GB2591901A

GB2591901A - Disposable diaper

Info

Publication number: GB2591901A
Application number: GB2103877.3A
Authority: GB
Inventors: Matsuda Kohei
Original assignee: Kao Corp
Current assignee: Kao Corp
Priority date: 2018-10-01
Filing date: 2018-10-01
Publication date: 2021-08-11
Anticipated expiration: 2038-10-01
Also published as: CN112789018A; JP7168677B2; WO2020070780A1; GB2591901B; GB202103877D0; DE112018008043T5; JPWO2020070780A1; CN112789018B; RU2759896C1

Abstract

A disposable diaper according to the present invention comprises: an absorbent; a non-skin surface sheet disposed on the non-skin-facing surface side of the absorbent; and an outer surface sheet disposed on the non-skin-facing surface side of the non-skin surface sheet. The disposable diaper has, in a state of being worn, a ventral-side section located on the ventral side of the wearer, a crotch section located on the crotch of the wearer, and a dorsal-side section located on the dorsal side of the wearer. The absorbent has a low-basis-weight part located at any position from the crotch section to the dorsal-side section and having a relatively low basis weight than the other part of the absorbent. In the disposable diaper, the outer surface sheet and a sheet located on the skin-facing surface side of the outer surface sheet are adhered to each other with an adhesive so that multiple lines of adhesion sections are formed so as to extend in the diaper longitudinal direction. The multiple lines of adhesion sections are located in a region that overlaps with the low-basis-weight part. In each of side regions located at both side portions in the diaper width direction of the aforementioned region, the weight of the adhesive is higher than that in a center region located at a center portion in the diaper width direction of the aforementioned region.

Description

DESCRIPTION

Title of Invention: DISPOSABLE DIAPER

Technical Field [0001]

The present invention relates to a disposable diaper.

Background Art

[0002] There have been proposed diapers capable of preventing excreta with a relatively high water content, such as watery stool or muddy stool, from leaking outside. For example, Patent Literature 1 discloses a diaper wherein a pocket-forming portion having a downwardly-openable pocket is formed in a rear waist area. The Literature describes that the pocket-forming portion includes: a pocket inner-side area extending upward from both lateral-side fixing parts which are fixed to a belt-shaped area; a pocket outer-side area located on an extension of an absorbent member; and pocket lateral-side areas formed respectively from both lateral sides of the pocket outer-and inner-side areas. The pocket inner-side area of the pocket-forming portion is contracted and shortened in the lateral direction, so that both the pocket lateral-side areas are folded inward in the lateral direction.

Citation List Patent Literature [0003] Patent Literature 1 JP 2016-67958A

Summary of Invention [0004]

The present invention relates to a disposable diaper including: an absorbent member; a non-skin-surface sheet arranged on a non-skin-facing surface side of the absorbent member; and an outer-surface sheet arranged on a non-skin-facing surface side of the non-skin-surface sheet, the disposable diaper including a front portion to be arranged on a front side of a wearer in a state where the disposable diaper is worn, a crotch portion to be arranged in the wearer's crotch section, and a rear portion to be arranged on the wearer's rear side. The absorbent member includes a low-basis-weight portion in any position within a range from the crotch portion to the rear portion, the low-basis-weight portion having a basis weight relatively lower than other sections of the absorbent member.

The outer-surface sheet and a sheet located on a skin-facing surface side of the outer-surface sheet are joined by an adhesive, and thereby, a plurality of joined portions extending in a longitudinal direction of the diaper are formed. The plurality of joined portions are located in a region overlapping the low-basis-weight portion in a thickness direction. In the aforementioned region, a basis weight of the adhesive in side regions located respectively in both side areas in a width direction of the diaper is higher than the basis weight of the adhesive in a central region located in a central area in the width direction.

Brief Description of Drawings [0005]

[Fig. 1] Fig. 1 is a perspective view schematically illustrating a disposable diaper of the present invention in a natural state.

[Fig. 2] Fig. 2 is a developed plan view schematically illustrating a skin-facing surface side (inner surface side) of the diaper illustrated in Fig. 1 in a spread-open and stretched state.

[Fig. 3] Fig. 3(a) is a cross-sectional view illustrating an embodiment of the diaper illustrated in Fig. 2 taken along line A-A, and Fig. 3(b) is a cross-sectional view illustrating an embodiment of the diaper illustrated in Fig. 2 taken along line B-B.

[Fig. 4] Fig. 4(a) is a plan view illustrating an embodiment of an absorbent member of the diaper illustrated in Fig. 2, and Fig. 4(b) is a side view along line I-I of the absorbent member of Fig. 4(a).

[Fig. 5] Fig. 5 is a schematic diagram illustrating an embodiment ofjoined portions on an outer-surface sheet [Fig. 6] Fig. 6 is a perspective view schematically illustrating a state after using a disposable diaper according to the present invention.

[Fig. 7] Fig. 7 is a schematic diagram illustrating another embodiment of joined portions on an outer-surface sheet.

[Fig. 8] Fig. 8 is a cross-sectional view illustrating another embodiment of the diaper illustrated in Fig. 2 taken along line A-A.

[Fig. 91 Fig. 9 is a plan view illustrating another embodiment of an absorbent member of the diaper illustrated in Fig. 2.

Description of Embodiments

[0006] In the diaper disclosed in Patent Literature 1, the pocket is formed in the diaper's rear portion. This causes the absorbent assembly to project toward the diaper's skin-facing surface side, thus impairing wearing comfort. Further, in the diaper disclosed in Patent Literature 1, the presence of the pocket causes the diaper's rear portion to bulge out, thus impairing the diaper's appearance.

[0007] The present invention relates to a disposable diaper and a manufacturing method therefor capable of overcoming the drawbacks of conventional art.

[0008] A disposable diaper of the present invention will be described below according to preferred embodiments thereof Figs. 1 to 3 illustrate a pull-on disposable diaper which is an embodiment of a disposable diaper of the present invention. The diaper 1 includes, in a state where it is worn, a front portion F to be arranged on the front side of a wearer, a rear portion R to be arranged on the wearer's rear side, and a crotch portion NI located between the front and rear portions and to be arranged in the wearer's crotch section.

These members extend continuously in the wearer's front-rear direction. The diaper 1 has a diaper longitudinal direction X extending from the wearer's front side to the rear side via the crotch section (referred to hereinafter also as "longitudinal direction X"), and a diaper width direction Y orthogonal thereto (referred to hereinafter also as "width direction Y").

[0009] As illustrated in Figs. 1 and 2, the diaper 1 includes: an absorbent assembly 2 including an absorbent member 23 capable of absorbing and retaining excreta; and an outer cover 3 arranged on the non-skin-facing surface side of the absorbent assembly 2. In the diaper I, both lateral side edge portions on the front side are joined respectively to both lateral side edge portions on the rear side by a known joining means such as an adhesive, heat sealing, or ultrasonic sealing, thereby forming a pair of side seals S and S, as well as a waist opening WH through which the wearer's body passes, and a pair of leg openings LH through which the wearer's legs pass. Details on the outer cover 3 will be described further below.

[0010] Although not illustrated in the figures, the diaper of the present invention may be a so-called open-type disposable diaper, instead of the aforementioned embodiment.

More specifically instead of the pair of side seals S and S, a pair of fastening tapes may be provided respectively to both lateral side edge portions extending along the longitudinal direction X in the diaper 1 's rear portion R. Each fastening tape may include an attachment portion. A target region to which the attachment portions of the respective fastening tapes can be detachably fastened may be formed on the non-skin-facing surface of the diaper l's front portion F. The target region may be formed by being joined/fixed to a non-skin-facing surface of a non-skin-surface sheet, which forms the non-skin-facing surface of the front portion F. [0011] In the present Description, "skin-facing surface" refers to the surface of the diaper, or a constituent member thereof (e.g., the absorbent assembly), which will face the wearer's skin side when the diaper is worn. "Non-skin-facing surface" refers to the surface which will face the opposite side from the skin side when the diaper is worn. Stated differently, the skin-facing surface is the surface relatively closer to the wearer's skin, whereas the nonskin-facing surface is the surface relatively farther from the wearer's skin. "When worn" refers to a state where the diaper is maintained in its properly worn position.

[0012] As illustrated in Fig. 1, the diaper 1 includes, between the waist opening WH and the leg openings LH, a below-waist portion W to be arranged around the wearer's waist/hip portion when the diaper is worn. The below-waist portion W is a region located in the same position, in the longitudinal direction X, as the side seals S of the diaper 1, and in the present embodiment, the front portion F constitutes the front-side below-waist portion W, and the rear portion R constitutes the rear-side below-waist portion W. [0013] As illustrated in Fig. 2, the absorbent assembly 2 has a substantially rectangular shape in a spread-open and stretched state of the diaper 1, and is provided extending from the front portion F to the rear portion R. The longitudinal direction of the absorbent assembly 2 matches the longitudinal direction X of the diaper 1. The absorbent assembly 2 is arranged in a central portion, in the width direction Y, of the outer cover 3. The absorbent assembly 2 is joined to the outer cover 3 by a joining means such as an adhesive.

The "spread-open and stretched state" of the diaper 1 refers to a state in which the diaper 1 is spread opened by cutting apart the side seals S or releasing the fastening between the fastening tapes' attachment portions and the target region, and the spread-open diaper 1 is stretched and expanded to its designed size (i.e., the size when the diaper is spread out in a planar manner in a state where the effect of extensible members is completely eliminated).

[0014] As illustrated in Figs. 2 and 3, the absorbent assembly 2 includes: a liquid-permeable skin-surface sheet 21 forming the skin-facing surface; a sparingly liquid-permeable (including water-repellent) non-skin-surface sheet 22 forming the non-skin-facing surface; and a liquid-retentive absorbent member 23 interposed between the two sheets 21 and 22. The absorbent member 23 is formed such that an absorbent core 231 having absorbency is covered by a liquid-permeable core-wrap sheet 232. The absorbent member 23 is in direct contact with the skin-surface sheet 21 and the non-skin-surface sheet 22.

[0015] The absorbent member 23 of the absorbent assembly 2 includes a low-basis-weight portion 2L in any position within a range in the longitudinal direction X from the crotch portion M to the rear portion R, the low-basis-weight portion 2L having a basis weight relatively lower than other sections of the absorbent member 23 In the longitudinal direction X, the low-basis-weight portion 2L may be located only in the crotch portion Ni, or may be located only in the rear portion R, or may be located in both the crotch portion Ni and the rear portion R. The low-basis-weight portion 2L may be present in the entire region, or only partially, in the width direction Y. The absorbent member 23 illustrated in Fig. 4(a) includes a single low-basis-weight portion 2L in the entire region, in the longitudinal direction X and the width direction Y, of only the rear portion R, and no lowbasis-weight portion 2L is present in the crotch portion NI. As illustrated in Fig. 4(b), in the low-basis-weight portion 2L, the skin-facing surface side of the absorbent member 23 is depressed toward the non-skin-facing surface side, and the thickness of the low-basis-weight portion 2L gradually decreases toward an end-side edge of the rear portion R. [0016] The absorbent member 23 includes a high-basis-weight portion 2H having a higher basis weight than the low-basis-weight portion 2L. In an embodiment having a shape different from that illustrated in Fig. 4(b), the boundary between the low-basis-weight portion 2L and the high-basis-weight portion 2H may be formed as a step. The hi gh-basi s-weight portion 211 may be provided separately in two or more sections in the absorbent member 23. In this case, the high-basis-weight portions 2H formed in two or more sections may have the same basis weight, or may have different basis weights. In cases where there are three or more regions having different basis weights in the absorbent member 23, the region with the lowest basis weight is defined as the low-basis-weight portion 2L, and the other regions are defined as high-basis-weight portions 211. The lowbasi s-weight portion 2L may be present in any position within a range from the crotch portion Ni to the rear portion R, and may be present in other positions as necessary [0017] Any material conventionally used in absorbent articles may be used without particular limitation for the skin-surface sheet 21, the non-skin-surface sheet 22, and the absorbent member 23. For example, for the skin-surface sheet 21, it is possible to use one of various types of nonwoven fabrics or porous films. For the non-skin-surface sheet 22, it is possible to use, for example, a resin film or a laminate of a resin film and a nonwoven fabric For the absorbent core 231 of the absorbent member 23, it is possible to use, for example, an aggregate of hydrophilic fibers, such as wood pulp or hydrophilized synthetic fibers, or a member in which a water-absorbent polymer is retained in the aforementioned aggregate. For the core-wrap sheet 232, it is possible to use a sheet similar to the skin-surface sheet 21.

[0018] As illustrated in Fig. 3, an outer-surface sheet 25 is arranged on the non-skin-facing surface side of the non-skin-surface sheet 22 of the absorbent assembly 2. The outer-surface sheet 25 is arranged at least in the crotch portion NI of the absorbent assembly 2, and preferably extends up to the front portion F and the rear portion R via the crotch portion M. Sections of the outer-surface sheet 25 located respectively in the front portion F and the rear portion R are arranged at least between the absorbent assembly 2 and the later-described outer cover 3. The outer-surface sheet 25 may be exposed to the outer surface of the diaper 1 only in the crotch portion M, or may not be exposed in any of the front portion F, the crotch portion NI, or the rear portion R by making the outer cover 3 cover also the crotch portion M. [0019] Returning to Fig. 2, the diaper 1 includes an outer cover 3. The outer cover 3 is arranged on the non-skin-facing surface side of the outer-surface sheet 25, and is a member forming the outer surface of the diaper I. As illustrated in Fig. 2, the peripheral edge of the outer cover 3 forms at least an outline of each of the front portion F and the rear portion R of the diaper I. The outer cover 3 located in each of the front portion F and the rear portion R has a rectangular shape that is longer in the width direction Y than in the longitudinal direction X, and forms the below-waist portion W. Stated differently, in the diaper t illustrated in Fig. 2, the outer cover 3 is divided into a rear outer cover 3R to be arranged on the wearer's rear side, and a front outer cover 3F to be arranged on the wearer's front side, and the absorbent assembly 2 is fixed so as to bridge the rear outer cover 3R and the front outer cover 3F. Instead, a diaper according to another embodiment of the present invention may be formed such that the outer cover 3 is continuously arranged spanning the crotch portion NI in addition to the front portion F and the rear portion R. [0020] As illustrated in Fig. 3(b), the outer cover 3 includes a laminate including an outer-layer nonwoven fabric 31 that forms the non-skin-facing surface of the diaper] when worn, and an inner-layer nonwoven fabric 32 arranged on the skin-facing surface side of the outer-layer nonwoven fabric 31. In a state where the diaper] is worn, the outer-layer nonwoven fabric 31 forms the non-skin-facing surface of the diaper 1, and the inner-layer nonwoven fabric 32 forms the skin-facing surface of the diaper 1. The outer-layer nonwoven fabric 31 and the inner-layer nonwoven fabric 32 are joined together by a joining means, such as an adhesive, at predetermined sections. In relation to the outer-surface sheet 25, the inner- layer nonwoven fabric 32 is arranged on the non-skin-facing surface side of the outer-surface sheet 25, and the outer-layer nonwoven fabric 31 is arranged on the non-skin-facing surface side of the inner-layer nonwoven fabric 32.

[0021] Note that, although Fig. 3(b) is illustrated such that there is a space between the outer-layer nonwoven fabric 31 and the inner-layer nonwoven fabric 32, as well as between the inner-layer nonwoven fabric 32 and the outer-surface sheet 25, this illustration is merely for the sake of explanation, and actually, the nonwoven fabrics, as well as the sheets, are not separated but are joined or otherwise connected together, although not illustrated in the figure [0022] As illustrated in Figs. 1 and 2, a plurality of thread-shaped or band-shaped second elastic members 33 are provided between the outer-layer nonwoven fabric 31 and the inner-layer nonwoven fabric 32, with intervals therebetween in the diaper's longitudinal direction X. The second elastic members 33 extend along the diaper's width direction Y, and a plurality of the second elastic members 33 are fixed between the outer-layer nonwoven fabric 31 and the inner-layer nonwoven fabric 32 in a stretched state. Contraction of the second elastic members 33 forms below-waist gathers in the below-waist portion W when the diaper 1 is worn. The below-waist gathers are formed so as to extend along the width direction Y, which is the direction in which the second elastic members 33 can expand and contract [0023] As illustrated in Figs. 3 and 5, the outer-surface sheet 25 and a sheet located on the skin-facing surface side of the outer-surface sheet 25 are joined by an adhesive, and thereby, a plurality of joined portions 27 are formed in a manner extending in the diaper's longitudinal direction X but non-continuously in the width direction Y. In a planar view of the diaper 1, the joined portions 27 are located in a region overlapping the low-basisweight portion 2L of the absorbent assembly 2 in the thickness direction, and are formed extending in the longitudinal direction X. The joined portions 27 include joined portions 27a (referred to hereinafter also as -central joined portions 27a") formed in a central region located in a central area in the width direction Y of the diaper 1, and joined portions 27b (referred to hereinafter also as "side joined portions 27b") formed in side regions located respectively in both side areas in the width direction Y, and the joined portions overlap the low-basis-weight portion 2L in the thickness direction. The central joined portions 27a are formed by joining the outer-surface sheet 25 to the non-skin-surface sheet 22 in the central area in the width direction Y The side joined portions 27b are formed by joining the outer-surface sheet 25 to a later-described intermediate sheet 29 in each of the side areas in the width direction Y. A region in which the joined portions 27 overlap the absorbent assembly 2's low-basis-weight portion 2L in the thickness direction is constituted by the central region 27C and side regions 27S. The central region 27C includes the central joined portions 27a and is located in the central section in the diaper's width direction.

The side regions 27S are located respectively on both lateral sides in the diaper's width direction, with the central region 27C therebetween. The basis weight of the adhesive in the central region 27C is different from that in the side regions 27S, and preferably, the basis weight of the adhesive in the side regions 27S is higher than the basis weight of the adhesive in the central region 27C.

[0024] More specifically, various configurations are conceivable, such as: (1) making the basis weight of the adhesive in the central region 27C different from that in the side regions 275 by forming each of the joined portions 27a and 27b, which are present in the regions 27C and 27S, by applying the same amount of adhesive, while applying the adhesive so that the application intervals are different in each of the regions; or (2) making the basis weight of the adhesive in the central region 27C different from that in the side regions 27S by applying a greater amount of adhesive for the side joined portions 27b, which are present in the side regions 27S, than the central joined portions 27a, which are present in the central region 27C, while applying the adhesive so that the application interval is the same; or (3) making the basis weight of the adhesive in the central region 27C different from that in the side regions 27S by varying both the application amount and application interval of the adhesive.

[0025] The diaper 1 may further include an intermediate sheet 29 in each of both side-portion areas in the width direction Y. As illustrated in Fig. 3, the intermediate sheet 29 is located between the non-skin-surface sheet 22 and the outer-surface sheet 25. The intermediate sheet 29 is made from a nonwoven fabric that is air-permeable and liquid-resistant or water-repellent. The intermediate sheet 29 is formed at least in the crotch portion Ni of the absorbent assembly 2.

[0026] In the intermediate sheet 29, a fixed end portion 29c extending along the longitudinal direction X is located between the non-skin-surface sheet 22 and the outer-surface sheet 25, and a free end portion 29a side is folded toward the skin-facing surface side of the absorbent member 23 to form a leak-proof cuff. Elastic members 29b are provided in a stretched state to a free end 29S of the leak-proof cuff, which is located on the free end portion 29a side. Thereby, the intermediate sheet 29 has extensibility along the longitudinal direction X. Contraction of the elastic members 29b enables the intermediate sheets 29 to stand up toward the wearer's skin, with each of both lateral side edges of the absorbent member 23 in the width direction Y, or the vicinity thereof, serving as a base point. The elastic members 29b are arranged along the longitudinal direction X, and are fixed to the intermediate sheet 29 in a stretched state. In the intermediate sheet 29, the fixed end portion 29c, which is located at a lateral side edge on the opposite side from the free end portion 29a, is joined by being located between the absorbent assembly 2's non-skin-surface sheet 22 and the outer-surface sheet 25.

[0027] As illustrated in Figs. 3(a) and 3(b), the fixed end portion 29c includes a second joined portion 27A in which the non-skin-surface sheet 22 and the intermediate sheet 29 are joined with an adhesive. The second joined portion 27A is formed by joining the nonskin-surface sheet 22 and the intermediate sheet 29, and is formed so as to overlap the side joined portions 27b in the thickness direction Z. A region in which the second joined portion 2A is formed is formed so as to overlap the side region 27S in the thickness direction Z. [0028] With the diaper I according to the present embodiment having the aforementioned configuration, no pocket nor other such components will be formed on the diaper's outer surface immediately after putting on the diaper, and this will make the diaper's appearance neat and uncluttered, with few projections and depressions, thus improving the diaper's outer appearance. Further, after excretion of excreta, such as feces, having a relatively large weight, the absorbent member's central area in the width direction will deform so as to protrude outward and form a pocket 1P capable of envelopingly receiving feces.

Therefore, as illustrated in Fig. 6, even feces with a high water content can be retained successfully in the absorbent member's central area in the width direction. Thus, leakage of feces can be prevented. The absorbent member's central area in the width direction deforms for the following reasons. First, the absorbent member has a low-basis-weight portion, which is easily deformable. In addition, the basis weight of the adhesive is lower in the central region 27C, where the central joined portions 27a are present, than in the side regions 27S, where the side joined portions 27b are present, and this thereby makes the non-skin-surface sheet 22 and the outer-surface sheet 25 easily deformable in the central area in the width direction.

[0029] Preferably, the length of the joined portions 27 along the longitudinal direction X is formed longer than the length of the low-basis-weight portion 2L. With this configuration, it is possible to form a pocket I P capable of envelopingly retaining excreta in the entire region of the low-basis-weight portion 2L, thereby enabling more effective prevention of leakage of excreta [0030] Preferably, the central region 27C is formed within a range from 40 to 70%, with respect to the entire length of the absorbent member 23 in the width direction Y, spanning both sides of the center portion of the absorbent member 23. Further, preferably, each of the side regions is formed within a range from 15 to 30%, with respect to the entire length of the absorbent member 23 in the width direction Y, from one of both lateral side edges of the absorbent member 23. With this configuration, it is possible to increase the rigidity in the side regions 27S where the side joined portions 27b are present, thereby further facilitating the formation of the pocket 1P for receiving feces. The boundary between the central region 27C and the side region 27S is defined as an end on the center side, in the width direction, of the side joined portion 27b that is located closest to the center side in the width direction Y within the side region 27S. The outer end, in the width direction, of the side region 27S is defined as the absorbent member 23's end in the width direction.

[0031] The ratio (B/A) of the basis weight (B) of the adhesive in the side region 27S, where the side joined portions 27b are present, to the basis weight (A) of the adhesive in the central region 27C, where the central joined portions 27a are present, is preferably 1.3 or greater, more preferably 1.5 or greater, even more preferably 3.0 or greater, and preferably 100 or less, more preferably 80 or less, even more preferably 50 or less. More specifically, the ratio (B/A) of the basis weight (B) of the adhesive in the side region 27S, where the side joined portions 27b are present, to the basis weight (A) of the adhesive in the central region 27C, where the central joined portions 27a are present, is preferably from 1.3 to 100, more preferably from 1.5 to 80, even more preferably from 3.0 to 50. The basis weight of the adhesive in each region is determined based on the area of each region in a planar view. With this configuration, the rigidity of the side joined portions 27b can be further increased, thus enabling the pocket 1P for receiving feces to be formed more successfully.

[0032] From the same viewpoint, on condition that the aforementioned ratio is satisfied, the basis weight of the adhesive in the central region 27C, where the central joined portions 27a are present, is preferably 0.1 g/m2 or greater, more preferably 0.3 g/m2 or greater, even more preferably 0.5 g/m2 or greater, and preferably 10 g/m2 or less, more preferably 8 g/m2 or less, even more preferably 1 g/m2 or less. Similarly, on condition that the aforementioned ratio is satisfied, the basis weight of the adhesive in the side region 275, where the side joined portions 27b are present, is preferably 0.5 g/m2 or greater, more preferably 0.7 0/0-/n2 or greater, even more preferably 1 g/m2 or greater, and preferably 15 g/m2 or less, more preferably 10 g/m2 or less, even more preferably 2 g/m2 or less. The basis weight in each region can be measured by cutting out the region to be measured as a sample, and dividing the adhesive application amount (g) by the area (m2) of the sample in a planar view.

[0033] Preferably, as illustrated in Fig. 5, the number of side joined portions 27b extending in the longitudinal direction X is greater than the number of central joined portions 27a extending in the longitudinal direction X With this configuration, the rigidity of the side joined portions 27b can be further increased while allowing air to pass through the central area in the width direction, where there are relatively fewer joined portions 27. Thus, it is possible to achieve both easy formability of the pocket 1P and suppression of humidness/stuffiness when the diaper is worn.

[0034] Each of the joined portions 27 illustrated in Fig. 5 is formed like a streak along the longitudinal direction X, and may have, for example, a joining pattern having a certain width, such as a belt shape (stripe), spiral shape, or omega shape. Each joined portion 27 may be formed either continuously or non-continuously along the entire region in the longitudinal direction X of the outer-surface sheet 25.

[0035] Particularly as illustrated in Fig. 7, preferably, the joined portions 27 are formed intermittently in the longitudinal direction X. As regards the joined portions 27 illustrated in the figure, both the central joined portions 27a and the side joined portions 27b are intermittently formed, but only one of these joined portions may be formed intermittently.

With this configuration, it is possible to facilitate formation of the pocket 1P by increasing the rigidity of the side joined portions 27b, while also improving the softness of the diaper 1 itself [0036] Like the joined portions 27, it is also preferable that a plurality of second joined portions 27A are each formed in a belt shape or spiral shape along the longitudinal direction X. With this configuration, it is possible to further increase the rigidity of the absorbent member's side areas to thereby facilitate deformation of the absorbent member's central area, and thus easily form a pocket for retaining feces. As a result, excreta can be retained successfully by the pocket and leakage can be prevented.

[0037] From the viewpoint of easy formability of a pocket, it is preferable that the absorbent member 23 is formed as a single layer, and has the aforementioned low-basisweight portion 2L. An example of a configuration of an absorbent member 23 having a single layer and including a low-basis-weight portion 2L may be, for example, a configuration wherein the absorbent member 23 has a side surface as illustrated in Fig. 4(b) and the thickness of the absorbent member 23 gradually decreases.

[0038] Preferably, the shrinkage rate, in the longitudinal direction X, of the low-basis-weight portion 2L is higher than the shrinkage rate of other regions of the absorbent member 23. An example of such a configuration may be to employ an extensible absorbent member disclosed in e.g. JP 2009-136498A, wherein the shrinkage rate of the low-basisweight portion 2L is made different from other sections. With this configuration, it is possible to achieve both conformability to the wearer and deformability to excreta, and thereby prevent leakage of excreta.

[0039] As illustrated in Fig. 3, it is preferable that, in the thickness direction Z, the elastic member 29b in a stretched state is located overlapping the central region 27C where the central joined portions 27a are present. In cases where there are a plurality of elastic members 29b, it will suffice if at least one of the plurality of elastic members 29b overlaps the central region 27C, where the central joined portions 27a are present, in the thickness direction Z. With this configuration, the leak-proof cuffs formed by the respective intermediate sheets 29 can stand up even more favorably, and side leakage of excreta can be prevented [0040] Returning to Fig. 1, it is preferable that, in the thickness direction Z, at least one of the second elastic members 33, which are provided in the diaper l's below-waist portion W is arranged overlapping the low-basis-weight portion 2L of the absorbent member 23. Stated differently, in a spread-open and stretched state of the diaper 1 as illustrated in Fig. 2, it is preferable that the low-basis-weight portion 2L is present in a position within the diaper's rear portion R and where the second elastic members 33 are provided. With this configuration, three-dimensional deformation of the absorbent member 23 is further facilitated by the contraction of the second elastic members 33, thereby further preventing leakage of feces.

[0041] Particularly, it is preferable to cut, into a plurality of pieces, at least one of the second elastic members 33 present in a position overlapping the low-basis-weight portion 2L in the thickness direction, so as not to exhibit extensibility This process can be performed, for example, using an elastic-member cutting unit etc., which is used in a composite extensible member manufacturing method disclosed in e.g. JP 2002-253605A, by pressing the second elastic member(s) 33 corresponding to the position where the absorbent member 23's low-basis-weight portion 2L is arranged. With this configuration, it is possible to suppress excessive compression in the thickness direction due to contraction of the second elastic members 33, and further facilitate three-dimensional deformation of the absorbent member, thereby preventing leakage of excreta.

[0042] Further, it is preferable that both end portions of the second elastic member 33P that has been cut by being processed as above have an elastic member joined portion 35 joined by an adhesive, and, in the thickness direction Z, the elastic member joined portion 35 overlaps the side joined portion 27b. With this configuration, the rigidity of the absorbent member 23's side areas is further increased, and this further facilitates three-dimensional deformation of the absorbent member, thereby preventing leakage of feces effectively.

[0043] Further, it is preferable that the second elastic members 33 that have not been cut are located more toward the rear-side end portion IF side than the second elastic member 33P that has been cut, from the viewpoint of minimizing the gap between the wearer's rear (back) portion and the below-waist portion W in the rear portion R, and also facilitating three-dimensional deformation of the absorbent member 23 to prevent leakage of excreta in both the longitudinal direction and width direction.

[0044] Figs. 8 and 9 illustrate another embodiment of an absorbent member of a diaper according to the present invention. The following description focuses only on features that are different from those of the foregoing embodiment, and the explanation given above applies as appropriate to the other features. Further, members that are the same as those in the foregoing embodiment are accompanied by the same reference signs.

[0045] The diaper 1 illustrated in Fig. 8 includes an absorbent member 23 including a plurality of low-rigidity portions 2S extending along the longitudinal direction X. Each low-rigidity portion 2S illustrated in Fig. 9 includes no material forming the absorbent core 231 in the absorbent member 23, and is a through hole that penetrates the absorbent core in the thickness direction. Instead, the low-rigidity portion 2S may include a material forming the absorbent core 231 but may have a lower basis weight, or smaller thickness, than other regions of the absorbent member 23. In the thickness direction Z, each of the low-rigidity portions 2S and 2S is located overlapping the central joined portion 27a. The low-rigidity portions 2S illustrated in the figure are formed at least in the crotch portion NI of the absorbent member, and preferably extend up to the front portion F and the rear portion R beyond the crotch portion M. With this configuration, at the time of excretion, the absorbent member 23 can be deformed three-dimensionally, employing the low-rigidity portions 25 as axes for bending, and thus, a pocket capable of retaining excreta can be formed. As a result, feces can be retained in the absorbent member's central area even more successfully, and leakage can be prevented more effectively [0046] Preferably the width, in the width direction Y, of a single low-rigidity portion 2S is greater than the width, in the width direction Y, of a single joined portion 27 among the side joined portions 27b. Further, preferably, the width, in the width direction Y, of a single low-rigidity portion 2S is less than the total width, in the width direction Y, of the side joined portions 27b. With this configuration, it is possible to achieve both an improvement in the three-dimensional deformability of the absorbent member 23 and inhibition of unintended leakage of excreta through the low-rigidity portions 2S.

[0047] More specifically although dependent on the width and thickness of the absorbent member 23, the width W1 (see Fig. 9), in the width direction Y, of the low-rigidity portion 2S is preferably 0.5 mm or greater, more preferably 5 mm or greater, and preferably 20 mm or less, more preferably 15 mm or less. Further, it is preferable to form the side joined portions 27b such that the width, in the width direction Y, of each joined portion 27, among the side joined portions 27b, is preferably 0.5 mm or greater per single joined portion, more preferably 0.8 mm or greater, and preferably 5 mm or less, more preferably 2 mm or less.

[0048] As illustrated in Fig. 8, in a cross-sectional view along the diaper's width direction Y, it is preferable that the outer side edges 27L, in the width direction Y, of the central region 27C in which the central joined portions 27a are formed respectively overlap the low-rigidity portions 2S in the thickness direction. Stated differently, it is preferable that the boundary 27L between the central region 27C and each side region 27S overlaps the position of the respective low-rigidity portion 2S in the thickness direction. With this configuration, the absorbent member 23 can be deformed by substantially matching the positions of the low-rigidity portions 25 and the sections in the absorbent member 23 where the basis weight of the adhesive becomes different. Thus, the efficiency in forming the pocket by three-dimensional deformation of the absorbent member can be improved, and leakage of feces can be prevented effectively.

[0049] From the same viewpoint, as illustrated in Fig. 9, it is also preferable that the low-rigidity portions 2S are present at least in the low-basis-weight portion 2L. Stated differently, it is preferable that the low-rigidity portions 2S extend up to sections where the low-basis-weight portion 2L is present. As illustrated in the figure, it is also preferable that the high-basis-weight portion 2H is located more toward the outer side, in the diaper's longitudinal direction X, than the low-basis-weight portion 2L, and formed more toward the rear portion R side. With this configuration, it is possible to form a pocket three-dimensionally by the deformation of the low-basis-weight portion 2L, so that feces can be retained successfully and leakage in the wearer's front-rear direction can be prevented more effectively.

[0050] From the viewpoint of further facilitating three-dimensional formation of a pocket that can retain excreta in the absorbent member, and thereby preventing leakage, it is preferable that, in a cross-sectional view along the diaper's width direction Y, the ratio (T2/T1) of the length T2 from a center portion CL, in the width direction, of the absorbent member 23 to an outer side portion, in the width direction, of the low-rigidity portion 2S with respect to the length T1 from the center portion CL, in the width direction, of the absorbent member 23 to an end portion, in the width direction, of the absorbent member (see Fig. 9) is preferably 0.4 or greater, more preferably 0.5 or greater, even more preferably 0.6 or greater, and preferably 0.9 or less, more preferably 0.8 or less, even more preferably 0.7 or less. More specifically the ratio is preferably from 0.4 to 0.9, more preferably from 0.5 to 0.8, even more preferably from 0.6 to 0.7.

[0051] More specifically, the length T1 from the center portion CL, in the width direction, of the absorbent member 23 to the end portion thereof in the width direction is preferably 35 mm or greater, more preferably 50 mm or greater, and preferably 75 mm or less, more preferably 65 mm or less. Further, the length T2 from the absorbent member's center portion CL in the width direction to the outer end portion, in the width direction, of the low-rigidity portion 2S is preferably 20 mm or greater, more preferably 30 mm or greater, and preferably 50 mm or less, more preferably 40 mm or less.

[0052] A disposable diaper having the aforementioned configuration may be an open-type or pull-on disposable diaper. From the viewpoint of convenience of the wearer and helper when putting on the diaper, it is preferable that the diaper is of a pull-on type as illustrated in Figs. 1 and 6. In a pull-on disposable diaper, the outer cover 3 may be divided into a front outer cover and a rear outer cover, or instead, the outer cover 3 may be arranged spanning the front portion F up to the rear portion R via the crotch portion M. In either case, the disposable diaper of the present invention will have a good appearance immediately after putting on the diaper, whereas after excretion of excreta such as feces, a pocket 1P will be formed such that the absorbent member protrudes outward as illustrated in Fig. 6, and thus, the pocket IP will be able to absorb and retain feces and thereby suppress leakage of feces.

[0053] The present invention has been described above according to preferred embodiments thereof, but the present invention is not limited to the foregoing embodiments. For example, the low-rigidity portions 2S illustrated in Fig. 9 may be formed in the absorbent member 23 illustrated in Fig. 4(a) [0054] In relation to the foregoing embodiments of the present invention, the following pull-on disposable diapers and methods for manufacturing the same are further disclosed. {t} A disposable diaper comprising: an absorbent member; a non-skin-surface sheet arranged on a non-skin-facing surface side of the absorbent member; and an outer-surface sheet arranged on a non-skin-facing surface side of the non-skin-surface sheet, wherein: the disposable diaper includes a front portion to be arranged on a front side of a wearer in a state where the disposable diaper is worn, a crotch portion to be arranged in the wearer's crotch section, and a rear portion to be arranged on the wearer's rear side; the absorbent member includes a low-basis-weight portion in any position within a range from the crotch portion to the rear portion, the low-basis-weight portion having a basis weight relatively lower than other sections of the absorbent member; the outer-surface sheet and a sheet located on a skin-facing surface side of the outer-surface sheet are joined by an adhesive, and thereby, a plurality of joined portions extending in a longitudinal direction of the diaper are formed, the plurality of joined portions are located in a region overlapping the low-basis-weight portion in a thickness direction; and in this region, a basis weight of the adhesive in side regions located respectively in both side areas in a width direction of the diaper is higher than the basis weight of the adhesive in a central region located in a central area in the width direction.

[0055] The disposable diaper as set forth in clause {11, wherein a length of the joined portions along the diaper's longitudinal direction is longer than a length of the low-basisweight portion. {3)

The disposable diaper as set forth in clause {1} or {2}, wherein a ratio of the basis weight of the adhesive in the side region to the basis weight of the adhesive in the central region is from 1.3 to 100.

The disposable diaper as set forth in any one of clauses {1} to {3}, wherein the ratio of the basis weight of the adhesive in the side region to the basis weight of the adhesive in the central region is preferably 1.3 or greater, more preferably 1.5 or greater, even more preferably 3.0 or greater, and preferably 100 or less, more preferably 80 or less, even more preferably 50 or less.

The disposable diaper as set forth in clause;41, wherein, on condition that the aforementioned ratio is satisfied, the basis weight of the adhesive in the central region is preferably 0.1 g/m2 or greater, more preferably 0.3 g/m2 or greater, even more preferably 0.5 g/m2 or greater, and preferably 10 g/m2 or less, more preferably 8 g/m2 or less, even more preferably 1 g/m2 or less.

[0056] {6} The disposable diaper as set forth in clause {4) or {51, wherein, on condition that the aforementioned ratio is satisfied, the basis weight of the adhesive in the side region is preferably 0.5 g/m2 or greater, more preferably 0.7 g/m2 or greater, even more preferably 1 g/m2 or greater, and preferably 15 g/m2 or less, more preferably 10 g/m2 or less, even more preferably 2 g/m2 or less.

The disposable diaper as set forth in any one of clauses 111 to 161, wherein the number of the joined portions formed in the side region is greater than the number of the joined portions formed in the central region. {8)

The disposable diaper as set forth in any one of clauses 111 to 171, wherein the joined portion is formed intermittently in the diaper's longitudinal direction.

The disposable diaper as set forth in any one of clauses {1} to {81, wherein the absorbent member is single-layered.

[0057] The disposable diaper as set forth in any one of clauses {1} to {91, wherein the absorbent member includes a single low-basis-weight portion in the entire region, in the longitudinal direction and the width direction, of only the rear portion The disposable diaper as set forth in any one of clauses 111 to 1101, wherein the thickness of the low-basis-weight portion gradually decreases toward an end-side edge of the rear portion. {121

The disposable diaper as set forth in any one of clauses 111 to {111, wherein: the disposable diaper comprises an intermediate sheet located between the non-skin-surface sheet and the outer-surface sheet; a second joined portion is provided by joining the non-skin-surface sheet and the intermediate sheet with an adhesive; and a region in which the second joined portion is formed is located overlapping the side region in the thickness direction. { 13}

The disposable diaper as set forth in clause {12}, wherein: the intermediate sheet is provided in each of both side-portion areas in the diaper's width direction; and in the central area in the diaper's width direction, the outer-surface sheet is joined to the non-skin-surface sheet and thereby the joined portions are formed in the central region, and, in each of the side areas in the diaper's width direction, the outer-surface sheet is joined to the intermediate sheet and thereby the joined portions are formed in each of the side regions.

[0058] {14) The disposable diaper as set forth in clause 112f or 1131, wherein, in the thickness direction, the second joined portion is located overlapping the joined portions formed in the side region.

The disposable diaper as set forth in any one of clauses {12} to 1141, wherein a plurality of the second joined portions are each formed in a belt shape or spiral shape along the diaper's longitudinal direction.

The disposable diaper as set forth in any one of clauses 1121 to 15), wherein: the intermediate sheet's one side-portion area extending along the diaper's longitudinal direction is located between the non-skin-surface sheet and the outer-surface sheet, and the intermediate sheet's other side-portion area side is folded toward the skin-facing surface side of the absorbent member to form a leak-proof cuff; and an elastic member is provided in a stretched state to a free end of the leak-proof cuff 117) The disposable diaper as set forth in clause {16), wherein the elastic member in a stretched state is located overlapping the central region in the thickness direction [0059] { 18) The disposable diaper as set forth in any one of clauses {1) to 17), wherein: the absorbent member includes a plurality of low-rigidity portions extending along the longitudinal direction; and in the thickness direction, each of the low-rigidity portions overlaps the joined portion formed in the central region. 119)

The disposable diaper as set forth in clause {18), wherein a width of one of the low-rigidity portions is greater than a width of one of the joined portions formed in the side 20 region. )20}

The disposable diaper as set forth in clause {18) or {19), wherein the width of one of the low-rigidity portions is less than a total width of the joined portions formed in the side region. {21)

The disposable diaper as set forth in any one of clauses (18) to (20), wherein, in a cross-sectional view along the diaper's width direction, a ratio of a length from a center portion, in the width direction, of the absorbent member to an outer side portion, in the width direction, of the low-rigidity portion with respect to a length from the center portion, in the width direction, of the absorbent member to an end portion, in the width direction, of the absorbent member is from 0.4 to 0.9.

[0060] The disposable diaper as set forth in any one of clauses (18} to (211, wherein, in a cross-sectional view along the diaper's width direction, the ratio of the length from the center portion, in the width direction, of the absorbent member to the outer side portion thereof in the width direction, of the low-rigidity portion with respect to the length from the center portion, in the width direction, of the absorbent member to the end portion, in the width direction, of the absorbent member is preferably 0.4 or greater, more preferably 0.5 or greater, even more preferably 0.6 or greater, and preferably 0.9 or less, more preferably 0.8 or less, even more preferably 0.7 or less.

The disposable diaper as set forth in any one of clauses {18} to {22), wherein the length from the center portion, in the width direction, of the absorbent member to the end portion thereof in the width direction is preferably 35 mm or greater, more preferably 50 mm or greater, and preferably 75 mm or less, more preferably 65 mm or less.

The disposable diaper as set forth in any one of clauses {18} to {23}, wherein the length from the center portion, in the width direction, of the absorbent member to the outer end portion, in the width direction, of the low-rigidity portion 2S is preferably 20 mm or greater, more preferably 30 mm or greater, and preferably 50 mm or less, more preferably mm or less.

The disposable diaper as set forth in any one of clauses (18f to (241, wherein outer side edges of the joined portions formed in the central region respectively overlap the low-rigidity portions in the thickness direction.

[0061] The disposable diaper as set forth in any one of clauses {18} to {25}, wherein the low-rigidity portions are present at least in the low-basis-weight portion {27} The disposable diaper as set forth in any one of clauses {18} to {26), wherein no material forming an absorbent core in the absorbent member is present in the low-rigidity portions. { 281

The disposable diaper as set forth in any one of clauses {181 to {271, wherein the width, in the width direction, of the low-rigidity portion is preferably 0.5 mm or greater, more preferably 5 mm or greater, and preferably 20 mm or less, more preferably 15 mm or less.

The disposable diaper as set forth in any one of clauses {18) to {28}, wherein it is preferable that the low-rigidity portion extends up to a section where the low-basis-weight portion is present.

[0062] The disposable diaper as set forth in any one of clauses {11 to {291, wherein: the disposable diaper comprises an outer cover on a non-skin-facing surface side of the outer-surface sheet; the outer cover includes an inner-layer nonwoven fabric arranged on the non-skinfacing surface side of the outer-surface sheet, and an outer-layer nonwoven fabric arranged on a non-skin-facing surface side of the inner-layer nonwoven fabric; a plurality of second elastic members extending along the diaper's width direction are provided between the outer-layer nonwoven fabric and the inner-layer nonwoven fabric; and at least one of the second elastic members is arranged overlapping the low-basisweight portion in the thickness direction, and the second elastic members form waist gathers extending along the diaper's width direction. {31)

The disposable diaper as set forth in clause {301, wherein at least one of the second elastic members present in a position overlapping the low-basis-weight portion in the thickness direction is cut so as not to exhibit extensibility.

The disposable diaper as set forth in clause {30} or {31}, wherein: an elastic member joined portion is formed by joining, to the outer cover by an adhesive, both end portions of the second elastic member that has been cut; and in the thickness direction, the elastic member joined portion overlaps the joined portion formed in the side region The disposable diaper as set forth in any one of clauses {30} to {32}, wherein the second elastic member that has not been cut is located more toward the rear-side end portion than the second elastic member that has been cut.

The disposable diaper as set forth in any one of clauses {1} to 133), wherein the absorbent member includes a high-basis-weight portion having a higher basis weight than the low-basis-weight portion, the high-basis-weight portion being located more toward the rear side than the low-basis-weight portion. 13'5}

The disposable diaper as set forth in any one of clauses 11} to 1341, wherein a shrinkage rate, in the diaper's longitudinal direction, of the low-basis-weight portion is higher than the shrinkage rate of other regions of the absorbent member. In

The disposable diaper as set forth in any one of clauses {1} to {35}, wherein: the central region is formed within a range from 40 to 70%, with respect to an entire length of the absorbent member in the width direction, spanning both sides of the center portion of the absorbent member; and each of the side regions is formed within a range from 15 to 30%, with respect to the entire length of the absorbent member in the width direction, from one of both lateral side edges of the absorbent member.

[0063] {37} The disposable diaper as set forth in any one of clauses {1} to 1361, wherein: the disposable diaper comprises an outer cover on the non-skin-facing surface side of the outer-surface sheet; the outer cover is divided into a rear outer cover to be arranged on the wearer's rear side, and a front outer cover to be arranged on the wearer's front side; and an absorbent assembly including the absorbent member is fixed so as to bridge the rear outer cover and the front outer cover.

The disposable diaper as set forth in any one of clauses 1 to {37}, wherein the disposable diaper is a pull-on diaper.

Industrial Applicability

[0064] The present invention provides a disposable diaper capable of preventing leakage of excreta, without impairing the appearance when the diaper is worn

Claims

CLAIMS[Claim 1] A disposable diaper comprising: an absorbent member; a non-skin-surface sheet arranged on a non-skin-facing surface side of the absorbent member; and an outer-surface sheet arranged on a non-skin-facing surface side of the non-skinsurface sheet, wherein: the disposable diaper includes a front portion to be arranged on a front side of a wearer in a state where the disposable diaper is worn, a crotch portion to be arranged in the wearer's crotch section, and a rear portion to be arranged on the wearer's rear side; the absorbent member includes a low-basis-weight portion in any position within a range from the crotch portion to the rear portion, the low-basis-weight portion having a basis weight relatively lower than other sections of the absorbent member; the outer-surface sheet and a sheet located on a skin-facing surface side of the outer-surface sheet are joined by an adhesive, and thereby, a plurality of joined portions extending in a longitudinal direction of the diaper are formed, the plurality of joined portions are located in a region overlapping the low-basisweight portion in a thickness direction; and in this region, a basis weight of the adhesive in side regions located respectively in both side areas in a width direction of the diaper is higher than the basis weight of the adhesive in a central region located in a central area in the width direction.[Claim 2] The disposable diaper according to claim 1, wherein a length of the joined portions along the diaper's longitudinal direction is longer than a length of the low-basisweight portion.[Claim 3] The disposable diaper according to claim 1 or 2, wherein a ratio of the basis weight of the adhesive in the side region to the basis weight of the adhesive in the central region is from 1.3 to 100.[Claim 4] The disposable diaper according to any one of claims Ito 3, wherein the number of the joined portions formed in the side region is greater than the number of the joined portions formed in the central region.[Claim 5] The disposable diaper according to any one of claims Ito 4, wherein the joined portion is formed intermittently in the diaper's longitudinal direction [Claim 6] The disposable diaper according to any one of claims 1 to 5, wherein the absorbent member is single-layered.[Claim 7] The disposable diaper according to any one of claims Ito 6, wherein: the disposable diaper comprises an intermediate sheet located between the nonskin-surface sheet and the outer-surface sheet; a second joined portion is provided by joining the non-skin-surface sheet and the intermediate sheet with an adhesive; and a region in which the second joined portion is formed is located overlapping the side region in the thickness direction.[Claim 8] The disposable diaper according to claim 7, wherein: the intermediate sheet is provided in each of both side-portion areas in the diaper's width direction; and in the central area in the diaper's width direction, the outer-surface sheet is joined to the non-skin-surface sheet and thereby the joined portions are formed in the central region, and, in each of the side areas in the diaper's width direction, the outer-surface sheet is joined to the intermediate sheet and thereby the joined portions are formed in each of the side regions.[Claim 9] The disposable diaper according to claim 7 or 8, wherein, in the thickness direction, the second joined portion is located overlapping the joined portions formed in the side region.[Claim 10] The disposable diaper according to any one of claims 7 to 9, wherein a plurality of the second joined portions are each formed in a belt shape or spiral shape along the diaper's longitudinal direction.[Claim 11] The disposable diaper according to any one of claims 7 to 10, wherein: the intermediate sheet's one side-portion area extending along the diaper's longitudinal direction is located between the non-skin-surface sheet and the outer-surface sheet, and the intermediate sheet's other side-portion area side is folded toward the skin-facing surface side of the absorbent member to form a leak-proof cuff, and an elastic member is provided in a stretched state to a free end of the leak-proof cuff.[Claim 12] The disposable diaper according to claim 11, wherein the elastic member in a stretched state is located overlapping the central region in the thickness direction.[Claim 13] The disposable diaper according to any one of claims Ito 12, wherein: the absorbent member includes a plurality of low-rigidity portions extending along the longitudinal direction; and in the thickness direction, each of the low-rigidity portions overlaps the joined portion formed in the central region.[Claim 14] The disposable diaper according to claim 13, wherein a width of one of the low-rigidity portions is greater than a width of one of the joined portions formed in the side region.[Claim 15] The disposable diaper according to claim 13 or 14, wherein the width of one of the low-rigidity portions is less than a total width of the joined portions formed in the side region.[Claim 16] The disposable diaper according to any one of claims 13 to 15, wherein, in a cross-sectional view along the diaper's width direction, a ratio of a length from a center portion, in the width direction, of the absorbent member to an outer side portion, in the width direction, of the low-rigidity portion with respect to a length from the center portion, in the width direction, of the absorbent member to an end portion, in the width direction, of the absorbent member is from 0.4 to 0.9.[Claim 17] The disposable diaper according to any one of claims 13 to 16, wherein outer side edges of the joined portions formed in the central region respectively overlap the low-rigidity portions in the thickness direction.[Claim 18] The disposable diaper according to any one of claims 13 to 17, wherein the low-rigidity portions are present at least in the low-basis-weight portion.[Claim 19] The disposable diaper according to any one of claims Ito 18, wherein: the disposable diaper comprises an outer cover on a non-skin-facing surface side of the outer-surface sheet; the outer cover includes an inner-layer nonwoven fabric arranged on the non-skin-facing surface side of the outer-surface sheet, and an outer-layer nonwoven fabric arranged on a non-skin-facing surface side of the inner-layer nonwoven fabric, a plurality of second elastic members extending along the diaper's width direction are provided between the outer-layer nonwoven fabric and the inner-layer nonwoven fabric; 15 and at least one of the second elastic members is arranged overlapping the low-basisweight portion in the thickness direction, and the second elastic members form waist gathers extending along the diaper's width direction.[Claim 20] The disposable diaper according to claim 19, wherein at least one of the second elastic members present in a position overlapping the low-basis-weight portion in the thickness direction is cut so as not to exhibit extensibility.[Claim 21] The disposable diaper according to claim 20, wherein: an elastic member joined portion is formed by joining, to the outer cover by an adhesive, both end portions of the second elastic member that has been cut; and in the thickness direction, the elastic member joined portion overlaps the joined portion formed in the side region. 3][Claim 22] The disposable diaper according to claim 20 or 21, wherein the second elastic member that has not been cut is located more toward the rear-side end portion than the second elastic member that has been cut.[Claim 23] The disposable diaper according to any one of claims Ito 22, wherein the absorbent member includes a high-basis-weight portion having a higher basis weight than the low-basis-weight portion, the high-basis-weight portion being located more toward the rear side than the low-basis-weight portion.[Claim 24] The disposable diaper according to any one of claims Ito 23, wherein a shrinkage rate, in the diaper's longitudinal direction, of the low-basis-weight portion is higher than the shrinkage rate of other regions of the absorbent member.[Claim 25] The disposable diaper according to any one of claims Ito 24, wherein: the central region is formed within a range from 40 to 70%, with respect to an entire length of the absorbent member in the width direction, spanning both sides of the center portion of the absorbent member; and each of the side regions is formed within a range from 15 to 30%, with respect to the entire length of the absorbent member in the width direction, from one of both lateral side edges of the absorbent member.[Claim 26] The disposable diaper according to any one of claims 1 to 25, wherein the disposable diaper is a pull-on diaper.