preferably 150 mm or more and 300 mm or less, more preferably 200 mm or more and 250 mm or less. The width W1 (see FIG. 2) of the lower layer low rigidity portion 46 is preferably 5 mm or more, more preferably 8 mm or more, and is preferably 20 mm or less, more preferably 15 mm or less, and is preferably 5 mm or more and 20 mm or less, more preferably 8 mm or more and 15 mm or less.

[0041] The lower layer low-rigidity portion 46 has an extension length L7 (see FIG. 2) from the upper layer back end portion 41b in the longitudinal direction X of preferably 20 mm or more, more preferably 30 mm or more, and preferably 100 mm or less, more preferably 80 mm or less, and preferably 20 mm or more and 100 mm or less, more preferably 30 mm or more and 80 mm or less.

[0042] The lower-layer low-rigidity portion 46 is preferably disposed in the center of the diaper 1 in the lateral direction Y (see Figs. 1 and 2). In this case, when the entire length of the diaper 1 in the lateral direction Y is divided into three equal parts, the lower-layer low-rigidity portion 46 is preferably located in the central region. With this configuration, the diaper 1 can be made to conform to the intergluteal cleft P of the wearer, further improving the underwear-like appearance (silhouette) (see Fig. 6). From the same viewpoint as above, it is preferable that the upper core 41 be disposed at the center of the lower core 45 in the lateral direction Y (see FIGS. 1 and 2). The width W3 (see FIG. 1) of the upper core 41 is preferably 40% or more, more preferably 50% or more, and preferably 80% or less, more preferably 70% or less, and preferably 40% or more and 80% or less, more preferably 50% or more and 70% or less, of the width W5 (see FIG. 1) of the lower core 45 in the non-elasticated region NE. When the width W3 of the upper core 41 varies in the longitudinal direction X, the width W3 is the maximum width. When the width W5 of the lower core 45 varies in the longitudinal direction X, the width is set to the minimum width.

[0043] In order to reduce the rigidity of the two-layer portion consisting of the upper core 41 and the lower core 45 and thereby improve the wearing comfort of the diaper 1, it is preferable that the lower low-rigidity portion 46 extends toward the ventral portion A further than the end portion 41a on the ventral portion A side of the upper core 41 (hereinafter also referred to as the "upper layer ventral end portion 41a") (see Figures 1 and 2). The lower layer low rigidity portion 46 has an extension length L1 (see FIG. 2) from the upper layer ventral end portion 41a in the longitudinal direction X of preferably 5 mm or more, more preferably 8 mm or more, and preferably 100 mm or less, more preferably 70 mm or less, and preferably 5 mm or more and 100 mm or less, more preferably 8 mm or more and 70 mm or less.

[0044] From the viewpoint of further reducing the rigidity of the absorbent core 40 and further improving the wearing comfort of the diaper 1, it is preferable that the upper core 41 has an upper-layer low-rigidity portion 42 extending in the longitudinal direction X (see Figs. 4 and 5). The upper-layer low-rigidity portion 42 is a low-basis weight portion in which the basis weight of the core-forming material constituting the upper core 41 is lower than that of other portions, or a portion in which the core-forming material is missing, and the same explanation as for the lower-layer low-rigidity portion 46 described above applies. The other portions, i.e., the portions having a basis weight higher than that of the upper-layer low-rigidity portion 42, are also referred to as upper-layer high-rigidity portions 43. In order to further improve the ability of the upper layer core 41 to conform to the body, the upper layer low-rigidity portion 42 is preferably a slit (through hole) extending in the longitudinal direction X. The upper low rigidity portions 42 of this embodiment are disposed spaced apart from both side edges and both ends in the longitudinal direction X of the upper core 41 , and are surrounded by the core-forming material that forms the upper core 41 .

[0045] In order to further improve the above-mentioned effects, upper core 41 preferably has the following configuration. The length L3 (see FIG. 2) of the upper layer low rigidity portion 42 in the longitudinal direction X is preferably 25% or more, more preferably 30% or more, and preferably 90% or less, more preferably 80% or less, and preferably 25% or more and 90% or less, more preferably 30% or more and 80% or less, of the length L4 (see FIG. 2) of the upper layer core 41 in the longitudinal direction X. The width W7 (see FIG. 1) of the upper layer low rigidity portion 42 is preferably 10% or more, more preferably 15% or more, and preferably 40% or less, more preferably 30% or less, and preferably 10% or more and 40% or less, more preferably 15% or more and 30% or less, of the width W3 (see FIG. 1) of the upper layer core 41. The length L3 (see FIG. 2) of the upper low rigidity portion 42 in the longitudinal direction X is preferably 60 mm or more, more preferably 70 mm or more, and is preferably 210 mm or less, more preferably 180 mm or less, and is preferably 60 mm or more and 210 mm or less, more preferably 70 mm or more and 180 mm or less. The width W7 (see FIG. 1) of the upper layer low rigidity portion 42 is preferably 5 mm or more, more preferably 8 mm or more, and is preferably 20 mm or less, more preferably 15 mm or less, and is preferably 5 mm or more and 20 mm or less, more preferably 8 mm or more and 15 mm or less.

[0046] From the viewpoint of further improving the fit to the body and further improving the appearance (silhouette) of the diaper 1, it is preferable that the lower-layer low-rigidity portion 46 and the upper-layer low-rigidity portion 42 at least partially overlap each other in a plan view (see Figs. 1 and 2). With such a configuration, the low-rigidity portions overlap each other, so that the diaper 1 can better conform to the wearer's body and improve the wearing comfort. In the absorbent core 40 of this embodiment, the upper low stiffness portion 42 entirely overlaps the lower low stiffness portion 46 . From the viewpoint of further enhancing the above-mentioned effect, the length in the vertical direction X of the portion where the lower-layer low-rigidity portion 46 and the upper-layer low-rigidity portion 42 overlap is preferably 80% or more, more preferably 90% or more, and preferably 100% or less, more preferably 98% or less, relative to the length L3 in the vertical direction X of the upper-layer low-rigidity portion 42, and is preferably 80% or more and 100% or less, more preferably 90% or more and 98% or less.

[0047] The diaper 1 of this embodiment has elastic members (hereinafter also referred to as "side elastic members") arranged in a stretched state in the longitudinal direction X on both sides in the lateral direction Y of the absorbent core 40. The side elastic members are elastic members located on both sides in the lateral direction Y of the absorbent core 40, preferably on the outer sides in the lateral direction Y of the absorbent core 40. Examples of the side elastic members include the above-mentioned intermediate elastic members 48. Since the upper layer core 41 is flexibly deformed by having the upper layer low rigidity portion 42, it is preferable that the end of the side elastic member on the back portion B side is located outward in the vertical direction X from the upper layer core 41. In other words, it is preferable that the end of the side elastic member on the back portion B side is located outward in the vertical direction X from the upper layer back end portion 41b. The side elastic members in this embodiment are intermediate elastic members 48, which extend outward in the vertical direction X beyond the upper layer back end portion 41b (see Figs. 1 and 2). In this configuration, contraction of the intermediate elastic members 48 causes the cross section of the entire upper layer core 41 along the vertical direction X to curve, and tends to assume a shape that conforms to the wearer's buttocks. This makes it easier for the upper layer core 41 to fit the wearer's buttocks.

[0048] In order to ensure the above-mentioned effects, the extension length L9 (see FIG. 1) of the side elastic member from the upper layer back end 41b is preferably 5 mm to 180 mm, more preferably 10 mm to 170 mm. The extension length L9 (see FIG. 1) is the length between the upper layer back end 41b in the longitudinal direction X and the edge of the stretchable portion of the side elastic member on the back part B side.

[0049] In order to achieve a good balance between fit and absorbency, the upper core 41 preferably has a basis weight of 100 g / m 2 More preferably, 130 g / m 2 More preferably, it is 200 g / m 2 Less than 180 g / m 2 and preferably 100 g / m 2 More than 200g / m 2 Less than 130 g / m 2 More than 180g / m 2 The following is the result. From the same viewpoint as above, the basis weight of the lower core 45 is preferably 80 g / m 2 More preferably, 90 g / m 2 More preferably, it is 130 g / m 2 Less than 120 g / m 2 and preferably 80 g / m 2 More than 130g / m 2 Less than 90g / m 2 More than 120g / m 2 The following is the result. The basis weights of the upper core 41 and the lower core 45 are the basis weights of the portions other than the low stiffness portions 42 and 46 .

[0050] When either or both of the upper low-rigidity portion 42 and the lower low-rigidity portion 46 are low-basis weight portions in which the core-forming material that forms the upper core 41 or the lower core 45 is present, in order to ensure the fit of the absorbent core 40, it is preferable that the basis weight of the upper core 41 or the lower core 45 be in the following range. The upper core 41 has a difference in basis weight between the upper low-rigidity portion 42 and the other portion (upper high-rigidity portion 43) of preferably 50 g / m 2 More preferably, 70 g / m 2 More preferably, it is 200 g / m 2 Less than 180 g / m 2 and preferably 50 g / m 2 More than 200g / m 2 Less than 70 g / m 2 More than 180g / m 2 The following is the result. The lower core 45 has a difference in basis weight between the lower low stiffness portion 46 and the other portion (lower high stiffness portion 47) of preferably 30 g / m 2 More preferably, 50 g / m 2 More preferably, it is 180 g / m 2 Less than 150 g / m 2 and preferably 30 g / m 2 More than 180g / m 2 Less than 50 g / m 2 More than 150g / m 2 The following is the result.

[0051] In order to make the outer body 3 fit the body and achieve a more underwear-like appearance, the elongation rate of the elastic region is preferably 105% or more, more preferably 110% or more, and also preferably 130% or less, more preferably 125% or less, and also preferably 105% or more and 130% or less, more preferably 110% or more and 125% or less. The elongation rate of the elastic region is measured by the following method.

[0052] [Method of measuring elongation rate] Since the stretchable region is composed of a sheet member such as a stretchable sheet, the sheet member that exhibits stretch performance in the exterior body is the subject of measurement. First, with the diaper in its natural state, two marks are made on the sheet member that constitutes the stretchable region of the exterior body, spaced 50 mm apart in the stretch direction (horizontal direction Y). With the sheet member in its maximally stretched state, the distance between the two marks is measured as the stretch distance (mm). Then, the stretch rate of the stretchable region is calculated using the following formula (1). Stretch rate of stretchable area (%) = [stretch distance (mm) / 50 (mm)] × 100 (1)

[0053] Next, a description will be given of the materials forming each part of the diaper 1. As the inner layer sheet 33 and the fixing sheet 35, various materials conventionally used as exterior bodies in this type of absorbent article can be used without any particular restrictions. For example, as the inner layer sheet 33, nonwoven fabrics produced by various manufacturing methods such as spunbond nonwoven fabric, air-through nonwoven fabric, needle punch nonwoven fabric, etc. can be used.

[0054] The elastic members 32, 37, 48, 61 such as the leg elastic members are preferably made of elastic materials such as natural rubber, polyurethane resin, urethane foam resin, and hot melt elastic materials formed into threads (rubber threads) or bands (rubber strips). The top sheet 12 may be made of various nonwoven fabrics or perforated films, and the leak-proof sheet 13 may be made of a resin film or a laminate of a resin film and a nonwoven fabric.

[0055] The absorbent core 40 of the absorbent body 4 is formed from core-forming materials such as hydrophilic fibers such as cellulose including pulp, and water-absorbent polymers. The absorbent core 40 is composed of, for example, a pile of hydrophilic fibers, a mixed pile of the hydrophilic fibers and water-absorbent polymers, a pile of water-absorbent polymers, a laminated structure in which water-absorbent polymers are supported between two absorbent sheets, or the like. The core wrap sheet 49 may be, for example, tissue paper made of hydrophilic fibers or liquid-permeable nonwoven fabric.

[0056] While the present invention has been described above based on its preferred embodiments, the present invention is not limited to the above-described embodiments and can be modified as appropriate without departing from the spirit of the present invention. For example, the diaper 1 in the above-described embodiment has the leg elastic members 37 only on the front body piece F, but it may have the leg elastic members 37 on both the front body piece F and the rear body piece R. In the diaper 1 of the above-described embodiment, the lower core 45 has an hourglass shape, but the side edges of the lower core 45 do not have to be narrowed inward in the horizontal direction Y, and the side edges may be parallel to the vertical direction X. Further, although the upper core 41 in the above-described embodiment has the upper low stiffness portion 42, the upper core 41 does not have to have the upper low stiffness portion 42. [Explanation of symbols]

[0057] 1. Pants-type disposable diapers (diapers) 3 Exterior body 4. Absorber 5. Absorbent body 6 Leak proof cuff 12 Surface sheet 13 Leak-proof sheet 31 Outer layer sheet 32 Waist elastic member 33 Inner sheet 34 End fixing sheet 35 Fixing sheet 37 Leg elastic member 40 Absorbent Core 41 Upper Core 42 Upper layer low rigidity part 43 Upper layer high rigidity part 45 Lower Core 46 Lower layer low rigidity part 47 Lower layer high rigidity section 48 Intermediate elastic member 49 Core wrap sheet 60 Cuff forming sheet 61 Cuff elastic member A Ventral part B Dorsal part C Inseam F Front R Back FE front stretch area RE Posterior stretch area NE non-stretchable region X vertical direction Y Horizontal

Claims

1. An absorbent body having a ventral part disposed on the ventral side of the wearer, a dorsal part disposed on the dorsal side of the wearer, and a crotch part located between the ventral part and the dorsal part, and having a longitudinal direction extending from the ventral part through the crotch part to the dorsal part and a transverse direction orthogonal to the longitudinal direction, the absorbent body including an absorbent core, and an outer wrapper disposed on the non-skin-facing surface side of the absorbent body, having a waist opening and a pair of leg openings, and being a pant-type disposable diaper that is divided into a front body part disposed on the ventral side of the wearer and a back body part disposed on the dorsal side of the wearer with the center in the longitudinal direction as a boundary when worn, The outer wrapper has a front stretch region having elasticity along the transverse direction in the front body part, a rear stretch region having elasticity along the transverse direction in the back body part, and a non-stretch region located between the front stretch region and the rear stretch region, The absorbent core has a lower layer core and an upper layer core disposed on the skin-facing surface side of the lower layer core, and the lower layer core has a lower layer low-rigidity part extending in the longitudinal direction, The entire upper layer core is disposed within the non-stretch region, The lower layer low-rigidity part is, in a plan view, at least the end on the dorsal part side existing in the non-stretch region and extending to the dorsal part side beyond the end on the dorsal part side of the upper layer core, the disposable diaper.

2. The lower layer low-rigidity part is disposed at the center in the transverse direction of the disposable diaper according to claim 1.

3. The lower layer low-rigidity part consists of a slit, the disposable diaper according to claim 1 or 2.

4. The lower layer low-rigidity part extends to the ventral part side beyond the end on the ventral part side of the upper layer core, the disposable diaper according to claim 1 or 2.

5. The upper layer core has an upper layer low-rigidity part extending in the longitudinal direction, the disposable diaper according to claim 1 or 2.

6. The disposable diaper according to claim 5, wherein the upper low-rigidity portion is formed of a slit.

7. The disposable diaper according to claim 5, wherein the lower low-rigidity portion and the upper low-rigidity portion overlap at least partially in plan view.

8. The disposable diaper according to claim 1 or 2, wherein the front stretchable region and the rear stretchable region are formed of a stretchable sheet having stretchability in the lateral direction.

9. The disposable diaper according to claim 1 or 2, having elastic members arranged in an extended state in the longitudinal direction on both lateral sides of the absorbent core, and the end portions of the elastic members on the back side portion side are located outward in the longitudinal direction than the upper core.

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