GB2561118A

GB2561118A - Disposable diaper

Info

Publication number: GB2561118A
Application number: GB1810359.8A
Authority: GB
Inventors: Koyama Izumi; Fukuda Yuko; Kajiwara Jun; Okuda Yasuyuki
Original assignee: Kao Corp
Current assignee: Kao Corp
Priority date: 2015-12-22
Filing date: 2016-11-30
Publication date: 2018-10-03
Anticipated expiration: 2036-11-30
Also published as: JP2017113188A; CN108430414A; CN108430414B; GB201810359D0; JP6208209B2; DE112016005893T5; WO2017110396A1; RU2678010C1; GB2561118B

Abstract

This disposable diaper (1) has abdominal waist flaps (FA) and back waist flaps (FB) located to the outside of the front and back ends (23A, 23B) in the longitudinal direction (X) of an absorbent (23) and extending in the transverse direction (Y). The back waist flaps (FB) have a hydrophobic skin-side sheet (4) and a hydrophilic non-skin-side sheet (5). The skin-side sheet (4) is provided with depressions (41) that form hollows toward the non-skin-side sheet (5) and fused areas (42) on the apices inside the depressions (41). The fused areas (42) comprise portions in which the fibers configuring the skin-side sheet (4) have been melted and the constituent fibers are fused to each other without gaps. The basis weight of the skin-side sheet (4) is 30 g/m2 or less. The thickness of the fused areas (42) is 1/3 or less of the thickness of portions of the skin-side sheet (4) exclusive of the depressions (41).

Description

(56) Documents Cited:

JP 2012162842 A JP4190332 B2 (58) Field of Search:

INT CLA61F

A61F 13/511 (2006.01)

JP 2001327534 A (86) International Application Data:

PCT/JP2016/085629 Ja 30.11.2016 (87) International Publication Data:

WO2017/110396 Ja 29.06.2017

Other: Jitsuyo Shinan Koho 1922-1996, Jitsuyo Shinan Toroku Koho 1996-2017, Kokai Jitsuyo Shinan Koho 1971-2017, Toroku Jitsuyo Shinan Koho 1994-2017 (71) Applicant(s):

Kao Corporation (Incorporated in Japan)

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

Izumi Koyama Yuko Fukuda Jun Kajiwara Yasuyuki Okuda (74) Agent and/or Address for Service:

Withers & Rogers LLP

More London Riverside, LONDON, SE1 2AU, United Kingdom (54) Title ofthe Invention: Disposable diaper Abstract Title: Disposable diaper (57) This disposable diaper (1) has abdominal waist flaps (FA) and back waist flaps (FB) located to the outside ofthe front and back ends (23A, 23B) in the longitudinal direction (X) of an absorbent (23) and extending in the transverse direction (Y). The back waist flaps (FB) have a hydrophobic skin-side sheet (4) and a hydrophilic non-skin-side sheet (5). The skin-side sheet (4) is provided with depressions (41) that form hollows toward the non-skin-side sheet (5) and fused areas (42) on the apices inside the depressions (41). The fused areas (42) comprise portions in which the fibers configuring the skin-side sheet (4) have been melted and the constituent fibers are fused to each other without gaps. The basis weight of the skin-side sheet (4) is 30 g/m2 or less. The thickness of the fused areas (42) is 1/3 or less of the thickness of portions of the skin-side sheet (4) exclusive of the depressions (41).

¥

This international application has entered the national phase early.

1/3

FIG. 1

CL1 Β

Y

2/3

FIG. 2

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A

Β

23Β

3/3

FIG. 3

DESCRIPTION

Title of Invention: DISPOSABLE DIAPER

Technical Field [0001]

The present invention relates to a disposable diaper.

Background Art [0002]

Disposable diapers include so-called pull-on disposable diapers in which an outer cover is provided on the outer side of an oblong absorbent assembly including an absorbent member. The applicant of the present invention previously proposed a technique for effectively preventing eczema, heat rashes, rashes, and the like by allowing sweat to be absorbed by a hydrophilic nonwoven fabric that is additionally provided on a skin-facing surface of an outer cover of such a pull-on disposable diaper (Patent Literature 1, for example).

[0003]

Furthermore, Patent Literature 2 discloses a disposable diaper whose end flaps and side flaps are provided with a composite sheet in which a hydrophobic first fiber nonwoven fabric on the skin-contacting surface and a hydrophilic second fiber nonwoven fabric on the non-skin-contacting surface are laminated on each other, in order to absorb sweat. Patent Literature 2 describes that the composite sheet is provided with a large number of fusion bonded portions depressed from the skin-contacting surface toward the non-skin-contacting surface.

[0004]

Furthermore, Patent Literature 3 discloses an absorbent article such as a disposable diaper using a fluid permeable topsheet in which ridge portions and trough portions extending the longitudinal direction are alternately arranged in the lateral direction in order to absorb sweat, wherein compressed portions formed by compressing constituent fibers together are formed on the ridge portions of the fluid permeable topsheet.

Citation List

Patent Literatures [0005]

Patent Literature 1: JP 2004-358099A

Patent Literature 2: JP 2004-298467A

Patent Literature 3: JP 2012-162842A

Summary of Invention [0006]

The present invention is directed to a disposable diaper comprising, in a longitudinal direction, a front region, a rear region, and a crotch region positioned between the front region and the rear region, having an absorbent member spanning from the front region to the rear region, and having a front waist flap and a rear waist flap extending in a lateral direction and positioned outward of front and rear end portions, respectively, in the longitudinal direction of the absorbent member. At least the rear waist flap has a hydrophobic skin-side sheet that forms a skin-contacting surface, and a hydrophilic non-skin-side sheet that is positioned on a non-skin-facing surface side of the skin-side sheet. The skin-side sheet includes a plurality of depressed portions depressed toward the non-skin-side sheet, and bonded portions at top sections in the respective depressed portions. The bonded portions include portions in which constituent fibers of the skin-side sheet are melted and bonded to each other with no gap therebetween. A basis weight of the skin-side sheet is 30 g/m² or less. A thickness of the bonded portions in the depressed portions is 1/3 or less of a thickness of portions other than the depressed portions in the skin-side sheet.

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

[FIG. 2] FIG. 2 is an unfolded plan view of the diaper shown in FIG. 1 in its flat-out, uncontracted state, viewed from the skin-contacting surface side.

[FIG. 3] FIG. 3 is a cross-sectional view taken along line III-ΠΙ shown in FIG. 2.

[FIG. 4] FIG. 4 is an enlarged cross-sectional view showing a cross-section taken along the lateral direction (Y direction) of a waist elasticized portion in the diaper shown in FIG.

1.

Description of Embodiments [0008]

The disposable diaper described in Patent Fiterature 1 is such that the nonwoven fabric for absorbing sweat is hydrophilic, and thus the sweat may be retained in the nonwoven fabric. Accordingly, there is room for improvement for more effectively preventing eczema, heat rashes, rashes, and the like.

[0009]

Furthermore, the fusion bonded portions and the compressed portions described in Patent Fiteratures 2 and 3 are such that these portions are formed while maintaining the fiber form of their constituent fibers in order to shift sweat therefrom as well through capillary action. If fusion bonded portions and compressed portions are formed while maintaining the fiber form of their constituent fibers in this manner, the thickness of peripheral edges of the fusion bonded portions cannot be sufficiently thin, the capillary action is unstable, and thus sweat cannot be sufficiently absorbed.

[0010]

The present invention relates to a disposable diaper that can solve the above-mentioned problems in the related art.

[0011]

Hereinafter, the present invention will be described with reference to the drawings on the basis of preferred embodiments thereof.

The disposable diaper of the present invention includes, along a longitudinal direction X, a front region A, a rear region B, and a crotch region C that is positioned between the front region A and the rear region B, has an absorbent member 23 spanning from the front region A to the rear region B, and has a front waist flap FA and a rear waist flap FB extending in the lateral direction Y and positioned outward of front and rear ends 23 A and 23B, respectively, in the longitudinal direction X of the absorbent member 23. The front region A is a region that is worn about a front side of a wearer when the disposable diaper is worn, and the rear region B is a region that is worn about a rear side of the wearer when the disposable diaper is worn. The front waist flap FA refers to a region obtained by adding a region extending in the lateral direction Y and positioned outward in the longitudinal direction X from an edge of the front end 23A on the front region A side in the longitudinal direction X of the absorbent member 23 and regions extending in the lateral direction Y from the front end 23A on the front region A side in the longitudinal direction X of the absorbent member 23. Furthermore, the rear waist flap FB refers to a region obtained by adding a region extending in the lateral direction Y and positioned outward in the longitudinal direction X from an edge of the rear end 23B on the rear region B side in the longitudinal direction X of the absorbent member 23 and regions extending in the lateral direction Y from the rear end 23B on the rear region B side in the longitudinal direction X of the absorbent member 23.

[0012]

FIGS. 1 and 2 show a pull-on disposable diaper 1 (hereinafter, alternatively referred to as a “diaper 1”) that is a disposable diaper according to an embodiment of the present invention. As shown in FIGS. 1 and 2, the diaper 1 includes an absorbent assembly 2, and an outer cover 3 that is arranged on the non-skin-facing surface side of the absorbent assembly 2 and fixes the absorbent assembly 2. The outer cover 3 has the front waist flap FA and the rear waist flap FB extending in the lateral direction Y and positioned outward of the front and rear ends 23A and 23B, respectively, in the longitudinal direction X of the absorbent member 23 forming the absorbent assembly 2. The diaper 1 is a disposable diaper in which both lateral side edges 3al,3al of the front region A of the outer cover 3 and both lateral side edges 3b 1,3b 1 of the rear region B of the outer cover 3 are joined to each other, and form a pair of side seals S,S, a waist opening WO, and a pair of leg openings LO,LO. Preferably, as shown in FIG. 2, in plan view of the diaper 1 in its flat-out, uncontracted state, the outer cover 3 is divided into the front region A that is worn about a front side of a wearer when worn, the rear region B that is worn about a rear side of the wearer when worn, and the crotch region C that is positioned between the front region A and the rear region B.

[0013]

The above-described flat-out, uncontracted state of the diaper 1 is, as shown in FIG. 2, a state in which the side seals S are peeled away so that the diaper 1 is in a flat-out state, elastic members at respective portions of the diaper 1 in the flat-out state are uncontracted so that the dimensions of the diaper matches its design dimensions (that is the same as the dimensions when the diaper 1 is spread out in a planar shape while completely eliminating the influence of the elastic members).

[0014]

In this specification, “skin-contacting surface” refers to a surface of the diaper 1 or a constituent element thereof (e.g., the outer cover 3) that is in contact with the skin of the wearer when the diaper 1 is worn. Furthermore, “skin-facing surface” is a surface of the diaper 1 or a constituent element thereof that faces the skin of the wearer when the diaper 1 is worn, and “non-skin-facing surface” is a surface of the diaper 1 or a constituent element thereof that faces the side opposite to the skin of the wearer (clothing side) when the diaper 1 is worn. In the diaper 1, the longitudinal direction (X direction) is a direction from the front region A to the rear region B in plan view of the diaper 1 in its flat-out, uncontracted state. Furthermore, the lateral direction (Y direction) is a direction that is orthogonal to the longitudinal direction (X direction) and is the width direction of the diaper 1 in plan view of the diaper 1 in its flat-out, uncontracted state.

Furthermore, the diaper 1 is bilaterally symmetric about a longitudinal center line CL1 extending in the longitudinal direction (X direction) shown in FIG. 2. A CL2 in FIG. 2 is a lateral center line extending in the lateral direction (Y direction) and dividing the diaper 1 into two halves, and is orthogonal to the longitudinal center line CL1.

[0015]

In the diaper 1, as shown in FIG. 2, the absorbent assembly 2 has an oblong shape that is relatively oblong in the longitudinal direction (X direction) in the flat-out, uncontracted state of the diaper 1. The absorbent assembly 2 includes a liquid permeable topsheet 21 that forms the skin-facing surface, a sparingly liquid permeable (or water repellent) backsheet 22 that forms the non-skin-facing surface, and a liquid-retentive absorbent member 23 that is positioned between the sheets 21 and 22. Furthermore, as shown in FIG. 2, leak-proof cuff's 24,24 having leak-proof cuff forming elastic members 25 arranged in a state of being stretched in the longitudinal direction (X direction) are provided on both sides along the longitudinal direction (X direction) of the absorbent assembly 2. Specifically, the leak-proof cuff's 24 are made of a liquid impermeable or water repellent and air permeable material, and the leak-proof cuff forming elastic members 25 are arranged in a state of being stretched in the longitudinal direction (X direction), near free ends of the leak-proof cuff's 24. When the diaper is worn, the free ends of the leak-proof cuff's 24 stand up due to contraction of the leak-proof cuff forming elastic members 25, thereby preventing a bodily fluid from flowing out in the lateral direction (Y direction).

[0016]

As shown in FIG. 2, the thus configured absorbent assembly 2 is joined to the middle of the outer cover 3 using an assembly fixing adhesive such that the longitudinal direction (X direction) of the absorbent assembly 2 matches the longitudinal direction (X direction) of the diaper 1 in its flat-out, uncontracted state. In this manner, the outer cover 3 is arranged on and adhesively fixed to the non-skin-facing surface side of the backsheet 22 forming the absorbent assembly 2 in the thickness direction of the disposable diaper 1. Accordingly, in the diaper 1, the absorbent member 23 forming the absorbent assembly 2 is arranged spanning from the front region A to the rear region B.

[0017]

At least the rear waist flap FB of the front waist flap FA and the rear waist flap FB extending in the lateral direction Y and positioned outward of the front and rear ends 23A and 23B, respectively, in the longitudinal direction X of the absorbent member 23 includes a hydrophobic skin-side sheet 4 that forms the skin-contacting surface, and a hydrophilic non-skin-side sheet 5 that is positioned on a non-skin-facing surface side of the skin-side sheet 4. As shown in FIG. 2, in the diaper 1, the front waist flap FA and the rear waist flap FB have a skin-side sheet 4 and the non-skin-side sheet 5, and further have a hydrophobic outer sheet 6 on the non-skin-facing surface side of the non-skin-side sheet

5.

[0018]

Preferably, as shown in FIG. 2, in the diaper 1, the outer cover 3 includes the front waist flap FA and the rear waist flap FB extending in the lateral direction Y and positioned outward of the front and rear ends 23A and 23B, respectively, in the longitudinal direction X of the absorbent member 23. As shown in FIGS. 2 and 3, the outer cover 3 includes the outer sheet 6 on the non-skin-facing surface side that forms the outer face of the diaper 1, skin-side sheets 4 on the side that is closest to the skin-facing surface, and an inner sheet that is positioned between the outer sheet 6 and the skin-side sheet 4. In the diaper 1, the inner sheet corresponds to the non-skin-side sheet 5.

[0019]

More preferably, as shown in FIG. 2, in the diaper 1, the sheet material forming the outer sheet 6 in both the front region A and the rear region B is folded back toward the skin-facing surface of the non-skin-side sheet 5 along the peripheral edges of the waist openings WO, and the folded-back portions 6R cover the front and rear ends 23 A and 23B in the longitudinal direction (X direction) of the absorbent member 23 forming the absorbent assembly 2. The skin-side sheets 4, the non-skin-side sheet (inner sheet) 5, and the outer sheet 6 may be separate sheets, but, in the diaper 1, the skin-side sheets 4 are formed of the folded-back portions 6R of the outer sheet 6. In this manner, in the diaper 1, the skin-side sheets 4 are arranged on the skin-facing surface side of the non-skin-side sheet 5 in the rear waist flap FB and the front waist flap FA. As shown in FIG. 2, in the diaper 1, the outer sheet 6 other than the folded-back portions 6R and the non-skin-side sheet 5 are inwardly narrowed toward the longitudinal center line CL1 at the middle in the longitudinal direction (X direction), and are formed so as to have the same shape and the same size. The skin-side sheets 4 formed of the folded-back portions 6R of the outer sheet 6 are each formed in the shape of a rectangle that is elongated in the lateral direction (Y direction).

[0020]

As shown in FIG. 3, the skin-side sheets 4 include a plurality of depressed portions 41 depressed toward the non-skin-side sheet 5, and bonded portions 42 at the top sections in the respective depressed portions 41. The bonded portions 42 include portions in which constituent fibers of the skin-side sheets 4 are melted and bonded to each other with no gap therebetween. The portions that are bonded refer to portions in which constituent fibers are melted with no gap therebetween to the extent that the constituent fibers do not return to their original fiber shape even when peeled away from the portions that are bonded. The portions that are bonded are liquid impermeable portions that do not allow liquids to pass therethrough. In the bonded portions 42 of the diaper 1, the portions that are bonded are made into a film and takes the form of a film. The form of a film refers to a state in which fibers are melted to the level that their original shape becomes vague.

[0021]

In order to improve the sweat absorbing properties, the bonded portions 42 are arranged in the skin-side sheets 4, preferably at least on the side positioned outward in the longitudinal direction X of the edge of the rear end 23B (on the side opposite to the lateral center line CL2) in the longitudinal direction (X direction) of the absorbent member 23 forming the absorbent assembly 2, and, in the diaper 1, the bonded portions 42 are intermittently arranged throughout the skin-side sheets 4 as shown in FIG. 2. Preferably, the bonded portions 42 are intermittently arranged in a row along the longitudinal direction (X direction), and a plurality of bonded portion rows 42L formed of the plurality of bonded portions 42 are arranged at intervals along the lateral direction (Y direction). In order to improve the sweat dispersing properties, as shown in FIG. 2, the bonded portions 42 are preferably arranged at positions that do not overlap joined regions 8, which will be described later, and, in the diaper 1, the bonded portion rows 42L and later-described joined region rows 8L formed of the plurality of joined regions 8 are alternately arranged in the lateral direction (Y direction).

[0022]

As shown in FIG. 3, the bonded portions 42 can be formed by heat embossing only the skin-side sheets 4 so that the skin-side sheets 4 are melted and solidified. The heat embossing apparatus may be an apparatus including an embossing roller and an anvil roller, wherein the outer circumferential face of the embossing roller has a projection that conforms to the bonded portions 42. As processing for forming the bonded portions 42, ultrasonic sealing, a laser, and the like may be used instead of heat embossing. When forming the bonded portions 42 through heat embossing, the embossing intensity when forming the bonded portions 42 is preferably higher than the embossing intensity when forming the joined regions 8, which will be described later.

[0023]

In order to improve the sweat absorbing properties and not to allow sweat to return from the non-skin-side sheet to the skin, in plan view of the diaper 1 in its flat-out, uncontracted state as shown in FIG. 2, the interval between the bonded portions 42,42 that are adjacent to each other in the longitudinal direction (X direction) and that form the bonded portion rows 42L extending in the longitudinal direction (X direction) is preferably 1 mm or greater, and more preferably 3 mm or greater, is preferably 20 mm or less, and more preferably 18 mm or less, and, specifically, is preferably from 1 to 20 mm, and more preferably from 3 to 18 mm.

Furthermore, in order to improve the sweat dispersing properties, in plan view of the diaper 1 in its flat-out, uncontracted state as shown in FIG. 2, the interval between the bonded portion rows 42L,42L that are adjacent to each other in the lateral direction (Y direction) is preferably 4 mm or greater, and more preferably 6 mm or greater, is preferably 20 mm or less, and more preferably 16 mm or less, and, specifically, is preferably from 4 to 20 mm, and more preferably from 6 to 16 mm.

[0024]

The basis weight of the skin-side sheets 4 is 30 g/m² or less, and is preferably 20 g/m² or less in order to shift the wearer’s sweat toward the non-skin-side sheet 5, is preferably 9 g/m² or greater, and more preferably 10 g/m² or greater, in order to allow the skin-side sheets 4 to secure a space between the non-skin-side sheet 5 that has absorbed liquid and the skin, thereby further reliably preventing the wearer’s sweat that has been shifted to the non-skin-side sheet 5 from returning to the skin and preventing the sheet that has absorbed sweat from sticking to the skin, and is preferably 30 g/m² or less, and more preferably 20 g/m² or less. Specifically, the basis weight is preferably from 9 to 30 g/m², and more preferably from 10 to 20 g/m². The basis weight of the skin-side sheets 4 can be measured from the area and the weight of a sheet that can be measured. This measurement is performed at 23 ± 2°C and a relative humidity of 50 ± 5% on a sample that has been stored in the same environment for 24 hours or more before measurement.

[0025]

Furthermore, each bonded portion 42 in the depressed portions 41 included in the skin-side sheets 4 has a thickness dl (see FIG. 3) that is 1/3 or less, and, in order to shift the wearer’s sweat toward the non-skin-side sheet 5, is 1/4 or less, and more preferably 1/5 or less, of a thickness d2 (see FIG. 3) of portions other than the depressed portions 41 in the skin-side sheets 4, and the lower limit thereof is 1/30.

Specifically, the thickness dl (see FIG. 3) of the bonded portions 42 is preferably 60 pm or less, and more preferably 45 pm or less, and the lower limit thereof is 10 pm, from the same point of view.

The thickness dl of each bonded portion 42 is measured by cutting the sheet including a bonded portion 42 in the thickness direction using a knife, a cutter, a razor, or the like such that the cut face of the bonded portion 42 does not collapse, and observing the cut cross-section using a microscope, thereby measuring the thickness of the thickest portion. The thickness is measured at ten different bonded portions 42, and an average thereof is calculated as the thickness of the bonded portions 42.

Furthermore, from the same point of view, the thickness d2 (see FIG. 3) of portions other than the depressed portions 41 in the skin-side sheets 4 is preferably 600 pm or less, and more preferably 350 pm or less, and the lower limit thereof is 100 pm.

The thickness d2 of portions other than the depressed portions 41 included in the skin-side sheets 4 is measured using a thickness gauge in a state where 0.05 kPa of pressure is applied to the skin-side sheets 4. A laser displacement gauge manufactured by Omron Corporation is used as a thickness gauge. The thickness is measured at ten points, and an average thereof is calculated as the thickness of portions other than the depressed portions 41.

[0026]

Furthermore, as shown in FIG. 3, an outer periphery 43 of each bonded portion 42 in the depressed portions 41 included in the skin-side sheets 4 has a thickness that gradually becomes thinner toward the bonded portion 42. Preferably, each outer periphery 43 is formed in the shape of a ring along the outer periphery of the bonded portion 42 in the depressed portion 41. The ring-shaped outer periphery 43 has a thickness that is thinner on the inner side located closer to the bonded portion 42 than on the outer side and that gradually becomes thinner from the outer side toward the inner side located closer to the bonded portion 42. In order to shift the wearer’s sweat toward the non-skin-side sheet 5, when the depth of each depressed portion 41 in the bonded portions 42 is taken as d3 (see FIG. 3), the thickness at a position that is distanced outward from the end of the bonded portion 42 by a distance that is 0.50 times the depth (d3) is preferably from 20 to 75%, and more preferably from 30 to 65%, of the thickness d2 of portions other than the depressed portions 41. The thickness at a position that is distanced outward from the end of the bonded portion 42 by a distance that is 1.5 times the depth (d3) is preferably from 55 to 95%, and more preferably from 70 to 90%, of the thickness d2 of the portions other than the depressed portions 41. The depth (d3) of the depressed portions 41 and the thickness at a position that is distanced therefrom are measured according to a method similar to that for the thickness dl of the bonded portions 42.

Since the thickness at a position that is distanced outward from the end of the bonded portion 42 by a distance that is 0.50 times the depth (d3) is smaller than the thickness at a position that is distanced outward from the end of the bonded portion 42 by a distance that is 1.5 times the depth (d3), it is seen that the ring-shaped outer periphery 43 has a thickness that is thinner on the inner side located closer to the bonded portion 42 than on the outer side and that gradually becomes thinner from the outer periphery 43 toward the inner side located closer to the bonded portion 42.

[0027]

Furthermore, the skin-side sheets 4 and the non-skin-side sheet 5 may be fixed to each other in the outer cover 3, for example, via the joined regions 8 through heat embossing, which will be described later, but, in the diaper 1, they are bonded to each other via an adhesive 9 as shown in FIG. 3. The adhesive 9 is applied to the non-skin-facing surface of the skin-side sheets 4 or the skin-facing surface of the non-skin-side sheet 5, for example, in the form of a spiral. In order to shift the wearer’s sweat toward the non-skin-side sheet 5, the position at which the adhesive 9 is arranged preferably overlaps some of the bonded portions 42 in the depressed portions 41 included in the skin-side sheets 4 when viewed in a cross-section as in FIG. 3.

[0028]

Furthermore, in the diaper 1, as shown in FIG. 2, the outer cover 3 has a plurality of elastic members 71 arranged in a state of being stretched in the lateral direction (Y direction) between the non-skin-side sheet 5 and the outer sheet 6 and intermittently arranged along the longitudinal direction (X direction). In the diaper 1, waist elasticized portions G1 and below-waist lower elasticized portions G2 are formed by providing the plurality of elastic members 71. Furthermore, in the diaper 1, as shown in FIG. 2, a plurality of leg elastic members 72 in a stretched state are arranged between the non-skin-side sheet 5 and the outer sheet 6. In the diaper 1, leg elasticized portions G3 are formed by providing the plurality of leg elastic members 72.

[0029]

As shown in FIG. 2, in the diaper 1, the waist elasticized portions G1 are formed in the end flaps that are positioned outward in the longitudinal direction X of the edges of the front and rear ends 23 A and 23B in the longitudinal direction (X direction) of the absorbent member 23 forming the absorbent assembly 2 (on the side opposite to the lateral center line CL2), in the longitudinal direction (X direction). Furthermore, in the diaper 1, the below-waist lower elasticized portions G2 are formed in the side flaps that are positioned between lower ends on the lateral center line CL2 side of the waist elasticized portions G1 and lower ends of the side seals S, in the longitudinal direction (X direction). The rear waist flap FB and the front waist flap FA described above are regions obtained by adding the end flaps (the waist elasticized portions Gl) and part of the side flaps (the below-waist lower elasticized portions G2). Furthermore, as shown in FIG. 2, in the diaper 1, the leg elasticized portions G3 are formed along the peripheral edges of the leg openings LO.

[0030]

As shown in FIG. 2, in the diaper 1, the outer cover 3 includes the plurality of joined regions 8 that join the non-skin-side sheet 5 and the outer sheet 6. As described above, in the diaper 1, the joined regions 8 are not formed on the skin-side sheets 4. In the diaper 1, the rear waist flap FB and the front waist flap FA are formed by joining and fixing the non-skin-side sheet 5 and the outer sheet 6 to each other via the plurality of joined regions 8 through fusion bonding arranged in a dispersed manner.

[0031]

Preferably, as shown in FIG. 2, in the diaper 1, the joined regions 8 between the non-skin-side sheet 5 and the outer sheet 6 are intermittently arranged in a row along the longitudinal direction (X direction) in a region spanning from the waist elasticized portion G1 to the below-waist lower elasticized portion G2 of each of the front region A and the rear region B, and a plurality of joined region rows 8L formed of the plurality of joined regions 8 are arranged at intervals along the lateral direction (Y direction).

[0032]

The joined regions 8 are formed by laminating the non-skin-side sheet 5 and the outer sheet 6, and performing heat embossing such that the laminated portions are melted and solidified, and fusion bonded to each other. The heat embossing apparatus may be an apparatus including an embossing roller and an anvil roller, wherein the outer circumferential face of the embossing roller has a projection that conforms to the joined regions 8. As processing for forming the joined regions 8, ultrasonic sealing, a laser, and the like may be used instead of heat embossing.

[0033]

In order to improve the sweat dispersing properties, in the diaper 1, the interval between joined regions 8,8 that are adjacent to each other in the longitudinal direction (X direction) forming the joined region rows 8L extending in the longitudinal direction (X direction) is preferably 1 mm or greater, and more preferably 3 mm or greater, is preferably 20 mm or less, and more preferably 18 mm or less, and, specifically, is preferably from 1 to 20 mm, and more preferably from 3 to 18 mm.

Furthermore, in order to improve the ability to evaporate sweat that has been absorbed, the interval between joined region rows 8L,8L that are adjacent to each other in the lateral direction (Y direction) is preferably 4 mm or greater, and more preferably 6 mm or greater, is preferably 20 mm or less, and more preferably 16 mm or less, and, specifically, is preferably from 4 to 20 mm, and more preferably from 6 to 16 mm.

[0034]

The diaper 1 includes the plurality of elastic members 71 arranged in a state of being stretched in the lateral direction (Y direction) between the non-skin-side sheet 5 and the outer sheet 6 fixed to each other via the joined regions 8 and intermittently arranged along the longitudinal direction (X direction). Preferably, as shown in FIG. 2, in the diaper 1, in a region spanning from the waist elasticized portion G1 to the below-waist lower elasticized portion G2 of each of the front region A and the rear region B, the plurality of elastic members 71 are arranged in a state of being stretched in the lateral direction (Y direction) through gaps between the joined regions 8 of the plurality of joined region rows 8L. In order to shift the wearer’s sweat toward the non-skin-side sheet 5, the elastic members 71, when viewed in a cross-section as in FIG. 4, are preferably such that the positions where the elastic members 71 are arranged overlap some of the bonded portions 42 in the depressed portions 41 included in the skin-side sheets 4.

[0035]

Furthermore, as shown in FIG. 2, in the diaper 1, a pair of outer-side fixing regions 3T1,3T1 formed by joining the non-skin-side sheet 5 and the outer sheet 6 using an elastic member fixing adhesive are arranged in both lateral side edges 3al,3al of the front region A of the outer cover 3 and both lateral side edges 3b 1,3b 1 of the rear region B of the outer cover 3, and a pair of assembly-side fixing regions 3T2,3T2 formed by joining the non-skin-side sheet 5 and the outer sheet 6 using an elastic member fixing adhesive are arranged near both sides along the longitudinal direction (X direction) of the absorbent assembly 2.

[0036]

In each of the waist elasticized portions G1 of the diaper 1, the plurality of elastic members 71 are arranged spanning between the pair of outer-side fixing regions 3T1,3T1, and the elastic members 71 are fixed between the non-skin-side sheet 5 and the outer sheet 6 in both the pair of outer-side fixing regions 3T1,3T1, but are not fixed to either the non-skin-side sheet 5 or the outer sheet 6 between the pair of outer-side fixing regions 3T1,3T1.

Furthermore, in each of the below-waist lower elasticized portions G2 of the diaper 1, the plurality of elastic members 71 are arranged spanning from the outer-side fixing region 3T1 to the assembly-side fixing region 3T2, and the elastic members 71 are fixed between the non-skin-side sheet 5 and the outer sheet 6 in all the outer-side fixing regions 3T1 and the assembly-side fixing regions 3T2, but are not fixed to either the non-skin-side sheet 5 or the outer sheet 6 between the outer-side fixing regions 3T1 and the assembly-side fixing regions 3T2. In each of the below-waist lower elasticized portions G2 of the diaper 1, the elastic members 71 are not arranged between the pair of assembly-side fixing regions 3T2,3T2, or are arranged therebetween in a state of being finely cut so as not to exert their elasticity.

[0037]

In each of the leg elasticized portions G3 of the diaper 1, the plurality of leg elastic members 72 arranged in a state of being stretched along the peripheral edges of the leg openings LO are fixed between the non-skin-side sheet 5 and the outer sheet 6 via an elastic member fixing adhesive arranged in a planar shape along the peripheral edges of the leg openings LO.

[0038]

As shown in FIGS. 1 and 4, the diaper 1 includes a gather portion G in which the skin-side sheets 4 alternately form projections projecting toward the skin side and depressions depressed toward the non-skin side along the width direction of the diaper 1 due to contraction of the plurality of elastic members 71 arranged in a state of being stretched in the lateral direction (Y direction) between the non-skin-side sheet 5 and the outer sheet 6 and intermittently arranged along the longitudinal direction (X direction). Preferably, in the outer cover 3 of the diaper 1, the gather portion G is formed by the outer sheet 6 between the joined region rows 8L,8L that are adjacent to each other in the lateral direction (Y direction) deforming so as to be warped outward and the skin-side sheets 4 and the non-skin-side sheet 5 fixed to each other via the adhesive 9 deforming so as to be warped inward, due to contraction of the plurality of elastic members 71 arranged in a state of being stretched in the lateral direction (Y direction) between the non-skin-side sheet 5 and the outer sheet 6 and intermittently arranged along the longitudinal direction (X direction), in the waist elasticized portions G1 and the below-waist lower elasticized portions G2. Creases 3F formed of the outer sheet 6 or the skin-side sheets 4 and the non-skin-side sheet 5 are generated between the joined region rows 8L,8L that are adjacent to each other, and hollow portions 3H surrounded by the crease 3F and the crease 3F are formed between the outer sheet 6, and the skin-side sheets 4 and the non-skin-side sheet 5.

[0039]

In order to shift the wearer’s sweat toward the non-skin-side sheet 5, in a cross-section of the gather portion G formed through contraction of the elastic members 71 as shown in FIG. 4, preferably 60% or greater of all of the bonded portions 42, and more preferably 75% or greater of all of the bonded portions 42 are arranged from a position that is at half a depth d4 of the depressions depressed toward the non-skin side of the skin-side sheets 4 to the projection side (the skin-facing surface side), and the upper limit thereof is preferably 100%.

[0040]

Hereinafter, materials for forming the constituent elements of the diaper 1 will be described.

The skin-side sheets 4 are sheets formed of a hydrophobic nonwoven fabric or the like made of a hydrophobic fiber, and the non-skin-side sheet 5 is a sheet formed of a hydrophilic nonwoven fabric or the like made of a hydrophilic fiber.

In the diaper 1, the skin-side sheets 4 forming the outer cover 3 are formed of the folded-back portions 6R of the outer sheet 6, and thus the entire outer sheet 6 including the folded-back portions 6R (the skin-side sheets 4) is formed of a hydrophobic sheet made of a hydrophobic fiber, and the non-skin-side sheet 5 that is separate from the outer sheet 6 is formed of a hydrophilic sheet.

[0041]

The hydrophobic fiber forming the hydrophobic sheet used for the outer sheet 6 (including the skin-side sheets 4) may be a synthetic fiber, and specifically may be those ordinarily used as constituent fibers of various nonwoven fabrics, and examples thereof include: polyolefine fibers such as a polyethylene (PE) fiber and a polypropylene (PP) fiber; fibers using a thermoplastic resin such as polyethylene terephthalate (PET) or polyamide alone; and composite fibers such as core-sheath type and side-by-side type composite fibers.

[0042]

The hydrophilic fiber forming the hydrophilic sheet used for the non-skin-side sheet 5 may be a fiber obtained by hydrophilizing a synthetic fiber, and specifically may be a fiber obtained by treating a hydrophobic synthetic fiber with a hydrophilizing agent, or a fiber obtained by kneading a hydrophilizing agent into a hydrophobic synthetic fiber during production of the hydrophobic synthetic fiber. Furthermore, a composite nonwoven fabric obtained by mixing a naturally hydrophilic fiber such as a natural or semi-natural fiber with a synthetic fiber also may be used. There is no particular limitation on the synthetic fiber, and examples thereof include: polyolefine fibers such as a polyethylene (PE) fiber and a polypropylene (PP) fiber; fibers using a thermoplastic resin such as polyethylene terephthalate (PET) or polyamide alone; and composite fibers such as core-sheath type and side-by-side type composite fibers. There is no particular limitation on the hydrophilizing agent used to hydrophilize a synthetic fiber, as long as it is an ordinary hydrophilizing agent used for hygiene products. Specific examples of the hydrophilic fiber include: natural cellulose fibers such as wood pulps and non-wood pulps such as a cotton pulp and a straw pulp; and regenerated cellulose fibers such as rayon and cupro. Furthermore, examples of the hydrophilic sheet may include hydrophilic clothing in addition to hydrophilic nonwoven fabrics. Examples of the types of hydrophilic nonwoven fabrics include air-through nonwoven fabric, spunbonded nonwoven fabric, heat-rolled nonwoven fabric, spunlaced nonwoven fabric, and meltblown nonwoven fabric.

[0043]

Whether the fiber forming the sheet is hydrophilic or hydrophobic may be determined based on a contact angle of a constituent fiber measured using “Method for Measuring Fiber Contact Angle”, which will be described below. Specifically, if the contact angle is 90° or greater, it is determined that the fiber is a hydrophobic fiber with low hydrophilicity, and, if the contact angle is less than 90°, it is determined that the fiber is a hydrophilic fiber with high hydrophilicity.

[0044]

Method for Measuring Fiber Contact Angle

A contact angle is measured, for example, using a contact angle meter MCA-J manufactured by Kyowa Interface Science Co., Ltd. Specifically, immediately after deionized water (about 20 picoliters) is dropped onto a surface of a fiber forming the outer peripheries 43, the contact angle is measured using the contact angle meter. The measurement is performed at five or more points on fiber forming a portion near the bonded portions 42 or fiber forming a portion near the outer edges of the depressed portions 41, and an average thereof is calculated as the contact angle. Note that the measurement environment temperature is set to 20°C.

[0045]

As the topsheet 21, the backsheet 22, the absorbent member 23, the leak-proof cuffs 24, and the like forming the absorbent assembly 2, various types of members conventionally used for absorbent articles such as disposable diapers can be used without any specific limitation. For example, the topsheet 21 may be a monolayered or multilayered nonwoven fabric, an apertured film, or the like. The backsheet 22 may be a moisture permeable resin film or the like. The absorbent member 23 may be an absorbent core made of absorbent polymer particles and fiber materials wrapped in tissue paper. Furthermore, the leak-proof cuffs 24 may be a water repellent monolayered or multilayered nonwoven fabric, or the like.

[0046]

Examples of the material for forming the elastic members (the leak-proof cuff forming elastic members 25, the elastic members 71, the leg elastic members 72, etc.) include a synthetic rubber, such as styrene-butadiene, butadiene, isoprene, and neoprene, natural rubber, EVA, elastic polyolefin, and polyurethane. With respect to the form of the elastic members, filamentous elastic members (rubber thread, etc.) or string-like elastic members (flat rubber string, etc.) having a rectangular, square, circular, elliptical, or polygonal cross-sectional shape or the like can be preferably used.

[0047]

As the elastic member fixing adhesive for fixing the adhesive 9, the elastic members (the leak-proof cuff forming elastic members 25, the elastic members 71, the leg elastic members 72, etc.), and the assembly fixing adhesive for fixing the outer cover 3, the absorbent assembly 2, and the like, various types of hot melt adhesives and the like conventionally used for absorbent articles such as disposable diapers can be used without any specific limitation.

[0048]

Hereinafter, actions and effects obtained when using the diaper 1 of the foregoing embodiment of the present invention will be described.

As shown in FIGS. 2 and 3, in the diaper 1, at least the rear waist flap FB has a hydrophobic skin-side sheet 4 and the hydrophilic non-skin-side sheet 5, and the hydrophobic skin-side sheet 4 includes the depressed portions 41 depressed toward the non-skin-side sheet 5, and the bonded portions 42 in which constituent fibers of the skin-side sheet 4 are bonded to each other at the top sections in the respective depressed portions 41. The bonded portions 42 include portions in which constituent fibers of the skin-side sheet 4 are melted and bonded to each other with no gap therebetween. Furthermore, the bonded portions 42 having the portions bonded to each other with no gap therebetween have a thickness dl (see FIG. 3) that is 1/3 or less of the thickness d2 (see FIG. 3) of portions other than the depressed portions 41 in the skin-side sheet 4. Accordingly, the fiber density of the bonded portions 42 is higher than the fiber density of the outer peripheries 43 of the bonded portions 42 in the depressed portions 41, and the fiber density of the outer peripheries 43 is higher than the fiber density of portions other than the depressed portions 41. Moreover, the basis weight of the skin-side sheets 4 is 30 g/m² or less. The portions bonded to each other with no gap therebetween are liquid impermeable portions that do not allow liquids to pass therethrough, but are portions with relatively high hydrophilicity, and thus, when the diaper 1 is worn, the wearer’s sweat is likely to be drawn from portions other than the depressed portions 41 toward the depressed portions 41, and sweat is likely to quickly shift from the outer peripheries 43 with high fiber density and thin thickness toward the hydrophilic non-skin-side sheet 5. The thus shifted wearer’s sweat inside the non-skin-side sheet 5 is not likely to return to the hydrophobic skin-side sheets 4 or the skin. In this manner, the wearer’s sweat that has been shifted to the non-skin-side sheet 5 on the non-skin-facing surface side is not likely to come into contact with the skin, and thus skin issues such as eczema, heat rashes, and rashes can be reduced. Furthermore, in the diaper 1, the portions bonded to each other with no gap therebetween are made into a film, and thus the above-described effects are more reliably achieved.

[0049]

Furthermore, in the diaper 1, the outer periphery 43 of each bonded portion 42 in the depressed portions 41 included in the skin-side sheets 4 has a thickness that gradually becomes thinner toward the bonded portion 42 as shown in FIG. 3. That is to say, the inter-fiber distance between constituent fibers gradually becomes smaller toward the bonded portions 42, and thus the above-described effects are more reliably achieved.

[0050]

Furthermore, as shown in FIG. 2, in the diaper 1, the hydrophobic outer sheet 6 is arranged on the non-skin-facing surface side of the non-skin-side sheet 5, and the plurality of elastic members 71 are arranged in a state of being stretched in the lateral direction (Y direction) through gaps between the joined regions 8 of the plurality of joined region rows 8L, in regions spanning respectively from the waist elasticized portions Gl to the below-waist lower elasticized portions G2. As shown in FIG. 4, when the elastic members 71 arranged in a state of being stretched are contracted, the creases 3F formed of the skin-side sheets 4 and the non-skin-side sheet 5, and the outer sheet 6 are generated between the joined region rows 8L,8L that are adjacent to each other, and the hollow portions 3H surrounded by the crease 3F and the crease 3F are formed between the skin-side sheets 4 and the non-skin-side sheet 5, and the outer sheet 6. Accordingly, the ability to evaporate the wearer’s sweat that has been shifted to the non-skin-side sheet 5 is improved, and skin issues such as eczema, heat rashes, and rashes can be further reduced.

[0051]

In order to facilitate the reliable shift of wearer’s sweat to the non-skin-side sheet 5, each bonded portion 42 has an area that is preferably 0.5 mm² or greater, and more preferably 0.75 mm² or greater, is preferably 5 mm² or less, and more preferably 4 mm² or less, and, specifically, is preferably from 0.5 to 5 mm², and more preferably from 0.75 to 4 mm².

[0052]

Furthermore, in order to facilitate the above-described effects, each bonded portion 42 has a perimeter length that is preferably 2 mm or greater, and more preferably 3 mm or greater, is preferably 20 mm or less, and more preferably 15 mm or less, and, specifically, is preferably from 2 to 20 mm, and more preferably from 3 to 15 mm.

[0053]

Furthermore, in order to facilitate the above-described effects, in the rear waist flap FB of the diaper 1, in plan view of the diaper 1 in its flat-out, uncontracted state as shown in FIG. 2, a proportion of the area of all bonded portions 42 with respect to the total area of the skin-side sheets 4 is preferably 1% or greater, and more preferably 3% or greater, is preferably 15% or less, and more preferably 10% or less, and, specifically, is preferably from 1 to 15%, and more preferably from 3 to 10%.

[0054]

Furthermore, in order to facilitate the above-described effects, the contact angle between the skin-side sheets forming the outer peripheries 43 of the bonded portions 42 in the depressed portions 41 and deionized water is preferably smaller on the bonded portion 42 side in the outer peripheries 43 than on the outer edge side of the depressed portions 41 in the outer peripheries 43. More specifically, the skin-side sheets near the bonded portions 42 in the outer peripheries 43 have a contact angle with respect to deionized water that is preferably 120° or less, and more preferably 110° or less. The lower limit thereof is 90°.

Furthermore, the skin-side sheets forming portions near the outer edges of the depressed portions 41 in the outer peripheries 43 have a contact angle with respect to deionized water that is preferably 120° or greater, and more preferably 130° or greater. The upper limit of the contact angle of the thus configured skin-side sheets is 180°.

Furthermore, a difference between the contact angle between portions near the bonded portions 42 in the outer peripheries 43 and deionized water and the contact angle between portions near the outer edges of the depressed portions 41 in the outer peripheries 43 and deionized water is preferably large. More specifically, the difference between the contact angles is preferably 15° or greater, and more preferably 25° or greater.

The contact angle between the skin-side sheets on the bonded portion 42 side in the outer peripheries 43 or the skin-side sheets on the outer edge side of the depressed portions 41 in the outer peripheries 43 and deionized water is measured using the following method. A smaller value of the contact angle measured using the following method indicates higher hydrophilicity.

[0055]

Method for Measuring Contact Angle of Skin-Side Sheet

Measurement was performed using a medium-magnification zoom lens inclined at 90° with respect to a microscope VHX-1000 manufactured by Keyence Corporation. The skin-side sheet cut into a portion with a size of MD direction 150 mm x CD direction 70 mm was used as a measurement sample. The measurement environment was set to 20°C / 50%RH, and the measurement sample was set on a measurement stage with the measurement face being oriented upward such that the skin-side sheet could be observed from the CD direction thereof. Then, 3 pL of deionized water was applied to measurement portions (the bonded portion 42 side in the outer peripheries 43 and the outer edges of the depressed portion 41 side in the outer peripheries 43) of the measurement sample set on the measurement stage, and an image thereof was captured. The contact angle was measured at ten points where observation results of both or one end of a water drop on the skin-side sheet were clearly in focus, and an average thereof was calculated as “contact angle”.

[0056]

In order to facilitate the reliable shift of wearer’s sweat to the non-skin-side sheet 5, the non-skin-side sheet 5 has a basis weight that is preferably 10 g/m² or greater, and more preferably 20 g/m² or greater, is preferably 50 g/m² or less, and more preferably 30 g/m² or less, and, specifically, is preferably from 10 to 50 g/m², and more preferably from 20 to 30 g/m².

From the same point of view, the non-skin-side sheet 5 is such that portions thereof other than the joined regions 8 have a thickness that is preferably 100 pm or greater, and more preferably 150 pm or greater, is preferably 800 pm or less, and more preferably 500 pm or less, and, specifically, is preferably from 100 to 800 pm, and more preferably from 150 to 500 pm. The thickness of the non-skin-side sheet 5 is measured using a thickness gauge in a state where 0.05 kPa of pressure is applied to the non-skin-side sheet 5. A laser displacement gauge manufactured by Omron Corporation is used as a thickness gauge. The thickness is measured at ten points, and an average thereof is calculated as the thickness.

[0057]

In order to facilitate the reliable shift of wearer’s sweat to the non-skin-side sheet 5, the non-skin-side sheet 5 has a hydrophilic fiber content with respect to all constituent fibers of preferably 80% by mass or greater, and more preferably 90% by mass or greater, and the lower limit thereof is preferably 70% by mass.

[0058]

Furthermore, in order to facilitate the reliable shift of wearer’s sweat to the non-skin-side sheet 5, the non-skin-side sheet 5 has a Klemm water absorption height at 30 mm width, as measured according to JIS P 8141, of preferably 20 mm or greater at 60 seconds, and more preferably 25 mm or greater at 60 seconds. There is no particular limitation on the upper limit of the Klemm water absorption height of the non-skin-side sheet 5, but sufficiently satisfactory results are obtained if it is 30 mm at 60 seconds.

The Klemm water absorption height of the non-skin-side sheet 5 is measured using the following method.

[0059]

Method for Measuring Klemm Water Absorption Height

When taking the non-skin-side sheet 5 out of the outer cover of the pull-on disposable diaper, if the skin-side sheets 4, the non-skin-side sheet 5, and the outer sheet 6 are fusion bonded or fixed via an adhesive to each other, the fixed portions are eliminated through melting or the like using a solvent or hot air from a drier or the like, and thus the non-skin-side sheet 5 is taken out. The taken out non-skin-side sheet 5 is taken as a sample, and the Klemm water absorption height thereof is measured according to the test method as defined in JIS P 8141. Specifically, the taken out non-skin-side sheet 5 is cut into a portion with a width (the length in the longitudinal direction (X direction) of the diaper 1) of 30 mm and a length (the length in the lateral direction (Y direction) of the diaper 1) of 150 mm. When performing the cutting, cutting methods with which a sample may collapse due to pressure, such as those using a pushing cutter, are not preferable because the results may be severely affected. Thus, when performing the cutting, the sample is cut using a knife, a cutter, a razor, or the like such that the cut face thereof does not collapse. Next, the cut sample is set on a jig as defined in JIS P 8141, the Klemm water absorption height after 60 seconds is measured using water as a test liquid. The test liquid may be colored as appropriate using a dye such as Blue No. 1 or methylene blue such that the absorption height can be easily seen. This measurement is performed five times, and an average thereof is calculated as the Klemm water absorption height of the non-skin-side sheet 5. Note that the measurement environment temperature is set to 22°C.

[0060]

Furthermore, in order to facilitate the reliable shift of wearer’s sweat to the non-skin-side sheet 5, the non-skin-side sheet 5 has a saturated water-absorption amount of deionized water of preferably 75 g/m² or greater, and more preferably 100 g/m² or greater. There is no particular limitation on the upper limit of the saturated water-absorption amount of the non-skin-side sheet 5, but sufficiently satisfactory results are obtained if it is 300 g/m².

The saturated water-absorption amount of the non-skin-side sheet 5 is measured using the following method.

[0061]

Method for Measuring Saturated Water-Ab sorption Amount

A measurement sample is produced by cutting the non-skin-side sheet into a portion with a width of 50 mm and a length of 50 mm. The measurement sample is immersed in deionized water whose temperature is adjusted to 25°C. The sample is taken out of the deionized water five minutes after the immersion is started, and is then drained by being vertically suspended for 30 seconds. The mass of the sample that has absorbed water is measured, and the targeted saturated water-absorption amount is calculated using the following formula. The calculation is performed as follows: Saturated water-absorption amount (g/m²) = (sample mass (g) after water absorption sample mass (g) before water absorption) / (measurement sample area 0.05 m x 0.05 m). This measurement is performed five times, and an average thereof is calculated as the saturated water-absorption amount of the non-skin-side sheet.

[0062]

Although the present invention has been described above, the present invention is not limited to the foregoing embodiment, and changes can be made thereto as appropriate.

For example, the above-described diaper 1 is such that the skin-side sheets 4 forming the outer cover 3 are formed of the folded-back portions 6R of one outer sheet 6 as shown in FIG. 2, but may be hydrophobic sheets (nonwoven fabrics) that are separate from the outer sheet 6. If such skin-side sheets 4 are arranged as separate members, it is sufficient that at least the rear waist flap FB of the front waist flap FA and the rear waist flap FB is provided with such a skin-side sheet 4 as a separate member.

[0063]

Furthermore, as shown in FIG. 3, in the diaper 1, the number of hydrophilic non-skin-side sheets 5 provided at least in the rear waist flap FB is one, but may be two or more. If the number of hydrophilic non-skin-side sheets 5 is two or more in this manner, their hydrophilicity preferably increases in accordance with an increase in the distance from the wearer’s skin. That is to say, in comparison with a non-skin-side sheet that is adjacent to the skin-side sheet 4, at least any one of the above-described hydrophilic fiber content with respect to all constituent fibers, the above-described basis weight of the non-skin-side sheet, the above-described Klemm water absorption height, and the above-described saturated water-absorption amount is preferably larger than that of the non-skin-side sheet that is adjacent to the skin-side sheet 4, in accordance with an increase in the distance from the skin-side sheet 4.

[0064]

Furthermore, as shown in FIG. 2, in the outer cover 3 of the diaper 1, the outer sheet 6 and the non-skin-side sheet 5 joined and fixed to each other via the plurality of joined regions 8 through fusion bonding, and the skin-side sheets 4 and the non-skin-side sheet 5 are fixed to each other via the adhesive 9, but the adhesive 9 may not be provided. Furthermore, as shown in FIG. 2, in the outer cover 3 of the diaper 1, the elastic members 71 are arranged between the outer sheet 6 and the non-skin-side sheet 5, but the elastic members 71 may not be provided therebetween.

[0065]

Furthermore, as shown in FIG. 2, the above-described disposable diaper 1 is a pull-on disposable diaper in which the outer cover 3 is in the shape of an hourglass or the like continuously extending from the front region A via the crotch region C to the rear region B, but may be a pull-on disposable diaper in which the outer cover 3 is of a separate type and is divided into separate members composed of a front outer cover, a rear outer cover, and a crotch outer cover.

[0066]

Furthermore, as shown in FIG. 1, the above-described disposable diaper 1 is a pull-on disposable diaper having the outer cover 3, but may be an open type disposable diaper. In the case of an open type disposable diaper including a liquid permeable topsheet, a sparingly liquid permeable backsheet, and an absorbent member between these sheets, the topsheet corresponds to the non-skin-side sheet 5. It is sufficient that at least the rear waist flap FB of the front waist flap FA and the rear waist flap FB extending in the lateral direction Y and positioned outward of the front and rear ends, respectively, in the longitudinal direction X of the absorbent member is provided with a hydrophobic skin-side sheet 4 as a separate member that forms the skin-contacting surface.

[0067]

With regard to the foregoing embodiments, the following disposable diapers will be further disclosed.

[0068] < 1 > A disposable diaper comprising, in a longitudinal direction, a front region, a rear region, and a crotch region positioned between the front region and the rear region, having an absorbent member spanning from the front region to the rear region, and having a front waist flap and a rear waist flap extending in a lateral direction and positioned outward of front and rear end portions, respectively, in the longitudinal direction of the absorbent member, wherein at least the rear waist flap has a hydrophobic skin-side sheet that forms a skin-contacting surface, and a hydrophilic non-skin-side sheet that is positioned on a non-skin-facing surface side of the skin-side sheet, the skin-side sheet includes a plurality of depressed portions depressed toward the non-skin-side sheet, and bonded portions at top sections in the respective depressed portions, the bonded portions include portions in which constituent fibers of the skin-side sheet are melted and bonded to each other with no gap therebetween, a basis weight of the skin-side sheet is 30 g/m² or less, and a thickness of the bonded portions in the depressed portions is 1/3 or less of a thickness of portions other than the depressed portions in the skin-side sheet.

<2> The disposable diaper as set forth in clause 1, wherein the bonded portions are such that the portions in which constituent fibers of the skin-side sheet are melted and bonded to each other with no gap therebetween are made into a film.

< 3 > The disposable diaper as set forth in clause 1 or 2, wherein a perimeter length of each of the bonded portions is from 2 to 20 mm.

<4> The disposable diaper as set forth in any one of clauses 1 to 3, wherein the thickness of the bonded portions is 60 pm or less.

<5> The disposable diaper as set forth in any one of clauses 1 to 4, wherein the thickness of the portions other than the depressed portions in the skin-side sheet is 600 pm or less.

<6> The disposable diaper as set forth in any one of clauses 1 to 5, wherein an outer periphery of each bonded portion in the depressed portions has a thickness that gradually becomes thinner toward the bonded portion.

<7> The disposable diaper as set forth in any one of clauses 1 to 6, wherein a contact angle between the skin-side sheet forming an outer periphery of each bonded portion in the depressed portions and deionized water is smaller on the bonded portion side in the outer periphery than on the outer edge side of the depressed portion in the outer periphery. <8> The disposable diaper as set forth in any one of clauses 1 to 7, wherein the disposable diaper includes a hydrophobic outer sheet on the non-skin-facing surface side of the non-skin-side sheet, and includes a gather portion in which the skin-side sheet alternately forms projections projecting toward the skin side and depressions depressed toward the non-skin side along the width direction of the disposable diaper due to contraction of a plurality of elastic members arranged in a state of being stretched in the lateral direction of the disposable diaper between the non-skin-side sheet and the outer sheet, and the elastic members are intermittently arranged along the longitudinal direction of the disposable diaper, and in a cross-section of the gather portion, 60% or greater of all of the bonded portions are arranged from a position that is at half a depth of the depressions depressed toward the non-skin side of the skin-side sheet to the projection side projecting toward the skin side.

<9> The disposable diaper as set forth in any one of clauses 1 to 8, wherein the hydrophilic non-skin-side sheet has a hydrophilic fiber content with respect to all constituent fibers of 80% by mass or greater, and a basis weight of 10 g/m² or greater. <10> The disposable diaper as set forth in any one of clauses 1 to 9, wherein the skin-side sheet and the non-skin-side sheet are bonded to each other via an adhesive, and the portion in which the adhesive is arranged overlaps some of the bonded portions of the skin-side sheet.

<11> The disposable diaper as set forth in any one of clauses 1 to 10, wherein the disposable diaper includes a hydrophobic outer sheet on the non-skin-facing surface side of the non-skin-side sheet, and a plurality of elastic members arranged in a state of being stretched in the lateral direction of the disposable diaper between the non-skin-side sheet and the outer sheet, and the elastic members are intermittently arranged along the longitudinal direction of the disposable diaper, and the elastic members overlap some of the bonded portions of the skin-side sheet.

<12> The disposable diaper as set forth in any one of clauses 1 to 11, wherein the skin-side sheet 4 has a basis weight that is 30 g/m² or less, preferably 20 g/m² or less, and a lower limit thereof is preferably 9 g/m², more preferably 10 g/m².

<13> The disposable diaper as set forth in any one of clauses 1 to 12, wherein a thickness dl of the bonded portions in the depressed portions forming the skin-side sheet is 1/3 or less, preferably 1/4 or less, more preferably 1/5 or less, of a thickness d2 of portions other than the depressed portions in the skin-side sheet, and a lower limit thereof is 1/30.

<14> The disposable diaper as set forth in any one of clauses 1 to 13, wherein a thickness dl of the bonded portions is preferably 60 μιη or less, more preferably 45 μηι or less, and a lower limit thereof is 10 μιη.

<15> The disposable diaper as set forth in any one of clauses 1 to 14, wherein a thickness d2 of portions other than the depressed portions in the skin-side sheet is preferably 600 μιη or less, more preferably 350 μιη, and a lower limit thereof is 100 μιη.

< 16> The disposable diaper as set forth in any one of clauses 1 to 15, wherein the outer periphery is formed in the shape of a ring along the outer periphery of the bonded portion in the depressed portion, and the ring-shaped outer periphery has a thickness that is thinner on the inner side located closer to the bonded portion than on the outer side and that gradually becomes thinner from the outer side toward the inner side located closer to the bonded portion.

< 17> The disposable diaper as set forth in any one of clauses 1 to 16, wherein, when a depth of the depressed portion at each bonded portion is taken as d3, a thickness at a position that is distanced outward from an end of the bonded portion by a distance that is 0.50 times the depth d3 is preferably from 20 to 75%, more preferably from 70 to 90%, of a thickness d2 of portions other than the depressed portion.

< 18> The disposable diaper as set forth in any one of clauses 1 to 17, wherein, when a depth of the depressed portion at each bonded portion is taken as d3, a thickness at a position that is distanced outward from a center of the bonded portion by a distance that is

1.5 times the depth d3 is preferably from 55 to 95%, more preferably from 70 to 90%, of a thickness d2 of portions other than the depressed portion.

< 19> The disposable diaper as set forth in any one of clauses 1 to 18, further including a gather portion in which the skin-side sheet alternately forms projections projecting toward the skin side and depressions depressed toward the non-skin side along the width direction of the disposable diaper due to contraction of a plurality of elastic members arranged in a state of being stretched in the lateral direction of the disposable diaper between the non-skin-side sheet and a hydrophobic outer sheet on the non-skin-facing surface side of the non-skin-side sheet, and the elastic members are intermittently arranged along the longitudinal direction of the disposable diaper, and in a cross-section of the gather portion formed through contraction of the elastic members, preferably 60% or greater, more preferably 75% or greater ,of all of the bonded portions are arranged from a position that is at half a depth of the depressions depressed toward the non-skin side of the skin-side sheet to the projection side, and a upper limit thereof is preferably 100%.

<20> The disposable diaper as set forth in any one of clauses 1 to 19, wherein, in an outer periphery of each bonded portion in the depressed portions, the skin-side sheet forming the bonded portion side has a contact angle with respect to deionized water that is preferably 120° or less, more preferably 110° or less, and a lower limit thereof is 90°.

<21 > The disposable diaper as set forth in any one of clauses 1 to 20, wherein, in an outer periphery of each bonded portion in the depressed portions, the skin-side sheet forming the outer edge side of the depressed portion has a contact angle with respect to deionized water that is preferably 120° or greater, more preferably 130° or greater, and a upper limit thereof is 180°.

<22> The disposable diaper as set forth in any one of clauses 1 to 21, wherein a difference between a contact angle between the skin-side sheet forming the bonded portion side in an outer periphery and deionized water and a contact angle between the skin-side sheet forming the outer edge side of the depressed portion in the outer periphery and deionized water is preferably 15° or greater, more preferably 25° or greater.

<23> The disposable diaper as set forth in any one of clauses 1 to 22, wherein the bonded portions are arranged on the skin-side sheet preferably at least outward in the longitudinal direction of an edge of a rear end (on the side opposite to the lateral center line CL2) in the longitudinal direction of the absorbent member forming an absorbent assembly, and are intermittently arranged throughout the skin-side sheet in the disposal diaper.

<24> The disposable diaper as set forth in any one of clauses 1 to 23, wherein the bonded portions are intermittently arranged in a row along the longitudinal direction, and a plurality of bonded portion rows formed of the plurality of bonded portions are arranged at intervals along the lateral direction.

<25> The disposable diaper as set forth in any one of clauses 1 to 24, wherein the bonded portions are intermittently arranged in a row along the longitudinal direction, and bonded portion rows formed of the plurality of bonded portions and joined region rows formed of the plurality of joined regions that join the non-skin-side sheet and the outer sheet are alternately arranged in the lateral direction.

<26> The disposable diaper as set forth in any one of clauses 1 to 25, wherein an interval between the bonded portions that are adjacent to each other in the longitudinal direction and that form the bonded portion rows extending in the longitudinal direction is preferably 1 mm or greater, more preferably 3 mm or greater, is preferably 20 mm or less, more preferably 18 mm or less.

<27> The disposable diaper as set forth in any one of clauses 1 to 26, wherein an interval between the bonded portion rows that are adjacent to each other in the lateral direction is preferably 4 mm or greater, more preferably 6 mm or greater, is preferably 20 mm or less, more preferably 16 mm or less.

<28> The disposable diaper as set forth in any one of clauses 1 to 27, wherein each of the bonded portions has an area that is preferably 0.5 mm² or greater, more preferably 0.75 mm² or greater, is preferably 5 mm² or less, more preferably 4 mm² or less.

<29> The disposable diaper as set forth in any one of clauses 1 to 28, wherein each of the bonded portions has a perimeter length that is preferably 2 mm or greater, more preferably 3 mm or greater, is preferably 20 mm or less, more preferably 15 mm or less. <30> The disposable diaper as set forth in any one of clauses 1 to 29, wherein, in plan view of the rear waist flap in its flat-out, uncontracted state, a proportion of an area of all bonded portions with respect to a total area of the skin-side sheet is preferably 1% or greater, more preferably 3% or greater, is preferably 15% or less, more preferably 10% or less.

<31> The disposable diaper as set forth in any one of clauses 1 to 30, wherein the non-skin-side sheet has a basis weight that is preferably 10 g/m² or greater, 20 g/m² or greater, is preferably 50 g/m² or less, more preferably 30 g/m² or less.

<32> The disposable diaper as set forth in any one of clauses 1 to 31, wherein a thickness of portions other than joined regions that join the non-skin-side sheet and a hydrophobic outer sheet on the non-skin-facing surface side of the non-skin-side sheet in the non-skin-side sheet is preferably 100 pm or greater, more preferably 150 pm or greater, is preferably 800 pm or less, more preferably 500 pm or less.

<33 > The disposable diaper as set forth in any one of clauses 1 to 32, wherein the non-skin-side sheet has a hydrophilic fiber content with respect to all constituent fibers of preferably 80% by mass or greater, and more preferably 90% by mass or greater.

<34> The disposable diaper as set forth in any one of clauses 1 to 33, wherein the non-skin-side sheet has a Klemm water absorption height at 30 mm width, as measured according to JIS P 8141, of preferably 20 mm or greater at 60 seconds, more preferably mm or greater at 60 seconds, and there is no particular limitation on the upper limit of the Klemm water absorption height of the non-skin-side sheet 5, but preferably 30 mm at 60 seconds.

<35> The disposable diaper as set forth in any one of clauses 1 to 34, wherein the non-skin-side sheet has a saturated water-absorption amount of deionized water of preferably 75 g/m² or greater, and more preferably 100 g/m² or greater, and there is no particular limitation on the upper limit of the saturated water-absorption amount of the non-skin-side sheet, but preferably 300 g/m².

<36> The disposable diaper as set forth in any one of clauses 1 to 35, including the skin-side sheet and the non-skin-side sheet, and further including a hydrophobic outer sheet on the non-skin-facing surface side of the non-skin-side sheet.

<37> The disposable diaper as set forth in any one of clauses 1 to 36, wherein the disposable diaper includes a hydrophobic outer sheet on the non-skin-facing surface side of the non-skin-side sheet, and the skin-side sheet is formed of a folded-back portion of the outer sheet.

<38> The disposable diaper as set forth in any one of clauses 1 to 37, wherein joined regions that join the non-skin-side sheet and the outer sheet are intermittently arranged in a row along the longitudinal direction in a region spanning from a waist elasticized portion to a below-waist lower elasticized portion of each of the front region and the rear region, and a plurality of joined region rows formed of the plurality of joined regions are arranged at intervals along the lateral direction.

<39> The disposable diaper as set forth in any one of clauses 1 to 38, wherein joined regions that join the non-skin-side sheet and a hydrophobic outer sheet on the non-skin-facing surface side of the non-skin-side sheet are intermittently arranged in a row along the longitudinal direction, and an interval between the joined regions that are adjacent to each other in the longitudinal direction and that form the joined region rows extending in the longitudinal direction is preferably 1 mm or greater, more preferably 3 mm or greater, is preferably 20 mm or less, more preferably 18 mm or less.

<40> The disposable diaper as set forth in any one of clauses 1 to 39, wherein joined regions that join the non-skin-side sheet and a hydrophobic outer sheet on the non-skin-facing surface side of the non-skin-side sheet are intermittently arranged in a row along the longitudinal direction, and an interval between the joined region rows that are adjacent to each other in the lateral direction is preferably 4 mm or greater, more preferably 6 mm or greater, is preferably 20 mm or less, more preferably 16 mm or less.

<41 > The disposable diaper as set forth in any one of clauses 1 to 40, wherein, in a case where a plurality of the hydrophilic non-skin-side sheets are provided, hydrophilicity preferably increases in accordance with an increase in a distance from the wearer’s skin. <42> The disposable diaper as set forth in any one of clauses 1 to 41, wherein, in comparison with the non-skin-side sheet that is adjacent to the skin-side sheet, at least any one of a hydrophilic fiber content with respect to all constituent fibers, a basis weight of the non-skin-side sheet, a Klemm water absorption height, and a saturated water-absorption amount is preferably larger than that of the non-skin-side sheet that is adjacent to the skin-side sheet, in accordance with an increase in a distance from the skin-side sheet.

Examples [0069]

Hereinafter, the absorbent article of the present invention will be described in more detail by way of examples. However, the scope of the present invention is not limited to these examples.

[0070]

Example 1 (1) Preparation of Skin-Side Sheet

As a nonwoven fabric for the skin-side sheet, a rectangular hydrophobic spunbonded nonwoven fabric with a length in the MD direction of 50 mm and a length in the CD direction of 50 mm was prepared. The nonwoven fabric for the skin-side sheet was made of hydrophobic polypropylene (PP) fibers with a melting point of 160°C.

Furthermore, the nonwoven fabric for the skin-side sheet had a basis weight of 17 g/m². The nonwoven fabric for the skin-side sheet was subjected to heat embossing using an embossment apparatus heated to 200°C, so that a skin-side sheet was produced having bonded portions that each had an area of 1.3 mm² and a perimeter length of 4 mm, and were arranged adjacent to each other in the MD direction at intervals of 3 mm and adjacent to each other in the CD direction at intervals of 4 mm. The thus formed bonded portions contained film-like portions in which fibers were melted and bonded to each other with no gap therebetween. Furthermore, regarding the nonwoven fabric for the skin-side sheet, the thickness dl (see FIG. 3) of the bonded portions measured according to the above-described measuring method was 50 pm, the thickness d2 (see FIG. 3) of portions other than the depressed portions was 220 pm, and the proportion of the thickness dl of the bonded portions with respect to the thickness d2 of the portions other than the depressed portions was 5/22. Furthermore, the contact angle between portions near the bonded portions in the outer peripheries and deionized water measured according to the above-described “Method for Measuring Contact Angle of Skin-Side Sheet” was 108°, the contact angle between portions near outer edges of the depressed portions in the outer peripheries and deionized water was 135°, and the difference between the contact angles was 27°.

(2) Preparation of Non-Skin-Side Sheet

As a nonwoven fabric for the non-skin-side sheet, a hydrophilic spunbonded nonwoven fabric with the same shape and the same size as the nonwoven fabric for the skin-side sheet was prepared. The nonwoven fabric for the non-skin-side sheet was formed by applying a hydrophilic oil agent to a spunbonded nonwoven fabric made of hydrophobic polypropylene (PP) fibers.

(3) Production of Fayered Sheet in Example 1

A hot melt adhesive was applied at a basis weight of 6 g/m² in the form of a spiral to a face of the above-described skin-side sheet opposite to the face on which the bonded portions were formed, and then the above-described non-skin-side sheet was arranged, so that a layered sheet of Example 1 in which the skin-side sheet and the non-skin-side sheet were fixed was produced.

[0071]

Example 2 (1) Preparation of Skin-Side Sheet

As a nonwoven fabric for the skin-side sheet, a hydrophobic spunbonded nonwoven fabric with a basis weight of 10 g/m² was prepared. The nonwoven fabric for the skin-side sheet was subjected to heat embossing as in Example 1. The thus formed bonded portions contained portions in which fibers were melted and bonded to each other had no gap therebetween, but were not made into a film. Regarding the nonwoven fabric for the skin-side sheet, the thickness dl (see FIG. 3) of the bonded portions measured according to the above-described measuring method was 65 pm, the thickness d2 (see FIG. 3) of portions other than the depressed portions was 200 pm, and the proportion of the thickness dl of the bonded portions with respect to the thickness d2 of the portions other than the depressed portions was 13/40. Furthermore, the contact angle between portions near the bonded portions in the outer peripheries and deionized water measured according to the above-described “Method for Measuring Contact Angle of Skin-Side Sheet” was 114°, the contact angle between portions near outer edges of the depressed portions in the outer peripheries and deionized water was 130°, and the difference between the contact angles was 16°.

(2) Preparation of Non-Skin-Side Sheet

As a nonwoven fabric for the skin-side sheet, a hydrophilic spunbonded nonwoven fabric similar to the non-skin-side sheet of Example 1 was prepared.

(3) Production of Eayered Sheet in Example 2

A hot melt adhesive was applied to the above-described skin-side sheet as in Example 1, and then the above-described non-skin-side sheet was arranged, so that a layered sheet of Example 2 in which the skin-side sheet and the non-skin-side sheet were fixed was produced.

[0072]

Example 3 (1) Preparation of Skin-Side Sheet

As a nonwoven fabric for the skin-side sheet, a hydrophobic air-through nonwoven fabric was prepared. The nonwoven fabric for the skin-side sheet was made of a composite fiber containing polyethylene (PE) fibers with a melting point of 125°C and polyethylene terephthalate (PET) fibers with a melting point of 250°C. Furthermore, the nonwoven fabric for the skin-side sheet had a basis weight of 20 g/m². The nonwoven fabric for the skin-side sheet was subjected to heat embossing using an embossment apparatus heated to 200°C, so that a skin-side sheet was produced having bonded portions that each had an area of 375 mm² and a perimeter length of 115 mm, and were arranged adjacent to each other in the MD direction at intervals of 10 mm and adjacent to each other in the CD direction at intervals of 10 mm. The thus formed bonded portions contained film-like portions in which fibers were melted and bonded to each other with no gap therebetween. Furthermore, regarding the nonwoven fabric for the skin-side sheet, the thickness dl (see FIG. 3) of the bonded portions measured according to the above-described measuring method was 60 pm, the thickness d2 (see FIG. 3) of portions other than the depressed portions was 450 pm, and the proportion of the thickness dl of the bonded portions with respect to the thickness d2 of the portions other than the depressed portions was 2/15. Furthermore, the contact angle between portions near the bonded portions in the outer peripheries and deionized water measured according to the above-described “Method for Measuring Contact Angle of Skin-Side Sheet” was 98°, the contact angle between portions near outer edges of the depressed portions in the outer peripheries and deionized water was 120°, and the difference between the contact angles was 22°.

(2) Preparation of Non-Skin-Side Sheet

(3) Production of Fayered Sheet in Example 3

A hot melt adhesive was applied to the above-described skin-side sheet as in

Example 1, and then the above-described non-skin-side sheet was arranged, so that a layered sheet of Example 3 in which the skin-side sheet and the non-skin-side sheet were fixed was produced.

[0073]

Example 4 (1) Preparation of Skin-Side Sheet

As a nonwoven fabric for the skin-side sheet, a hydrophobic spunbonded nonwoven fabric with a basis weight of 13 g/m² was prepared. The nonwoven fabric for the skin-side sheet was subjected to heat embossing as in Example 1. The thus formed bonded portions contained portions in which fibers were melted and bonded to each other with no gap therebetween, but were not made into a film. Regarding the nonwoven fabric for the skin-side sheet, the thickness dl (see FIG. 3) of the bonded portions measured according to the above-described measuring method was 70 pm, the thickness d2 (see FIG. 3) of portions other than the depressed portions was 220 pm, and the proportion of the thickness dl of the bonded portions with respect to the thickness d2 of the portions other than the depressed portions was 7/22. Furthermore, the contact angle between portions near the bonded portions in the outer peripheries and deionized water measured according to the above-described “Method for Measuring Contact Angle of Skin-Side Sheet” was 117°, the contact angle between portions near outer edges of the depressed portions in the outer peripheries and deionized water was 138°, and the difference between the contact angles was 21°.

(2) Preparation of Non-Skin-Side Sheet

(3) Production of Fayered Sheet in Example 4

A hot melt adhesive was applied to the above-described skin-side sheet as in Example 1, and then the above-described non-skin-side sheet was arranged, so that a layered sheet of Example 4 in which the skin-side sheet and the non-skin-side sheet were fixed was produced.

[0074]

Comparative Example 1 (1) Preparation of Skin-Side Sheet

As a nonwoven fabric for the skin-side sheet, a hydrophobic spunbonded nonwoven fabric as in Example 1 was prepared. The nonwoven fabric for the skin-side sheet was not subjected to heat embossing.

(2) Preparation of Non-Skin-Side Sheet

As a nonwoven fabric for the non-skin-side sheet, a hydrophobic spunbonded nonwoven fabric similar to the nonwoven fabric for the skin-side sheet was prepared.

(3) Production of Tayered Sheet in Comparative Example 1

A hot melt adhesive was applied to the above-described skin-side sheet as in Example 1, and then the above-described non-skin-side sheet was arranged, so that a layered sheet of Comparative Example 1 in which the skin-side sheet and the non-skin-side sheet were fixed was produced.

[0075]

Comparative Example 2 (1) Preparation of Skin-Side Sheet

As a nonwoven fabric for the skin-side sheet, a hydrophobic spunbonded nonwoven fabric as in Example 1 was prepared. The nonwoven fabric for the skin-side sheet was subjected to heat embossing using an embossment apparatus heated to 30°C, which is lower than the melting point of the constituent fibers, so that a skin-side sheet was produced having bonded portions that each had an area of 1.3 mm² and a perimeter length of 4 mm, and were arranged adjacent to each other in the MD direction at intervals of 3 mm and adjacent to each other in the CD direction at intervals of 4 mm. In the thus formed bonded portions, the constituent fibers did not lose their fiber form. Furthermore, regarding the nonwoven fabric for the skin-side sheet, the thickness of the bonded portions measured according to the above-described measuring method was 150 pm, the thickness of portions other than the depressed portions was 250 pm, and the proportion of the thickness of the bonded portions with respect to the thickness of the portions other than the depressed portions was 3/5.

(2) Preparation of Non-Skin-Side Sheet

As a nonwoven fabric for the non-skin-side sheet, a hydrophilic spunbonded nonwoven fabric as in Example 1 was prepared.

(3) Production of Layered Sheet in Comparative Example 2

A hot melt adhesive was applied to the above-described skin-side sheet as in Example 1, and then the above-described non-skin-side sheet was arranged, so that a layered sheet of Comparative Example 2 in which the skin-side sheet and the non-skin-side sheet were fixed was produced.

[0076]

Comparative Example 3 (1) Preparation of Skin-Side Sheet

As a nonwoven fabric for the skin-side sheet, a hydrophobic spunbonded nonwoven fabric with a basis weight of 8 g/m² was prepared. The nonwoven fabric for the skin-side sheet was subjected to heat embossing as in Example E Regarding the nonwoven fabric for the skin-side sheet, the thickness dl (see FIG. 3) of the bonded portions measured according to the above-described measuring method was 55 pm, the thickness d2 (see FIG. 3) of portions other than the depressed portions was 140 pm, and the proportion of the thickness dl of the bonded portions with respect to the thickness d2 of the portions other than the depressed portions was 11/28.

(2) Preparation of Non-Skin-Side Sheet

(3) Production of Layered Sheet in Comparative Example 3

A hot melt adhesive was applied to the above-described skin-side sheet as in Example 1, and then the above-described non-skin-side sheet was arranged, so that a layered sheet of Comparative Example 3 in which the skin-side sheet and the non-skin-side sheet were fixed was produced.

[0077]

Comparative Example 4 (1) Preparation of Skin-Side Sheet

(2) Preparation of Non-Skin-Side Sheet

As a nonwoven fabric for the non-skin-side sheet, a hydrophobic spunbonded nonwoven fabric similar to the skin-side sheet and the non-skin-side sheet of Comparative Example 1 was prepared.

(3) Production of Layered Sheet in Comparative Example 4

A hot melt adhesive was applied to the above-described skin-side sheet as in Example 1, and then the above-described non-skin-side sheet was arranged, so that a layered sheet of Comparative Example 4 in which the skin-side sheet and the non-skin-side sheet were fixed was produced.

[0078]

Performance Evaluation

Regarding the layered sheets of Examples 1 to 4 and Comparative Examples 1 to 4, the amount of fluid remaining on the skin was measured, and sensory evaluation of a dry feel on the skin was performed, using the following methods. Table 1 below shows the results.

[0079]

Method for Measuring Amount of Fluid Remaining on the Skin mg of deionized water was dropped onto a horizontally placed glass plate with a smooth surface. A layered sheet was placed thereon such that its skin-side sheet faced the plate. After maintaining this state for one minute, the layered sheet was removed, and the amount of deionized water remaining on the plate was measured. The measurement was performed three times, and an average thereof was calculated as the amount of fluid remaining on skin. The measurement was performed at a room temperature of 23°C and a relative humidity of 50%.

Evaluation Criteria

A: Amount of fluid remaining on the skin is less than 1 mg.

B: Amount of fluid remaining on the skin is 1 mg or greater and less than 10 mg.

C: Amount of fluid remaining on the skin is 10 mg or greater and less than 20 mg.

D: Amount of fluid remaining on the skin is 20 mg or greater and less than 45 mg.

E: Amount of fluid remaining on the skin is 45 mg or greater.

[0080]

Sensory Evaluation Method for Dry feel on the skin pL of physiological saline solution (0.9% by mass of aqueous sodium chloride) was dropped onto five points of a forearm of each of five healthy adults. A layered sheet was placed thereon such that its skin-side sheet faced the forearm. After maintaining this state for 10 minutes, the layered sheet was removed, and the dry feel on the skin immediately after the removal was subjected to sensory evaluation following the criteria below.

Evaluation Criteria points: Skin is dry.

points: Skin is relatively dry.

points: Skin is moist.

points: Skin is sticky.

point: Fluid remains on the skin.

The average points of the five people were evaluated following the criteria below. Table 1 shows the results. The evaluation was performed at a room temperature of 23°C and a relative humidity of 50%.

Evaluation Criteria

A: 4.5 or greater

B: 3.5 or greater and less than 4.5

C: 2.5 or greater and less than 3.5

D: 1.5 or greater and less than 2.5

E: less than 1.5 [0081]

Table 1

	Ex. 1	Ex. 2	Ex. 3	Ex. 4	Com. Ex. 1	Com. Ex. 2	Com. Ex. 3	Com. Ex. 4
Amount of fluid remaining on skin	A	C	B	B	E	D	C	B
Dry feel on skin	A	B	B	B	E	E	D	C

[0082]

It is seen from the results in Table 1 that, according to a comparison between Examples 1 to 4 using a hydrophobic skin-side sheet and Comparative Examples 1 to 3, the layered sheets of Examples 1 to 4 left a smaller amount of fluid remaining on the skin and provided a better dry feel on the skin compared with the layered sheets of Comparative Examples 1 to 3. Furthermore, in Comparative Example 4 using a hydrophilic skin-side sheet, although the amount of fluid remaining on the skin was small, the sheet that had absorbed liquid came into direct contact with the skin because the skin-side sheet was hydrophilic, and thus the dry feel on the skin was poor. Accordingly, if a pull-on disposable diaper is produced using the nonwoven fabric for the skin-side sheet and the nonwoven fabric for the non-skin-side sheet used for the layered sheets of Examples 1 to 4 respectively as the skin-side sheets 4 and the non-skin-side sheet 5, it is expected that the wearer’s sweat can be quickly shifted to the non-skin-facing surface side, that the dry feel on the skin can be improved, and that skin issues such as eczema, heat rashes, and rashes can be reduced.

Industrial Applicability [0083]

According to the present invention, sweat that has been absorbed can be quickly shifted to the non-skin-facing surface side, and thus it is expected that the dry feel on the skin can be improved, and that skin issues such as eczema, heat rashes, and rashes can be reduced.

Claims

CLAIMS [Claim 1] A disposable diaper comprising, in a longitudinal direction, a front region, a rear region, and a crotch region positioned between the front region and the rear region, having an absorbent member spanning from the front region to the rear region, and having a front waist flap and a rear waist flap extending in a lateral direction and positioned outward of front and rear end portions, respectively, in the longitudinal direction of the absorbent member, wherein at least the rear waist flap has a hydrophobic skin-side sheet that forms a skin-contacting surface, and a hydrophilic non-skin-side sheet that is positioned on a non-skin-facing surface side of the skin-side sheet, the skin-side sheet includes a plurality of depressed portions depressed toward the non-skin-side sheet, and bonded portions at top sections in the respective depressed portions, the bonded portions include portions in which constituent fibers of the skin-side sheet are melted and bonded to each other with no gap therebetween, a basis weight of the skin-side sheet is 30 g/m² or less, and a thickness of the bonded portions in the depressed portions is 1/3 or less of a thickness of portions other than the depressed portions in the skin-side sheet.
[Claim 2] The disposable diaper according to claim 1, wherein the bonded portions are such that the portions in which constituent fibers of the skin-side sheet are melted and bonded to each other with no gap therebetween are made into a film.
[Claim 3] The disposable diaper according to claim 1 or 2, wherein a perimeter length of each of the bonded portions is from 2 to 20 mm.
[Claim 4] The disposable diaper according to any one of claims 1 to 3, wherein the thickness of the bonded portions is 60 pm or less.
[Claim 5] The disposable diaper according to any one of claims 1 to 4, wherein the thickness of the portions other than the depressed portions in the skin-side sheet is 600 pm or less.
[Claim 6] The disposable diaper according to any one of claims 1 to 5, wherein an outer periphery of each bonded portion in the depressed portions has a thickness that gradually becomes thinner toward the bonded portion.
[Claim 7] The disposable diaper according to any one of claims 1 to 6, wherein a contact angle between the skin-side sheet forming an outer periphery of each bonded portion in the depressed portions and deionized water is smaller on the bonded portion side in the outer periphery than on the outer edge side of the depressed portion in the outer periphery.
[Claim 8] The disposable diaper according to any one of claims 1 to 7, wherein the disposable diaper includes a hydrophobic outer sheet on the non-skin-facing surface side of the non-skin-side sheet, and includes a gather portion in which the skin-side sheet alternately forms projections projecting toward the skin side and depressions depressed toward the non-skin side along the width direction of the disposable diaper due to contraction of a plurality of elastic members arranged in a state of being stretched in the lateral direction of the disposable diaper between the non-skin-side sheet and the outer sheet, and the elastic members are intermittently arranged along the longitudinal direction of the disposable diaper, and in a cross-section of the gather portion, 60% or greater of all of the bonded portions are arranged from a position that is at half a depth of the depressions depressed toward the non-skin side of the skin-side sheet to the projection side projecting toward the skin side.
[Claim 9]

The disposable diaper according to any one of claims 1 to 8, wherein the hydrophilic non-skin-side sheet has a hydrophilic fiber content with respect to all constituent fibers of 80% by mass or greater, and a basis weight of 10 g/m² or greater.
[Claim 10] The disposable diaper according to any one of claims 1 to 9, wherein the skin-side sheet and the non-skin-side sheet are bonded to each other via an adhesive, and the portion in which the adhesive is arranged overlaps some of the bonded portions of the skin-side sheet.
[Claim 11] The disposable diaper according to any one of claims 1 to 10, wherein the disposable diaper includes a hydrophobic outer sheet on the non-skin-facing surface side of the non-skin-side sheet, and a plurality of elastic members arranged in a state of being stretched in the lateral direction of the disposable diaper between the non-skin-side sheet and the outer sheet, and the elastic members are intermittently arranged along the longitudinal direction of the disposable diaper, and the elastic members overlap some of the bonded portions of the skin-side sheet.
[Claim 12] The disposable diaper according to any one of claims 1 to 11, wherein the skin-side sheet has a basis weight that is from 9 to 30 g/m².
[Claim 13] The disposable diaper according to any one of claims 1 to 12, wherein a thickness dl of the bonded portions in the depressed portions forming the skin-side sheet is from 1/30 to 1/3 of a thickness d2 of portions other than the depressed portions in the skin-side sheet.
[Claim 14] The disposable diaper according to any one of claims 1 to 13, wherein a thickness dl of the bonded portions is from 10 to 60pm.
[Claim 15] The disposable diaper according to any one of claims 1 to 14, wherein a thickness d2 of portions other than the depressed portions in the skin-side sheet is from

100 to 600 μιη.
[Claim 16] The disposable diaper according to any one of claims 1 to 15, wherein an outer periphery of each bonded portion in the depressed portions is formed in the shape of a ring along the outer periphery of the bonded portion in the depressed portion, and the ring-shaped outer periphery has a thickness that is thinner on the inner side located closer to the bonded portion than on the outer side and that gradually becomes thinner from the outer side toward the inner side located closer to the bonded portion.
[Claim 17] The disposable diaper according to any one of claims 1 to 16, wherein, when a depth of the depressed portion at each bonded portion is taken as d3, a thickness at a position that is distanced outward from an end of the bonded portion by a distance that is 0.50 times the depth d3 is from 20 to 75% of a thickness d2 of portions other than the depressed portion.
[Claim 18] The disposable diaper according to any one of claims 1 to 17, wherein, when a depth of the depressed portion at each bonded portion is taken as d3, a thickness at a position that is distanced outward from a center of the bonded portion by a distance that is 1.5 times the depth d3 is from 55 to 95% of a thickness d2 of portions other than the depressed portion.
[Claim 19] The disposable diaper according to any one of claims 1 to 18, further including a gather portion in which the skin-side sheet alternately forms projections projecting toward the skin side and depressions depressed toward the non-skin side along the width direction of the disposable diaper due to contraction of a plurality of elastic members arranged in a state of being stretched in the lateral direction of the disposable diaper between the non-skin-side sheet and a hydrophobic outer sheet on the non-skin-facing surface side of the non-skin-side sheet, and the elastic members are intermittently arranged along the longitudinal direction of the disposable diaper, and in a cross-section of the gather portion formed through contraction of the elastic members, 60% to 100% of all of the bonded portions are arranged from a position that is at half a depth of the depressions depressed toward the non-skin side of the skin-side sheet, to the projection side.
[Claim 20] The disposable diaper according to any one of claims 1 to 19, wherein, in an outer periphery of each bonded portion in the depressed portions, the skin-side sheet forming the bonded portion side has a contact angle with respect to deionized water that is from 90° to 120°.
[Claim 21] The disposable diaper according to any one of claims 1 to 20, wherein, in an outer periphery of each bonded portion in the depressed portions, the skin-side sheet forming the outer edge side of the depressed portion has a contact angle with respect to deionized water that is from 120° to 180°.
[Claim 22] The disposable diaper according to any one of claims 1 to 21, wherein a difference between a contact angle between the skin-side sheet forming the bonded portion side in an outer periphery of each bonded portion in the depressed portions and deionized water and a contact angle between the skin-side sheet forming the outer edge side of the depressed portion in the outer periphery and deionized water is 15° or greater.
[Claim 23] The disposable diaper according to any one of claims 1 to 22, wherein the bonded portions are arranged on the skin-side sheet at least outward in the longitudinal direction of an edge of a rear end in the longitudinal direction of the absorbent member forming an absorbent assembly, and are intermittently arranged throughout the skin-side sheet.
[Claim 24] The disposable diaper according to any one of claims 1 to 23, wherein the bonded portions are intermittently arranged in a row along the longitudinal direction, and a plurality of bonded portion rows formed of the plurality of bonded portions are arranged at intervals along the lateral direction.
[Claim 25] The disposable diaper according to any one of claims 1 to 24, wherein the bonded portions are intermittently arranged in a row along the longitudinal direction, and bonded portion rows formed of the plurality of bonded portions and joined region rows formed of the plurality of joined regions that join the non-skin-side sheet and a hydrophobic outer sheet on the non-skin-facing surface side of the non-skin-side sheet are alternately arranged in the lateral direction.
[Claim 26] The disposable diaper according to any one of claims 1 to 25, wherein an interval between the bonded portions that are adjacent to each other in the longitudinal direction and that form the bonded portion rows extending in the longitudinal direction is from 1 to 20 mm.
[Claim 27] The disposable diaper according to any one of claims 1 to 26, wherein an interval between the bonded portion rows that are adjacent to each other in the lateral direction is from 4 to 20 mm.
[Claim 28] The disposable diaper according to any one of claims 1 to 27, wherein each of the bonded portions has an area that is from 0.5 to 5 mm².
[Claim 29] The disposable diaper according to any one of claims 1 to 28, wherein each of the bonded portions has a perimeter length that is from 2 to 20 mm.
[Claim 30] The disposable diaper according to any one of claims 1 to 29, wherein, in plan view of the rear waist flap in its flat-out, uncontracted state, a proportion of an area of all bonded portions with respect to a total area of the skin-side sheet is from 1 to 15%.
[Claim 31] The disposable diaper according to any one of claims 1 to 30, wherein the non-skin-side sheet has a basis weight that is from 10 to 50 g/m².
[Claim 32] The disposable diaper according to any one of claims 1 to 31, wherein a thickness of portions other than joined regions that join the non-skin-side sheet and a hydrophobic outer sheet on the non-skin-facing surface side of the non-skin-side sheet in the non-skin-side sheet is from 100 to 800 pm.
[Claim 33] The disposable diaper according to any one of claims 1 to 32, wherein the non-skin-side sheet has a hydrophilic fiber content with respect to all constituent fibers of 80% by mass or greater.
[Claim 34] The disposable diaper according to any one of claims 1 to 33, wherein the non-skin-side sheet has a Klemm water absorption height at 30 mm width, as measured according to JIS P 8141, of 20 mm or greater at 60 seconds.
[Claim 35] The disposable diaper according to any one of claims 1 to 34, wherein the non-skin-side sheet has a saturated water-absorption amount of deionized water of 75 g/m² or greater.
[Claim 36] The disposable diaper according to any one of claims 1 to 35, including the skin-side sheet and the non-skin-side sheet, and further including a hydrophobic outer sheet on the non-skin-facing surface side of the non-skin-side sheet.
[Claim 37] The disposable diaper according to any one of claims 1 to 36, wherein the disposable diaper includes a hydrophobic outer sheet on the non-skin-facing surface side of the non-skin-side sheet, and the skin-side sheet is formed of a folded-back portion of the outer sheet.
[Claim 38] The disposable diaper according to any one of claims 1 to 37, wherein joined regions that join the non-skin-side sheet and a hydrophobic outer sheet on the non-skin-facing surface side of the non-skin-side sheet are intermittently arranged in a row along the longitudinal direction in a region spanning from a waist elasticized portion to a below-waist lower elasticized portion of each of the front region and the rear region, and a plurality of joined region rows formed of the plurality of joined regions are arranged at intervals along the lateral direction.
[Claim 39] The disposable diaper according to any one of claims 1 to 38, wherein joined regions that join the non-skin-side sheet and a hydrophobic outer sheet on the non-skin-facing surface side of the non-skin-side sheet are intermittently arranged in a row along the longitudinal direction, and an interval between the joined regions that are adjacent to each other in the longitudinal direction and that form the joined region rows extending in the longitudinal direction is from 1 to 20 mm.
[Claim 40] The disposable diaper according to any one of claims 1 to 39, wherein joined regions that join the non-skin-side sheet and a hydrophobic outer sheet on the non-skin-facing surface side of the non-skin-side sheet are intermittently arranged in a row along the longitudinal direction, and an interval between the joined region rows that are adjacent to each other in the lateral direction is from 4 to 20 mm.
[Claim 41] The disposable diaper according to any one of claims 1 to 40, wherein, in a case where a plurality of the hydrophilic non-skin-side sheets are provided, hydrophilicity increases in accordance with an increase in a distance from the wearer’s skin.
[Claim 42]

The disposable diaper according to any one of claims 1 to 41, wherein, in comparison with the non-skin-side sheet that is adjacent to the skin-side sheet, at least any one of a hydrophilic fiber content with respect to all constituent fibers, a basis weight of the non-skin-side sheet, a Klemm water absorption height, and a saturated water-absorption amount is larger than that of the non-skin-side sheet that is adjacent to the skin-side sheet, in accordance with an increase in a distance from the skin-side sheet.