GB2559714A

GB2559714A - Underpants-type disposable diaper

Info

Publication number: GB2559714A
Application number: GB1809269.2A
Authority: GB
Inventors: Fukuda Yuko
Original assignee: Kao Corp
Current assignee: Kao Corp
Priority date: 2015-11-20
Filing date: 2016-10-19
Publication date: 2018-08-15
Anticipated expiration: 2036-10-19
Also published as: JP6180605B2; CN108289770A; GB201809269D0; CN108289770B; RU2677078C1; JP2017099854A; DE112016005342B4; DE112016005342T5; GB2559714B

Abstract

According to the present invention, an exterior body (3) has an exterior body contraction region (35) in which waistline elastic members (5) are disposed intermittently in a longitudinal direction (X), between an outer layer sheet (31) and an inner layer sheet (32) of an extension and contraction section that can extend and contract in a lateral direction (Y), in a state where the waistline elastic members (5) are extended in the lateral direction (Y). Ridges (36) and grooves (37) that extend in the longitudinal direction (X) are alternately disposed in the lateral direction (Y) on the skin-facing surface side of the exterior body contraction region (35). The sheets (31, 32) have, in the exterior body contraction region (35), through-holes (33) formed in the grooves (37) that are located outward of the end portion, in the longitudinal direction, of an absorbent body (23). A plurality of recesses (211) which extend in the longitudinal direction (X), and a plurality of protrusions (210) are formed in a skin-facing surface of a surface sheet (2) such that the recesses (211) are located at the same positions as the grooves (37) in the lateral direction (Y).

Description

(56) Documents Cited:

WO 2009/031393 A1 WO2015146704 US2007029671 WO2016013448

A61F 13/494(2006.01) A61F 13/511 (2006.01)

JP 2009118986 A (86) International Application Data:

PCT/JP2016/081000 Ja 19.10.2016 (58) Field of Search:

INT CL A61F, A61L (87) International Publication Data:

WO2017/086081 Ja 26.05.2017 (71) Applicant(s):

Kao Corporation (Incorporated in Japan)

14-10 Nihonbashi Kayabacho-1 -chome, Chuo-ku, Tokyo 103-8210, Japan (72) Inventor(s):

Yuko Fukuda (74) Agent and/or Address for Service:

Withers & Rogers LLP

More London Riverside, LONDON, SE1 2AU, United Kingdom (54) Title of the Invention: Underpants-type disposable diaper Abstract Title: Underpants-type disposable diaper (57) According to the present invention, an exterior body (3) has an exterior body contraction region (35) in which waistline elastic members (5) are disposed intermittently in a longitudinal direction (X), between an outer layer sheet (31) and an inner layer sheet (32) of an extension and contraction section that can extend and contract in a lateral direction (Y), in a state where the waistline elastic members (5) are extended in the lateral direction (Y). Ridges (36) and grooves (37) that extend in the longitudinal direction (X) are alternately disposed in the lateral direction (Y) on the skin-facing surface side of the exterior body contraction region (35). The sheets (31, 32) have, in the exterior body contraction region (35), through-holes (33) formed in the grooves (37) that are located outward of the end portion, in the longitudinal direction, of an absorbent body (23). A plurality of recesses (211) which extend in the longitudinal direction (X), and a plurality of protrusions (210) are formed in a skin-facing surface of a surface sheet (2) such that the recesses (211) are located at the same positions as the grooves (37) in the lateral direction (Y).

This international application has entered the national phase early.

1/7

Fig. 1

S(A1,C1)

3(31)

S(A2,C2)

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Fig. 2

3X ²?° 31E(3)

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1B

1C

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Fig. 3

Y

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Fig. 4

1(1 A) ^31E<³> 21E _ \ oy i 6

(35)

Fig.5

23(230)

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Fig. 7

6/7

Fig. 8

35(3)

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—

DESCRIPTION

Title of Invention: UNDERPANTS-TYPE DISPOSABLE DIAPER

Technical Field [0001]

The present invention relates to a pull-on disposable diaper in which a waist opening and a pair of leg openings are formed.

Background Art [0002]

Conventionally, a pull-on disposable diaper is known that includes: an absorbent assembly that includes a liquid-retainable absorbent member and a top sheet that is provided on a skin-facing surface side of the absorbent member; and an outer cover that is provided on a non-skin-facing surface side of the absorbent assembly and fixes the absorbent assembly, wherein the outer cover has a stacked structure including an inner layer sheet that is bonded to the absorbent assembly, and an outer layer sheet that is bonded to a non-skin-facing surface of the inner layer sheet. As the outer cover, from the viewpoint of improving the fit of the diaper and the like, there are cases of using a stretchable sheet that is stretchable in a direction (the lateral direction of the diaper) perpendicular to the front-back direction (the longitudinal direction of the diaper) of a wearer wearing the diaper.

[0003]

For example, Patent Literature 1 discloses a pull-on disposable diaper that has a configuration as described above, wherein a plurality of below-waist elastic members that are stretched out in the lateral direction are provided in a portion that corresponds to the waist of the wearer and are provided between the inner layer sheet and the outer layer sheet, and some of the plurality of below-waist elastic members are provided so as to overlap a longitudinal end portion of an absorbent core as viewed in a plan view. The arrangement of the below-waist elastic members described above is advantageous in that the area where the longitudinal end portion of the absorbent core is located is likely to come into close contact with the skin of the wearer, which prevents liquid leakage and the like. Patent Literature 1 is designed primarily to overcome the problem of wrinkles occurring in the absorbent core due to the arrangement of the below-waist elastic members described above, and thus the specific means for solving the problem is directed to the absorbent core. Accordingly, Patent Literature 1 does not specifically disclose a problem regarding permeability, an improvement in the top sheet to address the problem, and the like.

[0004]

Patent Literature 2 discloses a disposable diaper in which a sheet that has protrusions and depressions that are formed by alternately providing protruding portions having a relatively high basis weight and depressed portions having a low basis weight is provided as the top sheet such that the protruding portions are on the skin side. In this top sheet, a waste liquid such as urine flows into groove portions that have a low basis weight and is rapidly absorbed. Patent Literature 2 also discloses the following advantages: the rigidity of the sides of the protruding portions is high because the fibers are tightly packed. Because the center portions sandwiched between the sides of the protruding portions contain a lot of fibers oriented in the thickness direction, the protruding portions are unlikely to be easily crushed even under additional weight. However, Patent Literature 2 does not provide any means for solving a problem, caused by the grooves of the depressed portions of this structure, that a gap is created between the diaper and the skin, and a waste liquid such as urine is likely to leak out.

Citation List

Patent Literature [0005]

Patent Literature 1: JP 2013-255561 A

Patent Literature 2: US 2007298671 Al

Summary of Invention [0006]

The present invention relates to a pull-on disposable diaper including: a front portion that is to be placed on an abdominal side of a wearer, a rear portion that is to be placed on a dorsal side of the wearer, and a crotch portion that is provided between the front portion and the rear portion, the pull-on disposable diaper having a longitudinal direction that extends from the front portion to the rear portion via the crotch portion, and a lateral direction that is perpendicular to the longitudinal direction, and the pull-on disposable diaper further including: an absorbent assembly including an absorbent member and a top sheet that is provided on a skin-facing surface side of the absorbent member; and an outer cover that is provided on a non-skin-facing surface side of the absorbent assembly, and fixes the absorbent assembly, and both lateral side edge portions of the outer cover in the front portion and both lateral side edge portions of the outer cover in the rear portion being bonded to form a waist opening and a pair of leg openings.

The outer cover includes an outer layer sheet that is located on a side that is relatively far from the absorbent assembly and an inner layer sheet that is located on a side that is relatively close to the absorbent assembly, and further includes a stretchable portion in at least one of the front portion and the rear portion, the stretchable portion being stretchable in the lateral direction.

A plurality of below-waist elastic members that are stretched out in the lateral direction are provided intermittently in the longitudinal direction between the outer layer sheet and the inner layer sheet in the stretchable portion, such that a portion of the plurality of below-waist elastic members pass through an overlapping portion that overlaps a longitudinal end portion of the absorbent member and cross the longitudinal end portion in the lateral direction as viewed in a plan view.

The stretchable portion shrinks in the lateral direction due to shrinkage of the below-waist elastic members in the stretchable portion so as to form an outer cover shrinkable region, and the outer cover shrinkable region has, on the skin-facing surface side, an uneven structure in which ridge portions and groove portions that extend in the longitudinal direction are alternately provided in the lateral direction.

At least one of the outer layer sheet and the inner layer sheet in the outer cover shrinkable region includes through holes that extend therethrough in a thickness direction thereof in the groove portions that are present on an outer side in the longitudinal direction of the longitudinal end portion of the absorbent member.

On the skin-facing surface of the top sheet, a plurality of projections that protrude toward the skin of the wearer, and a plurality of depressions that are located between the projections that are adjacent in the lateral direction and extend in the longitudinal direction are formed such that at least some of the plurality of depressions are at the same positions in the lateral direction as the groove portions in the outer cover shrinkable region.

Brief Description of Drawings [0007] [Fig. 1] Fig. 1 is a perspective view schematically showing a pull-on disposable diaper according to an embodiment of the present invention.

[Fig. 2] Fig. 2 is a flat-out plan view schematically showing a skin-facing surface side (inner surface side) of the diaper shown in Fig. 1 in its flat-out and uncontracted state.

[Fig. 3] Fig. 3 is a disassembled perspective view schematically showing the diaper shown in Fig. 1 in its disassembled state.

[Fig. 4] Fig. 4 is a vertical cross-sectional view schematically showing a cross section taken along the line I-I shown in Fig. 2.

[Fig. 5] Fig. 5 is a horizontal cross-sectional view schematically showing a cross section taken along the line II-II shown in Fig. 2.

[Fig. 6] Fig. 6 is a horizontal cross-sectional view schematically showing a cross section taken along the line I-I shown in Fig. 2 when the diaper shown in Fig. 1 is in its natural state or worn state.

[Fig. 7] Fig. 7 is a perspective view schematically showing a longitudinal end portion of an absorbent assembly and the vicinity thereof when the diaper shown in Fig. 1 is in its natural state or worn state.

[Fig. 8] Fig. 8 is a perspective view schematically showing an outer cover shrinkable region when the diaper shown in Fig. 1 is in its natural state or worn state.

[Fig. 9] Fig. 9 is a plan view schematically showing an outer cover of the diaper shown in Fig. 1.

[Fig. 10] Fig. 10 is a partially cut-away perspective view schematically showing an example of an outer layer sheet that constitutes the outer cover of the diaper shown in Fig. 1.

Description of Embodiments [0008]

In a disposable diaper, a waste liquid such as urine that has been absorbed and retained in the absorbent member evaporates from the skin-facing surface side due to the body temperature of the wearer, and is discharged toward the skin of the wearer as water vapor, as a result of which, the interior space of the worn diaper, or in other words, the space between the wearer's skin and the skin-facing surface of the diaper is built-up with moisture, which may cause skin issues such as itchiness and a rash. In particular, with a pull-on disposable diaper as disclosed in Patent Fiterature 1 that includes below-waist elastic members that are stretchable in the lateral direction, when the outer cover shrinks in the lateral direction due to shrinkage of the below-waist elastic members when the diaper is worn, the absorbent assembly fixed to the outer cover, in particular, an overlapping portion that overlaps the below-waist elastic members as viewed in a plan view also shrinks in the lateral direction and comes into contact with the skin of the wearer, which hinders the transfer of water vapor in the longitudinal direction of the diaper, and makes it difficult for the water vapor to be discharged to the outside via the waist opening, as a result of which a build-up of moisture may be induced. As a method for preventing the hindrance of air permeability caused by the shrinkage of the absorbent assembly as described above, a method may be conceived in which, for example, the overlapping portion of the below-waist elastic members that is overlapped by the absorbent assembly as viewed in a plan view is cut so as to suppress the stretchability of the below-waist elastic members in the lateral direction. However, with this method, the absorbent assembly may be separated upward from the outer cover, and as a result of the absorbent assembly being separated upward from the outer cover, not only discharge of water vapor, which is the cause of a build-up of moisture, is inhibited, but also leakage of a waste liquid may be induced.

[0009]

Accordingly, the present invention is intended to provide a pull-on disposable diaper that has excellent air permeability, and can prevent leakage of a waste liquid while effectively preventing a build-up of moisture and skin issues.

[0010]

Hereinafter, the present invention will be described by way of a preferred embodiment of the present invention with reference to the drawings. Figs. 1 to 7 show a schematic configuration of a pull-on disposable diaper 1 that is a pull-on disposable diaper according to an embodiment of the present invention, and a configuration of relevant parts thereof. The diaper 1 includes a front portion 1A that is to be placed on an abdominal side of a wearer, a rear portion 1C that is to be placed on a dorsal side of the wearer, and a crotch portion IB that is provided between the front portion 1A and the rear portion 1C. The diaper 1 also has a longitudinal direction X that extends from the front portion lAto the rear portion 1C via the crotch portion IB, and a lateral direction Y that is perpendicular to the longitudinal direction X.

[0011]

The diaper 1 includes: an absorbent assembly 2 that includes an absorbent member 23 and a top sheet 21 that is provided on the skin-facing surface side of the absorbent member 23; and an outer cover 3 that is located on the non-skin-facing surface side of the absorbent assembly 2, and fixes the absorbent assembly 2. Both lateral side edge portions of the outer cover 3 in the front portion 1A that extend in the longitudinal direction X and both lateral side edge portions of the outer cover 3 in the rear portion 1C that extend in the longitudinal direction X are bonded together so as to form a pair of side seal portions S and S, as well as a waist opening WH that goes around the waist of the wearer, and a pair of leg openings LH and LH through which the legs of the wearer are passed.

[0012]

In this specification, the term skin-facing surface refers to a surface of a disposable diaper or a constituent member thereof (for example, the top sheet) that is provided to face the skin side of the wearer when the diaper is worn, or in other words, a side that is relatively close to the skin of the wearer. Likewise, the term non-skin-facing surface refers to a surface of a disposable diaper or a constituent member thereof that is provided to face the side (garment side) opposite to the skin of the wearer when the diaper is worn, or in other words, a surface that is relatively far from the skin of the wearer. As used herein, the expression when a disposable diaper is worn means a normal and properly worn position, or in other words, a state in which the correctly worn position of the disposable diaper is maintained, and does not encompass a state in which the disposable diaper is out of the correctly worn position.

[0013]

The front portion lAand the rear portion 1C are each portions that are provided at the same positions in the longitudinal direction X as the side seal portions S, and are below-waist portions that are to be placed around the waist of the wearer when the diaper 1 is worn. The crotch portion IB is a region where recesses for forming the leg openings LH and LH are formed on both side edge portions of the outer cover 3 that extend in the longitudinal direction X. The crotch portion IB includes a waste discharging portion-facing portion that is to be placed facing the waste discharging portion of the wearer when the diaper 1 is worn, and the waste discharging portion-facing portion is normally provided at or near the center of the diaper 1 in the longitudinal direction X.

[0014]

As indicated by a contour line in Fig. 2, the absorbent assembly 2 has an elongated rectangular shape as viewed in a plan view. The absorbent assembly 2 is fixed at the center of the outer cover 3 in the lateral direction Y, with its lengthwise direction coinciding with the longitudinal direction X of the diaper 1 in its flat-out and uncontracted state. The outer cover 3 forms an outer contour of the diaper 1 in its flat-out and uncontracted state as shown in Fig. 2, and the peripheral edge of the outer cover 3 forms a contour line of the diaper 1 in the flat-out and uncontracted state. As used herein, the expression flat-out and uncontracted state of the diaper 1 refers to a state in which the diaper 1 is unfolded by separating the side seal portions S, and the unfolded diaper 1 is stretched out to design dimensions (which are the same as the dimensions of the diaper when it is flattened out, without considering the influence of the elastic members) by extending the elastic members of the constituent members.

[0015]

The absorbent assembly 2 includes a liquid-permeable top sheet 21 that forms the skin-facing surface, a liquid-impermeable or liquid less-permeable, or water-repellent back sheet 22 that forms the non-skin-facing surface, and a liquid-retainable absorbent member 23 that is provided between the both sheets 21 and 22. These are bonded using a known bonding means such as an adhesive to form an integrated structure. The absorbent member 23 is located at the center of the diaper 1 (the outer cover 3) in the lateral direction Y. As the top sheet 21 and back sheet 22, any type of sheet that is conventionally used in this type of absorbent article can be used without any limitation. For example, a non-woven fabric, a porous film, or the like can be used as the top sheet 21, and a resin film, a laminate of a resin film and a non-woven fabric, or the like can be used as the back sheet 22.

[0016]

As viewed in a plan view as shown in Fig. 2, the absorbent member 23 has a substantially elongated rectangular shape in the longitudinal direction X, and extends from the front portion lAto the rear portion 1C. The absorbent member 23 includes a liquid-retainable absorbent core 24 that contains an absorbent material, and a core wrap sheet 25 that covers the skin-facing surface and the non-skin-facing surface of the absorbent core 24. The absorbent core 24 and the core wrap sheet 25 are bonded using a known bonding means such as a hot melt adhesive.

[0017]

The absorbent core 24 has a monolayer structure, and is formed by stacking fibers of a core forming material that contains an absorbent material. As the absorbent material, any absorbent material that is conventionally used to form this type of absorbent core can be used without any particular limitation. For example, it is possible to use wood pulp, hydrophilic fibers such as synthetic fibers that have been treated with a hydrophilizing agent, and absorbent polymer particles. That is, the absorbent core 24 may be made of a fiber stack made of hydrophilic fibers, or absorbent polymer particles that are supported by the fiber stack. As the core wrap sheet 25, a water-permeable sheet material can be used. It is possible to use, for example, paper, a non-woven fabric, and the like.

[0018]

As shown in Figs. 2 and 5, on both lateral side portions of the skin-facing surface of the absorbent assembly 2 that extend in the longitudinal direction X, a pair of anti-leak cuffs 28 and 28 are provided that are made of a sheet material that is liquid resistant or water-repellent and air-permeable. One or more (one in the present embodiment) anti-leak cuff-forming elastic members 29 in the form of a thread is provided in a stretched-out state near a free end portion of each anti-leak cuff 28. The anti-leak cuffs rise upward at least in the crotch portion IB due to shrinkage of the elastic members provided in a stretched-out state, when the diaper 1 is worn, and thereby prevent a waste liquid such as urine from flowing outward in the lateral direction Y.

[0019]

As shown in Fig. 2, the outer cover 3 is provided so as to extend across the front portion 1A that corresponds to the below-waist portion of the front body portion, the rear portion 1C that corresponds to the below-waist portion of the back body portion, and the crotch portion IB that is provided between the front portion 1A and the rear portion 1C. Both side edges that extend in the longitudinal direction X are each curved to form an inward arc in the crotch portion IB, and thereby form a pair of leg edge portions. As shown in a plan view in Fig. 2, the outer cover 3 has an hourglass shape in which the center region in the longitudinal direction X is curved inward in the lateral direction Y. In the outer cover 3, both lateral side edge portions Al and A2 of the front portion 1A that extend in the longitudinal direction X, and both lateral side edge portions Cl and C2 of the rear portion 1C that extend in the longitudinal direction X are bonded to each other using a known bonding means such as an adhesive, heat sealing, or ultrasonic sealing. As a result of bonding, as shown in Fig. 1, a pair of side seal portions S and S, as well as a waist opening WH and a pair of leg openings FH and FH are formed in the diaper 1. In an area of the outer cover 3 that forms an opening edge portion for a leg opening FH, a leg elastic member 4 for forming leg gathers is provided in a stretched-out state. The leg elastic member 4 is in the form of a thread or strip, and is provided between an outer layer sheet 31 and an inner layer sheet 32 that constitute the outer cover 3, and is fixed therebetween using an adhesive.

[0020]

As shown in Figs. 3 to 5, the outer cover 3 includes an outer layer sheet 31 that is located on the side that is relatively far from the absorbent assembly 2, and an inner layer sheet 32 that is located on the side that is relatively close to the absorbent assembly 2. When the diaper 1 is worn, the inner layer sheet 32 is located on the side close to the body of the wearer, and forms the skin-facing surface (inner surface) of the diaper 1. The outer layer sheet 31 is located on the side far from the body of the wearer, and forms the non-skin-facing surface (outer surface) of the diaper 1. The outer layer sheet 31 and the inner layer sheet 32 are bonded to each other at a predetermined region using a known bonding means such as an adhesive.

[0021]

The outer layer sheet 31 further includes, in addition to a portion that has the same shape and dimensions as those of the inner layer sheet 32, a front extension portion 3 IE that extends outward from an end portion in the longitudinal direction X on the front portion IA side of the inner layer sheet 32 when the both sheets 31 and 32 are stacked, and a rear extension portion 3 IE that extends outward from an end portion in the longitudinal direction X on the rear portion 1C side of the inner layer sheet 32. As shown in Fig. 2, the both extension portions 3 IE and 3 IE of the outer layer sheet 31 are folded over the inner layer sheet 32 so as to respectively cover both end portions of the absorbent assembly 2 in the longitudinal direction X that is fixedly provided on the inner layer sheet 32, and are fixed with an adhesive to other constituent members (the inner layer sheet 32, the absorbent assembly 2, and the anti-leak cuffs 28) of the diaper 1 that face the both extension portions 3 IE and 3 IE. The extension portions 3 IE of the outer layer sheet 31 function as hydrophobic sheets, which will be described later.

[0022]

The outer cover 3 includes, in at least one of the front portion IA and the rear portion 1C, a stretchable portion that is stretchable in the lateral direction Y. As used herein, a stretchable portion of the outer cover refers to an area of the outer cover 3 that is stretchable in the lateral direction Y, and in the present embodiment, a portion of the outer cover 3 that is located in the front portion 1A and a portion of the outer cover 3 that is located in the rear portion 1C are stretchable portions. To be more specific, in the present embodiment, the outer layer sheet 31 and the inner layer sheet 32 that constitute the outer cover 3 are non-stretchable sheets that are not stretchable. However, in each of the front portion IA and the rear portion 1C, as will be described later, a plurality of below-waist elastic members 5 that are stretched out in the lateral direction Y are provided between the both sheets 31 and 32. Accordingly, due to the stretchability in the lateral direction Y of the plurality of below-waist elastic members 5, the entire area of each of the portion of the outer cover 3 that is located in the front portion 1 A and the portion of the outer cover 3 that is located in the rear portion 1C is stretchable in the lateral direction Y, and thus referred to as the stretchable portion.

[0023]

As shown in Figs. 2 to 4, in the above-described stretchable portions, or in other words, in the portion of the outer cover 3 that is located in the front portion 1A and the portion of the outer cover 3 that is located in the rear portion 1C, a plurality of below-waist elastic members 5 that are stretched out in the lateral direction Y are provided intermittently in the longitudinal direction X between the outer layer sheet 31 and the inner layer sheet 32. As viewed in a plan view, a portion of the plurality below-waist elastic members 5 pass through a portion that is overlapped by a longitudinal end portion 230 of the absorbent member 23, and cross the longitudinal end portion 230 in the lateral direction Y. More specifically, in each of the front portion 1A and the rear portion 1C, a longitudinal end 2X of the absorbent assembly 2 is present at a position inward in the longitudinal direction X of a longitudinal end 3X (i.e., the opening edge of the waist opening WH) of the outer cover 3. That is, each of the front portion 1A and the rear portion 1C is divided in the longitudinal direction X into an absorbent assembly-absent region 10 that is located on the outermost side in the longitudinal direction X, and an absorbent assembly-present region 11 that is located on the inner side of the region 10 in the longitudinal direction X. The below-waist elastic members 5 are provided in each of the regions 10 and 11. Each longitudinal end portion 230 of the absorbent member 23 is an area that includes a longitudinal end that forms a portion of the contour of the absorbent member 23, and the vicinity of the longitudinal end. In the present embodiment, as shown in Fig. 4, the longitudinal end of the absorbent member 23 is provided at the same position in the longitudinal direction X as the longitudinal end 2X of the absorbent assembly 2.

[0024]

When the diaper 1 is in its natural state or worn state, as shown in Figs. 6 and 7, due to shrinkage of the below-waist elastic members 5 in the stretchable portions, or in other words, each of the portion of the outer cover 3 that is located in the front portion 1A and the portion of the outer cover 3 that is located in the rear portion 1C, the stretchable portions shrink in the lateral direction Y, and an outer cover shrinkable region 35 is thereby formed, and on the skin-facing surface side of the outer cover shrinkable region 35, an uneven structure is formed in which ridge portions 36 and groove portions 37 that extend in the longitudinal direction X are alternately provided in the lateral direction Y. That is, the outer cover shrinkable region 35 is an above-described stretchable portion. In Figs. 6 and 7, only the front portion 1A is shown, but an outer cover shrinkable region 35 is also formed in the rear portion 1C in the same manner as in the front portion 1A. In the configuration shown Fig. 5 that shows the same area as that shown in Fig. 6 and that is a diagram showing a portion of the diaper 1 in a flat-out and uncontracted state shown in Fig. 2, the outer cover 3 and the below-waist elastic members 5 are stretched out in the lateral direction Y, and thus the outer cover shrinkable region 35 is not formed.

[0025]

In each of the front portion 1A and the rear portion 1C, the outer cover shrinkable region 35 is formed at least in the region where the below-waist elastic members 5 are disposed. In the present embodiment, the outer cover shrinkable region 35 is formed over the absorbent assembly-absent region 10 and the absorbent assembly-present region 11, and as shown in Fig. 6, is also formed in the overlapping area of the absorbent assembly-present region 11 that is overlapped by the absorbent assembly 2 as viewed in a plan view. In the front portion 1A and the rear portion 1C, the outer cover shrinkable region 35 is formed. In other words, when the outer cover 3, or in other words, the stretchable portion that is present in each of the front portion 1A and the rear portion 1C shrinks in the lateral direction Y, as shown in Fig. 6, other diaper constituent members (the back sheet 22, the absorbent member 23, the top sheet 21, and the extension portion 3 IE of the outer layer sheet 31) that are integrally formed directly or indirectly with the outer cover 3 also shrink in the lateral direction Y. Fig. 7 schematically shows a state in which the extension portion 3 IE of the outer layer sheet 31 has shrunk in the lateral direction Y. The shrunk state of the extension portion 3 IE is substantially the same as the shrunk state of the outer cover 3, and as shown in Fig. 7, an uneven structure that is similar to the uneven structure (see Fig. 8) of the outer cover 3 that has shrunk in the lateral direction Y is formed in the extension portion 3 IE.

[0026]

Fig. 8 shows a portion of the outer cover shrinkable region 35 of the diaper 1 when it is in its natural state or worn state. As shown in Figs. 6 and 8, in the present embodiment, in the outer cover shrinkable region 35, the uneven structure in which ridge portions 36 and groove portions 37 that extend in the longitudinal direction X are alternately provided in the lateral direction Y is formed not only on the skin-facing surface, or in other words, the surface where the absorbent assembly 2 is disposed, but also on the non-skin-facing surface. The ridge portions 36 on the skin-facing surface side and the ridge portions 36 on the non-skin-facing surface side are at the same positions in the lateral direction Y, and the groove portions 37 on the skin-facing surface side and the groove portions 37 on the non-skin-facing surface side are also at the same positions in the lateral direction Y.

[0027]

In the present embodiment, in the outer cover 3 that is provided at least in the front portion 1A and the rear portion 1C, as shown in Figs. 8 and 9, the outer layer sheet 31 and the inner layer sheet 32 are bonded to each other at a plurality of outer cover bonding portions 38 that are intermittently provided in both the longitudinal direction X and the lateral direction Y, and the below-waist elastic members 5 are provided so as to not pass through the outer cover bonding portions 38. The plurality of below-waist elastic members 5 are bonded to the both sheets 31 and 32 only at both end portions of the below-waist elastic members 5 in their length direction, specifically, the side seal portions S or portions in the vicinity thereof, and are not bonded to the both sheets 31 and 32 at other portions. In the outer cover 3 configured as described above, each of the outer layer sheet 31 and the inner layer sheet 32 forms a plurality of folds that span across the plurality of below-waist elastic members 5, and extend continuously in the longitudinal direction X when the diaper 1 is in its natural state or worn state. The folds function as the ridge portions 36 in the outer cover shrinkable region 35, and the spaces between the folds function as the groove portions 37 in the outer cover shrinkable region 35. As the outer cover that has folds as described above, it is possible to use, for example, a composite stretchable member disclosed in JP 2009-118986 A that is an earlier application filed by the applicant of the present application.

[0028]

The present embodiment is configured such that the outer cover shrinkable region 35 is more reliably formed in the region where each longitudinal end portion 230 of the absorbent member 23 is disposed, and the vicinity thereof, in particular, in each longitudinal end of the absorbent member 23, and the vicinity thereof (each longitudinal end 2X of the absorbent assembly 2, and the vicinity thereof).

That is, as shown in Fig. 4, the top sheet 21 has an extension portion 2IE that extends outward from the longitudinal end portion of the absorbent core 24 in the longitudinal direction X. As viewed in a plan view shown in Fig. 2, the extension portion 2IE overlaps the below-waist elastic members 5. More specifically, in the present embodiment, as shown in Fig. 4, not only the top sheet 21, but also the back sheet 22 and the core wrap sheet 25 each have an extension portion that extends outward from the longitudinal end portion of the absorbent core 24 in the longitudinal direction X. The ends in the extension direction of the extension portions of the sheets 21, 22, and 25 are at the same position in the longitudinal direction X, and together form the longitudinal end 2X of the absorbent assembly 2. Also, the longitudinal end of the absorbent member 23 is a longitudinal end of the core wrap sheet 25 that is located on the outermost side in the longitudinal direction X among the constituent members of the absorbent member 23, and is flush with the longitudinal end 2X of the absorbent assembly 2. That is, in the longitudinal end of the absorbent member 23 and the vicinity thereof (the longitudinal end 2X of the absorbent assembly 2 and the vicinity thereof), there is a region where the absorbent core 24 that is highly rigid is not provided, and the below-waist elastic members 5 cross the absorbent core-absent region in the lateral direction Y. With this configuration, when the below-waist elastic members 5 shrink in the lateral direction Y when the diaper 1 is in its natural state or worn state, the longitudinal end of the absorbent member 23 and the vicinity thereof shrink in the same direction more easily, and thus an outer cover shrinkable region 35 that has an uneven structure with a clear height difference between the ridge portions 36 and the groove portions 37 is likely to be formed in the region where the longitudinal end portion 230 of the absorbent member 23 is disposed, and the vicinity thereof. The formation of the outer cover shrinkable region 35 that has an uneven structure with a clear height difference can contribute to further improvement of the air permeability of the diaper 1, in conjunction with an uneven structure composed of projections 210 and depressions 211 formed on the skin-facing surface of the top sheet 21, which will be described later.

[0029]

As shown in Figs. 4 and 7, the outer layer sheet 31 and the inner layer sheet 32 in the outer cover shrinkable region 35 include through holes 33 extending through the both sheets 31 and 32 in the thickness direction in the groove portions 37 that are present on the outer side in the longitudinal direction X of the longitudinal end portion 230 of the absorbent member 23 (the longitudinal end 2X of the absorbent assembly 2). In the present embodiment, as shown in Fig. 7, in each groove portion 37, a plurality of through holes 33 are intermittently provided at a predetermined spacing in the longitudinal direction X. However, the both sheets 31 and 32 do not include through holes 33 in the ridge portions 36 in the outer cover shrinkable region 35.

[0030]

The through holes 33 function as discharge pores for discharging water vapor derived from a waste liquid such as urine that can cause a build-up of moisture when the diaper 1 is worn. Considering the vapor discharge function of the through holes 33, in the case where both the outer layer sheet 31 and the inner layer sheet 32 have a plurality of through holes 33, it is preferable that at least some of the through holes 33 of the outer layer sheet 31 and the inner layer sheet 32 overlap with each other, and it is more preferable that all of the through holes 33 of the outer layer sheet 31 and the inner layer sheet 32 overlap in one-to-one correspondence with each other. There is no particular limitation on the shape of each through hole 33 as viewed in a plan view, and any shape can be selected as appropriate such as a circular shape, a triangular shape, or other polygonal shape. Also, the dimensions and the shape of each through hole 33 as viewed in a plan view may be the same between the outer layer sheet 31 and the inner layer sheet 32, or may be different. With respect to the degree of overlap between the through holes 33 of the outer layer sheet 31 and the through holes 33 of the inner layer sheet 32 in the case where the through holes 33 of the outer layer sheet 31 and the through holes 33 of the inner layer sheet 32 have the same dimensions and shape as viewed in a plan view, they do not necessarily overlap completely with each other, and may partially overlap with each other.

[0031]

In the present embodiment, as shown in Fig. 4, the through holes 33 extend through the outer cover bonding portions 38 at which the outer layer sheet 31 and the inner layer sheet 32 are bonded, in the thickness direction. That is, in the present embodiment, it can be said that each of the outer layer sheet 31 and the inner layer sheet 32 includes a plurality of through holes 33, and each of the through holes 33 of the outer layer sheet 31 overlaps a corresponding one of the through holes 33 of the inner layer sheet 32 at a position of a corresponding one of the outer cover bonding portions 38. With this configuration, the shape retainability of the through holes 33 is improved, and the vapor in the diaper 1 can be more reliably discharged to the outside via the through holes 33, and it is therefore possible to effectively prevent a build-up of moisture.

[0032]

In the present embodiment, a through hole indicated by reference numeral 33’ in

Fig. 4 is located between a below-waist elastic member 5’ and the longitudinal end portion 230 of the absorbent member as shown in the diagram, the below-waist elastic member 5’ being one of the plurality of below-waist elastic members 5 that is not overlapped by the longitudinal end portion 230 of the absorbent member 23 and is closest to the longitudinal end portion 230 of the absorbent member 23 (the longitudinal end 2X of the absorbent assembly 2) as viewed in a plan view. Because the through hole 33’ is provided at the above-described specific position, the through hole 33’ has particularly excellent shape retainability as compared with the other through holes 33 that are provided at positions farther from the absorbent member 23 than the through hole 33’. Accordingly, the through hole 33’ can stably perform its vapor discharging function while the diaper 1 is worn. That is, in the outer cover shrinkable region 35 where the through holes 33 are provided, when the outer cover 3 (the front extension portion 3 IE) comes into close contact with the skin due to shrinkage of the below-waist elastic members 5 when the diaper 1 is worn, the through holes 33 formed in that contact area may be closed due to deformation of the outer cover 3, inhibiting air permeation. However, the through hole 33’ is provided at a position closer to the absorbent member 23 than to the contact area, and it is therefore less likely to be affected by the absorbent member 23 that is highly rigid and unlikely to deform and be closed, and thus air permeation is unlikely to be inhibited. For this reason, the buil-up of moisture preventing effect described above can be further improved. In the embodiment shown in the diagram, only one through holes 33’ is shown, but a plurality of through holes 33’ may be formed. The through holes 33’ have the same configuration as the through holes 33 except for the position at which the through holes 33’ are provided.

[0033]

From the viewpoint of more reliably causing the through holes 33 to exhibit their function and effect, it is preferable to set the dimensions and the like thereof as follows.

The maximum length of each through hole 33 as viewed in a plan view (or the diameter in the case where the through hole 33 has a circular shape as viewed in a plan view) is preferably 1 mm or more, more preferably 1.5 mm or more, and preferably 5 mm or less, and more preferably 4 mm or less.

The number of through holes 33 per unit area in the outer cover shrinkable region 35 is preferably 1 or more, more preferably 2 or more, and preferably 15 or less, and more preferably 12 or less based on the area of a 10 mm square-shaped region as viewed in a plan view.

[0034]

As described above, in the outer cover 3, the portions (the stretchable portions) that are respectively located in the front portion 1A and the rear portion 1C shrink in the lateral direction Y when the diaper 1 is in its natural state or worn state, and thus outer cover shrinkable regions 35 that have an uneven structure that is composed of the ridge portions 36 and the groove portions 37 are formed on the skin-facing surface side. The top sheet 21 also has an uneven structure that corresponds to the uneven structure on its skin-facing surface.

[0035]

That is, as shown in Figs. 6 and 7, on the skin-facing surface of the top sheet 21, a plurality of projections 210 that protrude toward the skin of the wearer, and a plurality of depressions 211 that are each located between projections 210 and 210 that are adjacent in the lateral direction Y and extend in the longitudinal direction X are formed. In the top sheet 21 of the present embodiment, the projections 210 that extend in the longitudinal direction X and the depressions 211 that extend in the longitudinal direction X are alternately provided in the lateral direction Y, and an uneven structure is thereby formed in the skin-facing surface of the top sheet 21. The projections 210 and the depressions 211 are continuous over the entire length in the longitudinal direction X of the top sheet 21. The top sheet 21 may have an uneven structure as described above at least in the skin-facing surface. The non-skin-facing surface of the top sheet 21 may have an uneven structure as in the present embodiment, but may not have an uneven structure.

[0036] the uneven structure composed of the projections 210 and the depressions 211 in the top sheet 21, when the diaper 1 is in its flat-out and uncontracted state, or in other words, when the below-waist elastic members 5 of the outer cover 3 are stretched out in the lateral direction Y, as shown in Fig. 5, sub-projections 210’ and sub-depressions 211’ are alternately provided in the lateral direction Y, and thus the top sheet 21 as a whole has a corrugated shape that has regularly arranged projections and depressions. However, when the diaper 1 is in its natural state or worn state, or in other words, when the below-waist elastic members 5 shrink in the lateral direction Y, as shown in Fig. 6, the sub-projections 210’ and the sub-depressions 211’ shrink in the lateral direction Y together with other constituent members that are integrally formed with the outer cover 3, as a result of which, one or more sub-projections 210’ and one or more sub-depressions 21Γ are combined to form one projection 210, and a portion of the plurality of sub-depressions 211’ forms a depression 211 that protrudes in the opposite direction to the protruding direction of the projections 210 (toward the absorbent member 23). That is, each projection 210 of the top sheet 21 when the diaper 1 in its natural state or worn state is an aggregate of sub-projections 210’ and sub-depressions 21Γ, and on the outer surface (skin-facing surface) of the projection 210, relatively fine projections and depressions that are composed of the sub-projections 210’ and the sub-depressions 211’ are formed. Accordingly, the projections 210 do not come into full contact with a hydrophobic sheet 3 IE (described later) that covers the outer surface of the projections 210, and thus void portions are formed between the projections 210 and the hydrophobic sheet 3 IE. The sub-depressions 21Γ and the depressions 211 normally have mutually different shapes and/or dimensions, but may have substantially the same shapes and/or dimensions.

[0037]

Also, in the diaper 1 according to the present embodiment, as shown Fig. 7, at least some of the plurality of depressions 211 of the top sheet 21 are at the same positions in the lateral direction Y as the groove portions 37 in the outer cover shrinkable region 35. That is, the groove portions 37 in the outer cover shrinkable region 35 are present on extension lines in the longitudinal direction X of at least some of the plurality of depressions 211 of the top sheet 21. In the embodiment shown in Fig. 7, the plurality of depressions 211 in the skin-facing surface of the top sheet 21 corresponds in one-to-one with each of the plurality of groove portions 37 in the outer cover shrinkable region 35. That is, each depression 211 is provided at the same position in the lateral direction Y as a corresponding one of the groove portions 37. With this configuration, the air permeability of the diaper 1 is improved, and thus a build-up of moisture is unlikely to occur in the diaper 1 when it is worn. As a result, the occurrence of skin issues such as itchiness and a rash is effectively prevented.

[0038]

That is, in the diaper 1, because the groove portions 37 of the outer cover 3 (the outer cover shrinkable region 35) in a shrunk state are provided at the same positions in the lateral direction Y as the depressions 211 of the top sheet 21, air flow paths that extend in the longitudinal direction X, which are composed of the depressions 211 and the groove portions 37 that are provided at the same positions in the lateral direction Y, are formed so as to extend from the absorbent assembly 2 to the longitudinal end 3X (i.e., the opening edge of the waist opening WH) of the outer cover 3. As a result, air permeability is increased, and thus a build-up of moisture is unlikely to occur in the diaper 1 when it is worn. That is, even if waste liquids such as urine and sweat absorbed and retained in the absorbent member 23 (the absorbent core 24) of the absorbent assembly 2 evaporate due to the body temperature of the wearer, and are discharged from the top sheet 21 toward the skin of the wearer as water vapor while the diaper 1 is worn, the water vapor passes through the depressions 211 and the groove portions 37, and is discharged to the outside of the diaper 1 through the waist opening WH, or is discharged to the outside of the diaper 1 through the through holes 33 formed in the groove portions

37. Accordingly, a build-up of moisture is unlikely to occur in the diaper 1 while it is worn, and thus the wearer is unlikely to have skin issues. Normally, the interval (projection/depression pitch) between projections 210 and depressions 211 of the top sheet 21 is smaller than the interval (ridge/groove pitch) between ridge portions 36 and groove portions 37 of the outer cover 3. Accordingly, the groove portions 37 that have a relatively large length in the lateral direction Y, or in other words, a relatively large width are always located at the same positions in the lateral direction Y as the depressions 211 that have a relatively small length in the lateral direction Y, or in other words, a relatively small width, but not necessarily vice versa. At least a portion of the plurality of depressions 211 is located at the same positions in the lateral direction Y as the groove portions 37. Specifically, it is preferable that one out of three depressions 211 is located at the same position as one groove portion 37.

[0039]

As used herein, the expression a depression 211 of the top sheet 21 is located at the same position in the lateral direction Y as a groove portion 37 in the outer cover shrinkable region 35 (the outer cover 3) means that an imaginary center line that divides the groove portion 37 into halves in the lateral direction Y and extends in the longitudinal direction X passes through a region within 1 mm in the lateral direction Y from a reference line that is an imaginary center line that divides the depression 211 into halves in the lateral direction Y and extends in the longitudinal direction X.

[0040]

Also, in the diaper 1, as viewed in a plan view, the below-waist elastic members 5 pass through an overlapping portion that overlaps with the longitudinal end portion 230 of the absorbent member 23, and cross the overlapping portion in the lateral direction Y. Accordingly, when the outer cover 3 (the outer cover shrinkable region 35) shrinks in the lateral direction Y when the diaper 1 is worn, the absorbent member 23, or in other words, the absorbent assembly 2 is unlikely to be separated upward from the outer cover 3. This also improves air permeability, and prevents a build-up of moisture and liquid leakage.

[0041]

Also, even if the absorbent assembly 2 shrinks in the lateral direction Y and comes into contact with the skin of the wearer when the diaper 1 is worn, or even if the absorbent assembly 2 is separated upward from the outer cover 3 and comes into contact with the skin of the wearer when the diaper 1 is worn, because the skin-facing surface of the top sheet 21 that is the contact surface with the skin has an uneven structure composed of the projections 210 and the depressions 211, the skin-facing surface of the top sheet 21 as a whole does not come into full contact with the skin of the wearer. This also improves air permeability and prevents a build-up of moisture. If the skin-facing surface of the top sheet is a flat surface without an uneven structure, the flat surface as a whole may come into full contact with the skin of the wearer, and thus it may not be able to prevent a build-up of moisture.

[0042]

From the viewpoint of more reliably causing the diaper 1 as described above to exhibit its function and effect, it is preferable to set the dimensions and the like of the constituent elements as follows.

In the skin-facing surface of the top sheet 21, the separation distance between each peaks (the portions of projections that protrude farthest toward the skin of the wearer) of projections 210 and 210 that are adjacent in the lateral direction Y is preferably 1.5 mm or more, and more preferably 2 mm or more, and preferably 5 mm or less, and more preferably 4.5 mm or less. The separation distance between the peaks of projections 210 in the lateral direction Y is closely related to the length in the lateral direction Y, or in other words, the width of the depressions 211.

The length in the longitudinal direction X of the depressions 211 is preferably 7 mm or more, and more preferably 10 mm or more, and preferably 60 mm or less, and more preferably 50 mm or less.

When the diaper 1 is in its natural state or worn state, the number of depressions 211 of the top sheet 21 at the position of the longitudinal end 2X of the absorbent assembly 2 is preferably 15 or more, and more preferably 20 or more, and preferably 50 or less, and more preferably 40 or less.

[0043]

The number of below-waist elastic members 5 in the front portion 1A or the rear portion 1C is preferably 10 or more, and more preferably 12 or more, and preferably 35 or less, and more preferably 30 or less.

In the front portion 1A or the rear portion 1C, as viewed in a plan view, the number of below-waist elastic members 5 that pass through the overlapping portion that overlaps the absorbent member 23, and cross the absorbent member 23 in the lateral direction Y is preferably 1 or more, and preferably is 15 or less, and more preferably is 12 or less.

[0044]

In the diaper 1 according to the present embodiment, as shown in Figs. 2, 4, and 5, the top sheet 21 overlaps the longitudinal end portions 230 of the absorbent member 23 in the outer cover shrinkable regions 35 (the absorbent assembly-absent region 10 and the absorbent assembly-present region 11), and in each outer cover shrinkable region 35, the skin-facing surface of the top sheet 21 is covered with a hydrophobic sheet 3 IE as viewed in a plan view. The hydrophobic sheet 3 IE of the present invention is, as described above, the extension portion 3 IE that is a portion of the outer layer sheet 31.

[0045]

The hydrophobic sheet 3 IE is used primarily from the viewpoint of improving air permeability, and can eliminate disadvantages caused by the uneven structure of the skin-facing surface of the top sheet 21. That is, in terms of air permeability, it is effective to form depressions 211 that extend in the longitudinal direction X in the skin-facing surface of the top sheet 21, but the depressions 211 may function not only as transport paths for water vapor, but also as transport paths for waste liquids such as urine. Accordingly, there is a possibility that waste liquids will leak to the outside via the depressions 211, causing a liquid leakage. In contrast, as shown in Figs. 2, 4, and 5, the uneven-structured skin-facing surface of the top sheet 21 is covered by the hydrophobic sheet 3 IE. Accordingly, waste liquids that can flow in the longitudinal direction X via the depressions 211 can be blocked by the hydrophobic sheet 3 IE, and thus a liquid leakage can be effectively prevented.

[0046]

The hydrophobic sheet 3 IE is preferably bonded to the top sheet 21 at the projections 210, more preferably at the peaks of the projections 210 by bonding portions 6, and is not bonded to the top sheet 21 at the depressions 211. With this configuration, even when the skin-facing surface of the top sheet 21 is covered with the hydrophobic sheet 3 IE, voids are formed between the depressions 211 and the hydrophobic sheet 3 IE at the positions of the depressions 211 in the skin-facing surface of the top sheet 21. Accordingly, there is no possibility that the function of the depressions 211 as air flow paths will be hindered. The bonding between the hydrophobic sheet 3 IE and the top sheet 21 can be implemented by using a known bonding means such as a hot melt adhesive. In the present embodiment, the bonding portions 6 are adhesive application portions.

[0047]

In the present embodiment, as shown in Fig. 4, the bonding portions 6 between the hydrophobic sheet 3 IE and the top sheet 21 are intermittently provided in the longitudinal direction X. More specifically, Fig. 5 shows a linear bonding portion 6 that is continuous over the entire length in the lateral direction Y of an overlapping portion between the hydrophobic sheet 3 IE and the top sheet 21, and extends linearly in the lateral direction Y as viewed in a plan view. A plurality of (three in Fig. 4) such linear bonding portions 6 are formed at a predetermined spacing in the longitudinal direction X. The bonding portions 6 themselves are capable of performing the effect of blocking waste liquids such as urine. By providing the bonding portions 6 that have such a function in the manner described above, in conjunction with the effect of preventing liquid leakage exhibited by the hydrophobic sheet 3 IE, it is possible to more effectively prevent liquid leakage.

[0048]

Also, in the present embodiment, as shown in Fig. 4, an inner-side end portion 31 EX of the hydrophobic sheet 3 IE in the longitudinal direction X is a free end portion that is not bonded to the top sheet 21. With this configuration, the inner-side end portion 31 EX of the hydrophobic sheet 3 IE in the longitudinal direction X rises upward toward the skin, and the effect of blocking waste liquids such as urine can be easily obtained.

[0049]

In the present invention, whether a sheet or a partial region of the sheet is hydrophilic or hydrophobic is determined based on the contact angle of fibers measured by the method described below. Specifically, fibers are determined as being hydrophilic when they have a contact angle of less than 90 degrees, and determined as being hydrophobic when they have a contact angle of 90 degrees or more. The smaller the contact angle of fibers measured by the method described below, the higher the hydrophilicity (the lower the hydrophobicity), and the greater the contact angle, the lower the hydrophilicity (the higher the hydrophobicity). In the hydrophobic sheet 3 IE according to the present embodiment, the fibers in the entire region thereof have a contact angle measured by the method described below of 90 degrees or more.

[0050] <Method for Measuring Contact Angle>

A measurement target sheet (non-woven fabric) is set with its cross section in the thickness direction facing upward. A plurality of fibers are randomly sampled from a segment from the top surface of the sheet in the thickness direction to 1/10 of the thickness, and the water contact angle is measured. As the measurement apparatus, an auto contact angle meter MCA-J available from Kyowa Interface Science Co., Ltd. is used. For contact angle measurement, distilled water is used. The amount of liquid discharged from an inkjet-type water droplet injector (Pulse Injector CTC-25 available from Cluster Technology, Co., Ltd., with an injector pore size of 25 pm) is set to 15 picoliters. A water droplet is dropped directly onto the center of each fiber, during which the droplet is recorded by a horizontally installed high-speed video recorder that is connected to a camera. The video recorder is preferably a personal computer equipped with a high-speed capture apparatus, from the view point of performing image analysis later. In this measurement, an image is recorded every 17 milliseconds. In the recorded video, the first image of a water droplet first dropped onto the fiber is subjected to image analysis, using accompanying software FAMAS (version 2.6.2, measurement method: droplet method, analysis method: Θ/2 method, image processing algorithm: no reflection, image processing image mode: frame, threshold level: 200, curvature correction: no). Then, the angle between the fiber and the surface of the water droplet that is in contact with the air is calculated, and the calculated value is defined as the contact angle. As the fiber, a fiber that has been cut to a fiber length of about 1 mm is used, and the fiber is placed on the sample stage of the contact angle meter, and held horizontally. A value obtained by measuring the contact angles of five fibers with accuracy to the first decimal place, and averaging the measured angles obtained at ten locations in total (which is rounded to first decimal place) is defined as a contact angle. A fiber with a lower contact angle has higher hydrophilicity. The measurement environment is set to a room temperature of 22±2°C and humidity of 65 ± 2%RH.

[0051]

The hydrophobic sheet 3 IE according to the present embodiment is a portion of the outer layer sheet 31, but the hydrophobic sheet according to the present invention is not limited thereto. The hydrophobic sheet may be a hydrophobic sheet provided separate from the other constituent members of the diaper 1. As the hydrophobic sheet according to the present invention, a non-woven fabric that is stretchable in the lateral direction Y is preferably used. By using a hydrophobic sheet 3 IE made of such a stretchable sheet, the hydrophobic sheet 3 IE is bonded to the top sheet 21 at the peaks of projections 210 with the bonding portions 6, but is not bonded to the top sheet 21 at depressions 211, and thus voids are likely to be formed between the hydrophobic sheet 3 IE and the top sheet 21 at the positions of the depressions 211 on the skin-facing surface of the top sheet 21. Accordingly, it is possible to obtain the effect in that function of air flow paths exhibited by the depressions 211 is unlikely to be hindered.

[0052]

In this specification, the term stretchable sheet refers to a sheet that is stretchable in a predetermined direction (for example, the lateral direction), and more specifically, a sheet that has a maximum elongation in a predetermined direction (for example, the lateral direction) of 100% or more, and an elongation recovery rate (elongation recovery rate at an elongation of 100%) of at least 70% or more, the elongation recovery rate being obtained by stretching the sheet in the predetermined direction at an elongation of 100%, and then allowing the sheet to shrink.

[0053]

The hydrophobic sheet 3 IE that is stretchable in the lateral direction Y is configured so as to be capable of stretching more in the lateral direction Y than in the longitudinal direction X. More specifically, the outer layer sheet 31 stretches out significantly in the lateral direction Y, and thereafter shrinks (at a maximum elongation of 100% or more, and an elongation recovery rate 70% or more), but stretches out only slightly in the longitudinal direction X (for example, at a maximum elongation of 50% or less). The elongation recovery rate of the sheet is measured using the following method.

[0054] <Method for Measuring Elongation Recovery Rate>

A sample piece having a length of 50 mm and a width of 25 mm is prepared from a measurement target sheet. The sample piece is fixed between chucks (chuck-to-chuck distance K0) in a tensile testing machine (TENSILON RTC-1150A available from Orientec, Co., Ltd.). By increasing the distance between chucks at a traction speed of 300 mm/min, the sample piece is pulled and stretched out to a length K2 (= K0 x 2) that is the length of the sample piece at an elongation of 100%, and then the distance between chucks is decreased at the same speed as the traction speed. The length of the sample piece when the tensile stress reaches 0 is defined as length Kl after elongation recovery. The elongation recovery rate of the measurement target sheet at an elongation of 100% is calculated by the following equation:

elongation recovery rate (%) at an elongation of 100% = [(K2 - Kl) / (K2 - KO)] x 100.

[0055]

Preferred examples of the stretchable hydrophobic sheet 3 IE include: (1) a stretchable sheet in which a stretchable fiber layer is integrally formed on both sides or one side of an elastic fiber layer; (2) a stretchable sheet in which a stretchable fiber layer is integrally formed on both sides or one side of a net-like elastic sheet; (3) a stretchable sheet in which a fiber layer that is stretchable is integrally formed on both sides or one side of an elastic sheet made of an elastic film; and (4) a stretchable sheet in which a large number of elastic filaments arranged to extend in one direction without crossing each other are bonded over the entire length of a stretchable non-woven fabric substantially in a non-stretched-out state. As the method for integrally forming an elastic fiber layer and a stretchable fiber layer, it is possible to use, for example, methods such as stacking and hydroentangling the elastic fiber layer and the stretchable fiber layer, entangling the fibers using an air-through method, and bonding the elastic fiber layer and the stretchable fiber layer using heat embossing, an adhesive, or ultrasonic bonding.

[0056]

Fig. 10 shows a preferred example of the stretchable hydrophobic sheet 3 IE. The hydrophobic sheet 3 IE shown in Fig. 10 corresponds to the stretchable sheet (4) described above, and is configured such that elastic filaments in the form of threads are bonded to one surface of a stretchable fiber layer composed mainly of a non-elastic fiber. The hydrophobic sheet 3 IE includes both fiber sheets 310 and 311 that serve as the fiber layers, and elastic members 312 that are provided between the both sheets 310 and 311, and serve as elastic fdaments. The stretchable hydrophobic sheet 3 IE that has the above-described configuration can be produced using, for example, the method disclosed in JP 2009-61743 A.

[0057]

Both of the both sheets 310 and 311 that constitute the stretchable hydrophobic sheet 3 IE are stretchable. The sheets 310 and 311 are stretchable in the same direction as the direction in which the elastic members 312 stretch (the lateral direction Y). As used herein, the term stretchable encompasses the following cases: (i) the constituent fiber of the sheets 310 and 311 is stretchable; and (ii) the constituent fiber is not stretchable, but the sheets 310 and 311 as a whole are stretchable as a result of the fibers that are bonded at intersections being separated from each other, or a three-dimensional structure formed by a plurality of bonded fibers or the like being structurally changed, or the constituent fiber being torn.

[0058]

The elastic members 312 that constitute the stretchable hydrophobic sheet 3 IE are elastic filaments formed by drawing a melted or softened elastic resin. Each of the plurality of elastic members 312 is substantially continuous over the entire length of the sheet 3 IE (the entire length in the lateral direction Y of the outer cover 3). The plurality of elastic members 312 are arranged so as to extend in one direction (the lateral direction Y) without crossing each other. The elastic members 312 are bonded, in a substantially non-stretched-out state, to the both sheets 310 and 311. The bonding of the elastic members 312 between the sheets 310 and 311 in sheet 3 IE is implemented by constituent fibers (non-elastic fibers) that constitute the sheets 310 and 311 being embedded in the elastic members 312 and fused to the elastic members 312, and thus is not implemented by using an adhesive such as a hot melt adhesive. Accordingly, no adhesive is present between the sheets 310 and 311 (stretchable fiber layers composed mainly of non-elastic fibers) and the elastic members 312 that are bonded to the sheets 310 and 311.

[0059]

The stretchable hydrophobic sheet 3 IE is configured to be capable of stretching in the same direction as the direction (the lateral direction Y) in which the elastic members 312 stretch. The stretchability of the sheet 3 IE is provided by the elasticity of the elastic members 312. When the sheet 3 IE is pulled in the same direction as the direction in which the elastic members 312 stretch, the elastic members 312 and the sheets 310 and 311 stretch out. When the pulling of the sheet 3 IE is stopped, the elastic members 312 shrink, and as a result of the shrinkage, the sheets 310 and 311 return to their original state before the sheet 3 IE was pulled. Also, in the sheet 3 IE, there is no other elastic member bonded perpendicular to the elastic members 312. Accordingly, when the sheet 3 IE is pulled in the same direction as the direction (the lateral direction Y) in which the elastic members 312 stretch, the sheet 3 IE stretches out with almost no shrinkage of the sheet 3 IE in the lateral direction Y, or in other words, so-called width shrinkage.

[0060]

The both sheets 310 and 311 that constitute the stretchable hydrophobic sheet 3 IE may be non-woven fabrics made using a staple fiber. Examples of the non-woven fabrics include air-through non-woven fabrics, heat roll non-woven fabrics, spunlace non-woven fabrics, spunbond non-woven fabrics, and melt blown non-woven fabrics. The sheet 310 and the sheet 311 may be the same type of sheets, or may be different types of sheets. As used herein, the expression the same type of sheets refers to sheets that are the same in terms of the sheet manufacturing process, the type of constituent fiber of the sheet, the fiber diameter and the length of the constituent fiber, and the thickness and the basis weight of the sheet. Sheets that are different in terms of at least one of these are different types of sheets.

[0061]

The elastic members 312 (elastic filaments) that are included in the stretchable hydrophobic sheet 3 IE are made using, for example, a thermoplastic elastomer, rubber, or the like as the raw material. In particular, if a thermoplastic elastomer is used as the raw material, it is possible to perform melt spinning using an extruder as with an ordinary thermoplastic resin. Also, elastic filaments obtained through melt spinning can be thermally fused with ease, and thus they are preferably used to form the sheet 3 IE. Examples of the thermoplastic elastomer include: styrene-based elastomers such as SBS (styrene-butadiene-styrene), SIS (styrene-isoprene-styrene), SEBS (styrene-ethylene-butadiene-styrene), and SEPS (styrene-ethylene-propylene-styrene); olefin-based elastomers (an ethylene-based α-olefm elastomer, and a propylene-based elastomer obtained by copolymerizing ethylene, butane, octene, and the like); polyester-based elastomers, and polyurethane-based elastomers. These may be used alone or in a combination of two or more. Also, it is also possible to use a core-sheath or side-by-side composite fiber made of any of the resins listed above.

[0062]

On the other hand, the outer layer sheet 31 and the inner layer sheet 32 that constitute the outer cover 3 are, as described above, non-stretchable sheets that are not stretchable. In this specification, the term non-stretchable sheet refers to a sheet that has an elongation recovery rate measured according to <Method for Measuring Elongation Recovery Rate> described above of 20% or less, or a sheet that tears before the sheet is stretched to an elongation of 100%.

[0063]

As the outer layer sheet 31 and the inner layer sheet 32 that are non-stretchable, non-woven fabrics made using various manufacturing methods can be preferably used. Examples include spunbond non-woven fabrics, air-through non-woven fabrics, and needle punched non-woven fabrics. The constituent fiber of the non-woven fabrics that can be used as the non-stretchable sheets 31 and 32 may be, for example, a fiber made of a polyester such as polyethylene (PE), polypropylene (PP), polyethylene terephthalate (PET) or polybutylene terephthalate (PBT), or a polyamide. The fiber that constitutes the non-woven fabrics that can be used as the non-stretchable sheets 31 and 32 may be a staple fiber or a long fiber, and may be hydrophilic or hydrophobic. It is also possible to use a core-sheath or side-by-side composite fiber, a split fiber, a modified cross-section fiber, a crimped fiber, a thermal shrinkage fiber, or the like. These fibers may be used alone or in a combination of two or more.

[0064]

Up to here, the present invention has been described by way of a preferred embodiment of the present invention, but the present invention is not limited to the embodiment described above.

For example, in the embodiment given above, the projections 210 and the depressions 211 that constitute the uneven structure of the skin-facing surface of the top sheet 21 are provided continuously over the entire length in the longitudinal direction X of the top sheet 21 to form a ridge/groove structure. However, the projections 210 and the depressions 211 do not necessarily from such a ridge/groove structure, and in short, it is only necessary that a plurality of depressions 211 that extend in the longitudinal direction X are located between projections 210 and 210 that are adjacent in the lateral direction Y.

Also, in the embodiment given above, the top sheet 21 is provided to overlap the longitudinal end portions 230 of the absorbent member 23 that are present in the outer cover shrinkable regions 35 as viewed in a plan view, and in each outer cover shrinkable region 35, the skin-facing surface of the top sheet 21 is covered by the hydrophobic sheet 3 IE, but such a configuration is not a requirement in the present invention. However, as described above, with this configuration, in particular, as a result of the skin-facing surface having an uneven structure of the top sheet 21 being covered by the hydrophobic sheet 3 IE, the issue of leakage of waste liquids such as urine to the outside through the depressions 211 that form the uneven structure is more effectively prevented.

Also, in the embodiment given above, the outer layer sheet 31 is a single continuous sheet as is the inner layer sheet 32, but may be a combination of a plurality of sheets.

Also, the outer cover 3 may be divided into an outer cover front region located in the front portion, and an outer cover rear region located in the rear portion, and the absorbent assembly 2 may be fixedly provided to span across the outer cover front region and the outer cover rear region.

With respect to the above-described embodiment of the present invention, the following additional statements will be further disclosed.

[0065] < 1 > A pull-on disposable diaper comprising:

a front portion that is to be placed on an abdominal side of a wearer, a rear portion that is to be placed on a dorsal side of the wearer, and a crotch portion that is provided between the front portion and the rear portion, the pull-on disposable diaper having a longitudinal direction that extends from the front portion to the rear portion via the crotch portion, and a lateral direction that is perpendicular to the longitudinal direction, and the pull-on disposable diaper further including:

an absorbent assembly including an absorbent member and a top sheet that is provided on a skin-facing surface side of the absorbent member; and an outer cover that is provided on a non-skin-facing surface side of the absorbent assembly, and fixes the absorbent assembly, and both lateral side edge portions of the outer cover in the front portion and both lateral side edge portions of the outer cover in the rear portion being bonded to form a waist opening and a pair of leg openings, wherein the outer cover includes an outer layer sheet that is located on a side that is relatively far from the absorbent assembly and an inner layer sheet that is located on a side that is relatively close to the absorbent assembly, and further includes a stretchable portion in at least one of the front portion and the rear portion, the stretchable portion being stretchable in the lateral direction, a plurality of below-waist elastic members that are stretched out in the lateral direction are provided intermittently in the longitudinal direction between the outer layer sheet and the inner layer sheet in the stretchable portion, such that a portion of the plurality of below-waist elastic members pass through an overlapping portion that overlaps a longitudinal end portion of the absorbent member, and cross the longitudinal end portion in the lateral direction as viewed in a plan view, the stretchable portion shrinks in the lateral direction due to shrinkage of the below-waist elastic members in the stretchable portion so as to form an outer cover shrinkable region, and the outer cover shrinkable region has, on the skin-facing surface side, an uneven structure in which ridge portions and groove portions that extend in the longitudinal direction are alternately provided in the lateral direction, at least one of the outer layer sheet and the inner layer sheet in the outer cover shrinkable region includes through holes that extend therethrough in a thickness direction thereof in the groove portions that are present on an outer side in the longitudinal direction of the longitudinal end portion of the absorbent member, and on the skin-facing surface of the top sheet, a plurality of projections that protrude toward the skin of the wearer, and a plurality of depressions that are located between the projections that are adjacent in the lateral direction and extend in the longitudinal direction are formed such that at least some of the plurality of depressions are at the same positions in the lateral direction as the groove portions in the outer cover shrinkable region.

[0066] < 2 > The pull-on disposable diaper as set forth in clause < 1 >, wherein the top sheet overlaps the longitudinal end portion of the absorbent member that is present in the outer cover shrinkable region, as viewed in a plan view.

< 3 > The pull-on disposable diaper as set forth in clause < 1 > or < 2 >, wherein the absorbent member includes an absorbent core that contains an absorbent material, the top sheet includes a portion that extends outward in the longitudinal direction from a longitudinal end portion of the absorbent core, and the extension portion of the top sheet overlaps the below-waist elastic members as viewed in a plan view.

< 4 > The pull-on disposable diaper as set forth in any one of clauses < 1 > to < 3 >, wherein the through holes include a through hole that is present between the longitudinal end portion of the absorbent member and one of the plurality of below-waist elastic members that is not overlapped by the longitudinal end portion of the absorbent member and is closest to the longitudinal end portion of the absorbent member as viewed in a plan view.

< 5 > The pull-on disposable diaper as set forth in any one of clauses < 1 > to < 4 >, wherein both the outer layer sheet and the inner layer sheet include the plurality of through holes, and at least some of the through holes of the outer layer sheet and the inner layer sheet overlap with each other.

< 6 > The pull-on disposable diaper as set forth in any one of clauses < 1 > to < 5 >, wherein in the outer cover shrinkable region, the outer layer sheet and the inner layer sheet are bonded to each other at a plurality of outer cover bonding portions that are intermittently provided in both the longitudinal direction and the lateral direction, and the below-waist elastic members are provided so as to not pass through the outer cover bonding portions.

< 7 > The pull-on disposable diaper as set forth in clause < 5 > or < 6 >, wherein, in the outer cover shrinkable region, the outer layer sheet and the inner layer sheet are bonded to each other at a plurality of outer cover bonding portions that are intermittently provided in both the longitudinal direction and the lateral direction, and the through holes extend through the outer cover bonding portions in the thickness direction.

[0067] < 8 > The pull-on disposable diaper as set forth in any one of clauses < 1 > to < 7 >, wherein the outer layer sheet further includes, in addition to a portion that has the same shape and dimensions as those of the inner layer sheet, a front extension portion that extends outward from an end portion in the longitudinal direction on the front portion side of the inner layer sheet when the outer layer sheet and the inner layer sheet are stacked, and a rear extension portion that extends outward from an end portion in the longitudinal direction on the rear portion side of the inner layer sheet.

< 9 > The pull-on disposable diaper as set forth in clause < 8 >, wherein the front extension portion and the rear extension portion are each folded over the inner layer sheet so as to cover both longitudinal end portions of the absorbent assembly that is fixedly provided on the inner layer sheet, and are fixed.

< 10 > The pull-on disposable diaper as set forth in clause < 8 > or < 9 >, wherein, in the outer cover shrinkable region, the skin-facing surface of the top sheet is covered with a hydrophobic sheet, and the hydrophobic sheet serves as the front extension portion or the rear extension portion.

[0068] < 11 > The pull-on disposable diaper as set forth in any one of clauses < 1 > to < 9 >, wherein, in the outer cover shrinkable region, the skin-facing surface of the top sheet is covered with a hydrophobic sheet.

< 12 > The pull-on disposable diaper as set forth in clause < 10 > or < 11 >, wherein the hydrophobic sheet is bonded to the top sheet at the projections, but is not bonded to the top sheet at the depressions.

< 13 > The pull-on disposable diaper as set forth in clause < 12 >, wherein bonding portions at which the hydrophobic sheet and the top sheet are bonded are intermittently provided in the longitudinal direction.

< 14 > The pull-on disposable diaper as set forth in any one of clauses < 10 > to < 13 >, wherein an inner-side end portion of the hydrophobic sheet in the longitudinal direction is a free end portion that is not bonded to the top sheet.

< 15 > The pull-on disposable diaper as set forth in any one of clauses < 10 > to < 14 >, wherein the hydrophobic sheet is made of a non-woven fabric that is stretchable in the lateral direction.

< 16 > The pull-on disposable diaper as set forth in any one of clauses < 10 > to < 15 >, wherein the hydrophobic sheet is bonded to the top sheet at peaks of the projections, but is not bonded to the top sheet at the depressions.

[0069] < 17 > The pull-on disposable diaper as set forth in any one of clauses < 1 > to < 16 >, wherein each of the front portion and the rear portion is divided in the longitudinal direction into an absorbent assembly-absent region in which the absorbent assembly is not provided and an absorbent assembly-present region that is located on an inner side of the absorbent assembly-absent region in the longitudinal direction, and the below-waist elastic members are provided in both the absorbent assembly-absent region and the absorbent assembly-present region.

< 18 > The pull-on disposable diaper as set forth in clause < 17 >, wherein the outer cover shrinkable region is formed over an entire area of each of the absorbent assembly-absent region and the absorbent assembly-present region, and is also formed in an overlapping area of the absorbent assembly-present region that overlaps the absorbent assembly as viewed in a plan view.

[0070] < 19 >. The pull-on disposable diaper as set forth in any one of clauses < 1 > to < 18 >, wherein the outer cover shrinkable region has, on the non-skin-facing surface side, an uneven structure in which ridge portions and groove portions that extend in the longitudinal direction are alternately provided in the lateral direction.

< 20 > The pull-on disposable diaper as set forth in clause < 19 >, wherein, in the outer cover shrinkable region, the ridge portions on the skin-facing surface side and the ridge portions on the non-skin-facing surface side are located at the same positions in the lateral direction, and the groove portions on the skin-facing surface side and the groove portions on the non-skin-facing surface side are located at the same positions in the lateral direction.

< 21 > The pull-on disposable diaper as set forth in any one of clauses < 1 > to < 20 >, wherein the both lateral side edge portions of the outer cover in the front portion and the both lateral side edge portions of the outer cover in the rear portion are each bonded to form a pair of side seal portions, and the plurality of below-waist elastic members are bonded to both the outer layer sheet and the inner layer sheet only at the side seal portions or portions near the side seal portions, but are not bonded to the both sheets at other portions.

< 22 > The pull-on disposable diaper as set forth in any one of clauses < 1 > to < 21 >, wherein, when the diaper is in its natural state or worn state, each of the outer layer sheet and the inner layer sheet forms a plurality of folds that span across the plurality of below-waist elastic members, and extend continuously in the longitudinal direction, the folds function as the ridge portions, and spaces between the folds that are adjacent in the lateral direction function as the groove portions.

[0071] < 23 >. The pull-on disposable diaper as set forth in any one of clauses < 1 > to < 22 >, wherein, in each of the groove portions, the plurality of through holes are intermittently provided at a predetermined spacing in the longitudinal direction.

< 24 > The pull-on disposable diaper as set forth in any one of clauses < 1 > to < 23 >, wherein both of the outer layer sheet and the inner layer sheet include the plurality of through holes, and all of the through holes of the outer layer sheet and the inner layer sheet overlap in one-to-one correspondence with each other.

< 25 > The pull-on disposable diaper as set forth in any one of clauses < 1 > to < 24 >, wherein, in the outer cover shrinkable region, the outer layer sheet and the inner layer sheet are bonded to each other at a plurality of outer cover bonding portions that are intermittently provided in both of the longitudinal direction and the lateral direction, both the outer layer sheet and the inner layer sheet include the plurality of through holes, and one of the through holes of the outer layer sheet overlaps one of the through holes of the inner layer sheet at a position of one of the outer cover bonding portions.

< 26 > The pull-on disposable diaper as set forth in any one of clauses < 1 > to < 25 >, wherein the through holes each have a maximum length as viewed in a plan view of preferably 1 mm or greater, more preferably 1.5 mm or greater, and is preferably 5 mm or less, more preferably 4 mm or less.

< 27 > The pull-on disposable diaper as set forth in any one of clauses < 1 > to < 26 >, wherein the number of the through holes per unit area in the outer cover shrinkable region is preferably 1 or greater, more preferably 2 or greater, and is preferably 15 or less, more preferably 12 or less based on an area of a 10 mm square-shaped region as viewed in a plan view.

< 28 > The pull-on disposable diaper as set forth in any one of clauses < 1 > to < 27 >, wherein with regard to at least some of the plurality of depressions of the top sheet, the groove portions of the outer cover shrinkable region are present on extension lines of the depressions in the longitudinal direction.

< 29 > The pull-on disposable diaper as set forth in any one of clauses < 1 > to < 28 >, wherein each of the plurality of depressions in the skin-facing surface of the top sheet is in one-to-one correspondence with a corresponding one of the plurality of groove portions in the outer cover shrinkable region, and is at the same position in the lateral direction as the corresponding one of the groove portions.

[0072] < 30 > The pull-on disposable diaper as set forth in any one of clauses < 1 > to < 29 >, wherein, in the skin-facing surface of the top sheet, a separation distance between peaks of the projections that are adjacent in the lateral direction is preferably 1.5 mm or greater, more preferably 2 mm or greater, and is preferably 5 mm or less, more preferably 4.5 mm or less.

< 31 > The pull-on disposable diaper as set forth in any one of clauses < 1 > to < 30 >, wherein the depressions each have a length in the longitudinal direction of preferably 7 mm or greater, more preferably 10 mm or greater, and preferably 60 mm or less, more preferably 50 mm or less.

< 32 > The pull-on disposable diaper as set forth in any one of clauses < 1 > to < 31 >, wherein the number of the below-waist elastic members that are present in the front portion or the rear portion is preferably 10 or greater, more preferably 12 or greater, and is preferably 35 or less, more preferably 30 or less.

< 33 > The pull-on disposable diaper as set forth in any one of clauses < 1 > to < 32 >, wherein, in the front portion or the rear portion, the number of below-waist elastic members that pass through a portion that overlaps with the absorbent member, and cross the absorbent member in the lateral direction as viewed in a plan view is preferably 1 or more, and is preferably 15 or less, more preferably 12 or less.

Industrial Applicability [0073]

According to the present invention, a pull-on disposable diaper is provided that has excellent air permeability, and can prevent leakage of a waste liquid while effectively preventing a build-up of moisture and skin issues.

Claims

1. A pull-on disposable diaper comprising:

2. The pull-on disposable diaper according to claim 1, wherein the top sheet overlaps the longitudinal end portion of the absorbent member that is present in the outer cover shrinkable region, as viewed in a plan view.

3. The pull-on disposable diaper according to claim 1 or 2, wherein the absorbent member includes an absorbent core that contains an absorbent material, the top sheet includes a portion that extends outward in the longitudinal direction from a longitudinal end portion of the absorbent core, and the extension portion of the top sheet overlaps the below-waist elastic members as viewed in a plan view.

4. The pull-on disposable diaper according to any one of claims 1 to 3, wherein the through holes include a through hole that is present between the longitudinal end portion of the absorbent member and one of the plurality of below-waist elastic members that is not overlapped by the longitudinal end portion of the absorbent member and is closest to the longitudinal end portion of the absorbent member as viewed in a plan view.

5. The pull-on disposable diaper according to any one of claims 1 to 4, wherein both the outer layer sheet and the inner layer sheet include the plurality of through holes, and at least some of the through holes of the outer layer sheet and the inner layer sheet overlap with each other.

6. The pull-on disposable diaper according to any one of claims 1 to 5, wherein in the outer cover shrinkable region, the outer layer sheet and the inner layer sheet are bonded to each other at a plurality of outer cover bonding portions that are intermittently provided in both the longitudinal direction and the lateral direction, and the below-waist elastic members are provided so as to not pass through the outer cover bonding portions.

7. The pull-on disposable diaper according to claim 5 or 6, wherein, in the outer cover shrinkable region, the outer layer sheet and the inner layer sheet are bonded to each other at a plurality of outer cover bonding portions that are intermittently provided in both the longitudinal direction and the lateral direction, and the through holes extend through the outer cover bonding portions in the thickness direction.

8. The pull-on disposable diaper according to any one of claims 1 to 7, wherein the outer layer sheet further includes, in addition to a portion that has the same shape and dimensions as those of the inner layer sheet, a front extension portion that extends outward from an end portion in the longitudinal direction on the front portion side of the inner layer sheet when the outer layer sheet and the inner layer sheet are stacked, and a rear extension portion that extends outward from an end portion in the longitudinal direction on the rear portion side of the inner layer sheet.

9. The pull-on disposable diaper according to claim 8, wherein the front extension portion and the rear extension portion are each folded over the inner layer sheet so as to cover both longitudinal end portions of the absorbent assembly that is fixedly provided on the inner layer sheet, and are fixed.

10. The pull-on disposable diaper according to claim 8 or 9, wherein, in the outer cover shrinkable region, the skin-facing surface of the top sheet is covered with a hydrophobic sheet, and the hydrophobic sheet serves as the front extension portion or the rear extension portion.

11. The pull-on disposable diaper according to any one of claims 1 to 9, wherein, in the outer cover shrinkable region, the skin-facing surface of the top sheet is covered with a hydrophobic sheet.

12. The pull-on disposable diaper according to claim 10 or 11, wherein the hydrophobic sheet is bonded to the top sheet at the projections, but is not bonded to the top sheet at the depressions.

13. The pull-on disposable diaper according to claim 12, wherein bonding portions at which the hydrophobic sheet and the top sheet are bonded are intermittently provided in the longitudinal direction.

14. The pull-on disposable diaper according to any one of claims 10 to 13, wherein an inner-side end portion of the hydrophobic sheet in the longitudinal direction is a free end portion that is not bonded to the top sheet.

15. The pull-on disposable diaper according to any one of claims 10 to 14, wherein the hydrophobic sheet is made of a non-woven fabric that is stretchable in the lateral direction.

16. The pull-on disposable diaper according to any one of claims 10 to 15, wherein the hydrophobic sheet is bonded to the top sheet at peaks of the projections, but is not bonded to the top sheet at the depressions.

17. The pull-on disposable diaper according to any one of claims 1 to 16, wherein each of the front portion and the rear portion is divided in the longitudinal direction into an absorbent assembly-absent region in which the absorbent assembly is not provided and an absorbent assembly-present region that is located on an inner side of the absorbent assembly-absent region in the longitudinal direction, and the below-waist elastic members are provided in both the absorbent assembly-absent region and the absorbent assembly-present region.

18. The pull-on disposable diaper according to claim 17, wherein the outer cover shrinkable region is formed over an entire area of each of the absorbent assembly-absent region and the absorbent assembly-present region, and is also formed in an overlapping area of the absorbent assembly-present region that overlaps the absorbent assembly as viewed in a plan view.

19. The pull-on disposable diaper according to any one of claims 1 to 18, wherein the outer cover shrinkable region has, on the non-skin-facing surface side, an uneven structure in which ridge portions and groove portions that extend in the longitudinal direction are alternately provided in the lateral direction.

20. The pull-on disposable diaper according to claim 19, wherein, in the outer cover shrinkable region, the ridge portions on the skin-facing surface side and the ridge portions on the non-skin-facing surface side are located at the same positions in the lateral direction, and the groove portions on the skin-facing surface side and the groove portions on the non-skin-facing surface side are located at the same positions in the lateral direction.

21. The pull-on disposable diaper according to any one of claims 1 to 20, wherein the both lateral side edge portions of the outer cover in the front portion and the both lateral side edge portions of the outer cover in the rear portion are bonded to form a pair of side seal portions, and the plurality of below-waist elastic members are each bonded to both the outer layer sheet and the inner layer sheet only at the side seal portions or portions near the side seal portions, but are not bonded to the both sheets at other portions.

22. The pull-on disposable diaper according to any one of claims 1 to 21, wherein, when the diaper is in its natural state or worn state, each of the outer layer sheet and the inner layer sheet forms a plurality of folds that span across the plurality of below-waist elastic members, and extend continuously in the longitudinal direction, the folds function as the ridge portions, and spaces between the folds that are adjacent in the lateral direction function as the groove portions.

23. The pull-on disposable diaper according to any one of claims 1 to 22, wherein, in each of the groove portions, the plurality of through holes are intermittently provided at a predetermined spacing in the longitudinal direction.

24. The pull-on disposable diaper according to any one of claims 1 to 23, wherein both of the outer layer sheet and the inner layer sheet include the plurality of through holes, and all of the through holes of the outer layer sheet and the inner layer sheet overlap in one-to-one correspondence with each other.

25. The pull-on disposable diaper according to any one of claims 1 to 24, wherein, in the outer cover shrinkable region, the outer layer sheet and the inner layer sheet are bonded to each other at a plurality of outer cover bonding portions that are intermittently provided in both of the longitudinal direction and the lateral direction, both the outer layer sheet and the inner layer sheet include the plurality of through holes, and one of the through holes of the outer layer sheet overlaps one of the through holes of the inner layer sheet at a position of one of the outer cover bonding portions.

26. The pull-on disposable diaper according to any one of claims 1 to 25, wherein the through holes each have a maximum length as viewed in a plan view of 1 mm or more and 5 mm or less.

27. The pull-on disposable diaper according to any one of claims 1 to 26, wherein the number of the through holes per unit area in the outer cover shrinkable region is 1 or more and 15 or less based on an area of a 10 mm square-shaped region as viewed in a plan view.

28. The pull-on disposable diaper according to any one of claims 1 to 27, wherein with regard to at least some of the plurality of depressions of the top sheet, the groove portions of the outer cover shrinkable region are present on extension lines of the depressions in the longitudinal direction.

29. The pull-on disposable diaper according to any one of claims 1 to 28, wherein each of the plurality of depressions in the skin-facing surface of the top sheet is in one-to-one correspondence with a corresponding one of the plurality of groove portions in the outer cover shrinkable region, and is at the same position in the lateral direction as the corresponding one of the groove portions.

30. The pull-on disposable diaper according to any one of claims 1 to 29, wherein, in the skin-facing surface of the top sheet, a separation distance between peaks of the projections that are adjacent in the lateral direction is 1.5 mm or more and 5 mm or less.

31. The pull-on disposable diaper according to any one of claims 1 to 30, wherein the depressions each have a length in the longitudinal direction of 7 mm or more and 60 mm or less.

32. The pull-on disposable diaper according to any one of claims 1 to 31, wherein the number of the below-waist elastic members that are present in the front portion or the rear portion is 10 or more and 35 or less.

33. The pull-on disposable diaper according to any one of claims 1 to 32, wherein, in the front portion or the rear portion, the number of below-waist elastic members that pass through a portion that overlaps with the absorbent member, and cross the absorbent member in the lateral direction as viewed in a plan view is 1 or more and 15 or less.