GB2582462A

GB2582462A - Disposable Diaper

Info

Publication number: GB2582462A
Application number: GB2006280.8A
Authority: GB
Inventors: Ueda Akiyuki; Fukuda Yuko
Original assignee: Kao Corp
Current assignee: Kao Corp
Priority date: 2017-12-27
Filing date: 2018-12-14
Publication date: 2020-09-23
Anticipated expiration: 2038-12-14
Also published as: RU2740088C1; JP7099937B2; CN111225642A; GB202006280D0; GB2582462B; JP2019118800A; CN111225642B; DE112018006678T5

Abstract

This disposable diaper (1) is provided with an absorbent body (2) comprising an absorber (23) and a surface sheet (21). The diaper (1) is equipped with a waist part. The waist part is divided into a ventral section (F) and a dorsal section (R). The dorsal section (R) has, as constituent sheets thereof, a hydrophobic sheet (31E) covering a dorsal end portion (2R) of the absorbent body (2) and a sweat-absorbent sheet (10) disposed on the skin-facing side of the hydrophobic sheet (31E). In a region (Q) where the sweat-absorbent sheet (10) and the absorbent body (2) overlap in the thickness direction, the bonding strength in a first bonding region (7U) where the sweat-absorbent sheet (10) and the hydrophobic sheet (31E) are bonded is greater than the bonding strength in a second bonding region (7D) where the hydrophobic sheet (31E) and the surface sheet (21) are bonded.

Description

Title of Invention: DISPOSABLE DIAPER

Technical Field

[0001] The present invention relates to a disposable diaper provided with a sweat-absorbent sheet having a sweat-absorbent function.

Background Art

[0002] There is a conventionally known disposable diaper, which is configured to include a topsheet disposed to be contactable with a skin of a wearer, a backsheet disposed on a side farther from the skin of the wearer than the topsheet, and an absorbent member interposed between both sheets, in which the absorbent member includes an absorbent core including an absorbent material such as pulp and a core-wrap sheet that covers the absorbent core. In the disposable diaper having such a configuration, in order to reduce skin troubles such as heat rash, a sweat-absorbent sheet including a hydrophilic material capable of absorbing sweat is conventionally disposed at a portion where it may come into contact with the skin of the wearer when worn.

[0003] Patent Literature 1 discloses that a sweat-absorbent sheet is attached to a hydrophobic sheet that covers an inner surface side of a front-rear waist region of the disposable diaper. The sweat-absorbent performance sheet is entirely overlapped with the hydrophobic sheet in the thickness direction, and has a non-joint region not joined with the hydrophobic sheet at a portion on the outside of an inner end of the sweat-absorbent performance sheet and a joint region joined with the hydrophobic sheet at a portion on the outside of the non-joint region. Further, an inner end of the joint region between the hydrophobic sheet and the waist region is disposed on the inside of the inner end of the joint region between the sweat-absorbent performance sheet and the hydrophobic sheet.

Citation List Patent Literature [0004] Patent Literature 1: JP 2007-259874 A

Summary of Invention

[0005] The present invention relates to a disposable diaper provided with an absorbent assembly including a topsheet forming a skin-facing surface, in which a longitudinal direction corresponds to a front-back direction of a wearer and a lateral direction is orthogonal to the longitudinal direction. A waist part disposed at the waist of the wearer when worn is provided, and the waist part is segmented into a front portion disposed on the front side of the wearer when worn and a rear portion disposed on the rear side. At least the rear portion includes, as sheets constituting the rear portion, a hydrophobic sheet disposed at a rear end portion of the absorbent assembly in the longitudinal direction over the longitudinal direction and disposed on a skin-facing side of the absorbent assembly, and a sweat-absorbent sheet disposed a skin-facing side of the hydrophobic sheet. In a region overlapped with the absorbent assembly in the thickness direction, the joining strength of a first joint region in which the sweat-absorbent sheet and the hydrophobic sheet are joined is greater than the joining strength of a second joint region in which the hydrophobic sheet and the topsheet are joined.

Brief Description of Drawings

[0006] [Fig. 1] Fig. 1 is a perspective view schematically illustrating a pull-on disposable diaper that is an embodiment of a disposable diaper according to the present invention.

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

[Fig. 3] Fig. 3 is a lateral cross-sectional view schematically illustrating a cross section taken along a line Il I-Ill (a cross section along the lateral direction) in Fig. 2.

[Fig. 4] Fig. 4 is a lateral cross-sectional view schematically illustrating a cross section taken along a line IV-IV (a cross section along the lateral direction) in Fig. 2.

[Fig. 5] Fig. 5 is a cross-sectional view schematically illustrating a cross section taken along a line V-V (a cross section along the longitudinal direction) in Fig. 2, and is a longitudinal cross-sectional view schematically illustrating an enlarged longitudinal one end (a longitudinal end on the rear side) of the diaper illustrated in Fig. I. [Fig. 6] Fig. 6 is an explanatory view illustrating how a pocket is formed after the diaper illustrated in Fig. 5 is worn.

[Fig. 7] Fig. 7 is a longitudinal cross-sectional view (a view corresponding to Fig. 5) schematically illustrating an enlarged longitudinal one end (a longitudinal end on the rear side) of a diaper as another embodiment of the disposable diaper according to the present invention.

Detailed Description of Invention

[0007] It is preferable that the sweat-absorbent sheet has a configuration in which sweat of a wearer, after it has been absorbed, can easily move away from the skin of the wearer in the thickness direction of the sweat-absorbent sheet. In a disposable diaper provided with the sweat-absorbent sheet, the portion where the sweat-absorbent sheet is disposed is often a portion that easily rubs against the body of the wearer during wearing, and accordingly the sweat-absorbent sheet is easily turned over. In particular, as in the disposable diaper disclosed in Patent Literature 1, when the non-joint region is provided at an inner end portion of the sweat-absorbent performance sheet, the non-joint region is more easily turned over. If the sweat-absorbent sheet having absorbed sweat is turned over in this manner, the sweat that has once moved away from the skin of the wearer will come into contact with the skin of the wearer. Therefore, there is a risk of causing skin troubles such as heat rash if the disposable diaper is kept worn as it is.

[0008] Accordingly, the present invention relates to a disposable diaper in which the sweat-absorbent sheet is hardly turned over during wearing and skin troubles resulting from sweat hardly occur.

[0009] Hereinafter, the present invention will be described based on preferred embodiments with reference to attached drawings. Figs. 1 to 5 illustrate a pull-on disposable diaper 1 that is an embodiment of the disposable diaper according to the present invention. The diaper 1, as illustrated in Figs. 1 to 5, has a longitudinal direction X corresponding to the front-back direction of a wearer, that is, a direction extending from the front side to the rear side via a crotch part, and a lateral direction Y orthogonal thereto. The diaper 1 is equipped with an absorbent assembly 2 including a topsheet 21 that forms a skin-facing surface.

[0010] In the present description, the "skin-facing surface" is a surface of the disposable diaper or a constituent member thereof (e.g., topsheet) that is directed to the skin side of the wearer at the time of wearing the disposable diaper, that is a side that is relatively close to the skin of the wearer, and the "non-skin-facing surface" is a surface of the disposable diaper or a constituent member thereof that is directed to a side opposite to the skin side at the time of wearing disposable diaper, that is, a side relatively far from the skin of the wearer. An addition, "the time of wearing" means a state where normal appropriate wearing position, that is, correct wearing position of the disposable diaper is maintained.

[0011] The diaper 1, as illustrated in Figs. 1 and 2, has a crotch portion M and a front portion F and a rear portion R that extend in the longitudinal direction X from front and rear sides of the crotch portion M. The crotch portion M is a part disposed in the crotch part of the wearer in the worn state of the diaper 1. The front portion F is a part disposed on the front side of the wearer, that is the front side in the longitudinal direction X, rather than the crotch portion M, in the worn state of the diaper I The rear portion R is a part disposed on the rear side of the wearer, that is, the rear side in the longitudinal direction X, rather than the crotch portion M, in the worn state of the diaper 1. The front portion F and the rear portion R constitute a waist part disposed at the waist of the wearer when the diaper 1 is worn. In other words, the diaper 1 has the waist part, and the waist part is segmented into the front portion F and the rear portion R. [0012] The diaper 1 includes the absorbent assembly 2, which includes a liquid-retentive absorbent member 23, in the center in the lateral direction Y, and an outer cover 3 disposed on a side farther from the body of the wearer than the non-skin-facing side of the absorbent assembly 2, that is, the absorbent assembly 2. Both side edges of the front portion F and the rear portion R along the longitudinal direction X of the outer cover 3 are joined together by a known joining means such as adhesive agent, heat seal, or ultrasonic sealing. Thus, as illustrated in Fig. 1, a pair of side seals S and S, a waist opening portion WH through which the torso of the wearer is inserted, and a pair of leg openings LH and LH through which lower limbs of the wearer are inserted are formed.

[0013] The absorbent assembly 2, in its flat-out, uncontracted state of the diaper 1 as illustrated in Fig. 2, has a rectangular shape in plan view, and extends in the longitudinal direction X from the front portion F to the rear portion R. The absorbent assembly 2, while the longitudinal direction thereof is aligned with the longitudinal direction X of the diaper 1 in its flat-out, uncontracted state, is disposed at the center of the outer cover 3 in the lateral direction Y, and joined to the outer cover 3 with an adhesive agent. The "flat-out, uncontracted state" of the diaper 1 is a state in which the diaper 1 is brought into an expanded state by separating the side seals S and the diaper 1 in the expanded state is expanded until the elastic member of each part is caused to extend to design dimensions (that are identical to the dimensions when flattened in a state where the influence of the elastic member is completely eliminated).

[0014] The absorbent assembly 2, as illustrated in Figs. 3 and 4, includes the liquid-permeable topsheet 21 that forms a skin-facing surface, a liquid-impermeable, or sparingly liquid permeable, or water-repellent backsheet 22 that forms a non-skin-facing surface, and the liquid-retentive absorbent member 23 interposed between both the sheets 21 and 22. These members are integrated by a known joining means such as an adhesive agent. The entire length in the longitudinal direction X and the entire length in the lateral direction Y of the topsheet 21 are equal to or longer than the entire length in the longitudinal direction X and the entire length in the lateral direction Y of at least the absorbent member 23, respectively. The topsheet 21 is disposed on the skin-facing side of the absorbent member 23 so as to cover the absorbent member 23. The entire length of the absorbent assembly 2 in the longitudinal direction X is at least the same as the entire length of the absorbent member 23. Both longitudinal ends 23a and 23a of the absorbent member 23, as illustrated in Figs. 2 and 5, are positioned inward in the longitudinal direction X than the longitudinal end of the absorbent assembly 2. As the backsheet 22, various types conventionally used for this kind of disposable diaper can be used without any particular limitations. For example, a resin film or a laminate of a resin film and a nonwoven fabric, or the like can be used as the backsheet 22. The topsheet 21 will be described below.

[0015] The absorbent member 23, as illustrated in Figs. 3 and 4, is configured to include a liquid-retentive absorbent core 24 mainly constituted by an absorbent material and a core-wrap sheet 25 that covers outer surfaces, that is, skin-facing surface and non-skin-facing surface, of the absorbent core 24. The absorbent core 24 has a rectangular shape that is long in the longitudinal direction X, in plan view as illustrated in Fig. 2, and extends in the longitudinal direction X from the front portion F to the rear portion R. As an absorbent material that forms a main part of the absorbent core 24, what is used as the material of the absorbent member in this kind of disposable diaper can be used without any particular limitations. Examples thereof include wood pulp, synthetic fibers subjected to a hydrophilic treatment, and absorbent polymer. As a typical form of the absorbent core 24, there can be exemplified a fiber aggregate of hydrophilic fibers such as wood pulp, or the fiber aggregate holding particulate absorbent polymer.

[0016] In the diaper 1, the core-wrap sheet 25 is a single continuous liquid-permeable sheet that has a width not less than 2 times and not greater than 3 times the length of the absorbent core 24 in the lateral direction Y, and as illustrated in Figs. 3 and 4, covers the whole area of the skin-facing surface of the absorbent core 24, and extends outward in the lateral direction Y from both side edges along the longitudinal direction X of the absorbent core 24. The extension portion is wound downward below the absorbent core 24 so as to cover the whole area of the non-skin-facing surface of the absorbent core 24. The absorbent core 24 and the core-wrap sheet 25 may be joined together by a known joining means such as a hot-melt adhesive agent. For example, liquid-permeable sheets such as papers, various nonwoven fabrics, and apertured films can be used as the core-wrap sheet 25.

[0017] In the present invention, the core-wrap sheet 25 may not be such a single sheet, and for example, may be configured to include single skin-side core-wrap sheet that covers the skin-facing surface of the absorbent core 24, and a single non-skin-side core-wrap sheet that is separate from the skin-side core-wrap sheet and covers the non-skin-facing surface of the absorbent core 24.

[0018] The absorbent assembly 2, as illustrated in Figs. 2 and 3, has leak-proof cuffs 26 on both sides along the longitudinal direction X on the skin-facing surface of the absorbent assembly 2. The leak-proof cuffs 26 on each side is configured to include a water-repellent and air-permeable leak-proof cuff forming sheet 27 that extends continuously over the entire length of the absorbent assembly 2 in the longitudinal direction X and one or more cuff forming elastic members 28 fixed in a stretched state in the longitudinal direction X at one end of the sheet 27 in the lateral direction Y. The leak-proof cuff forming sheet 27 has the other end in the lateral direction Y that is fixed to the non-skin-facing surface of the backsheet 22 of the absorbent assembly 2 by a cuff assembly fixing part 291 extending over the entire length of the absorbent assembly 2 in the longitudinal direction X Further, the leak-proof cuff forming sheet 27 has one end in the lateral direction Y that is fixed to the skin-facing surface of the topsheet 21 on the absorbent member 23 by a free-end fixing part 292, at each of a front end 2F and a rear end 2R of the absorbent assembly 2 in the longitudinal direction X. When the diaper 1 is worn, the contraction force of the cuff forming elastic member 28 acts in the longitudinal direction X, and at least in the crotch portion M, one end of the sheet 27 becomes a free end, and the leak-proof cuffs 26 are formed so as to stand up toward the skin of the wearer with the cuff assembly fixing part 291 as a proximal end. In this manner, the leak-proof cuffs 26 have the free ends fixed to the skin-facing surface of the topsheet 21 by the free-end fixing parts 292, at the front end 2F and the rear end 2R. When the diaper 1 is worn, the elastic member 28 contracts so that the free end on which the cuff forming elastic member 28 is disposed stands up at the crotch portion M. [0019] As illustrated in Figs. 2 and 4, respective leak-proof cuff forming sheets 27 constituting the pair of leak-proof cuffs 26 and 26 disposed on both sides along the longitudinal direction X of the absorbent assembly 2 are disposed over the front end 2F and the rear end 2R of the absorbent assembly 2 in the longitudinal direction X and covered by the folded part 31 E made of a below-described hydrophobic sheet and disposed on the skin-facing side of the absorbent assembly 2. Further, the folded part 31 E is joined with the pair of leak-proof cuffs 26 and 26 to be covered, at the front end 2F and the rear end 2R, via cuffjoint regions 7K and 7K. The means for joining the folded part 31E forming each cuff joint region 7K and the leak-proof cuff forming sheet 27 constituting each leak-proof cuff 26 is not particularly limited, and a known joining means such as an adhesive agent or fusion can be used, although the adhesive agent is used for the diaper 1.

[0020] The outer cover 3 forms the outer shape of the diaper 1 in its flat-out, uncontracted state illustrated in Fig. 2, and the periphery of the outer cover 3 forms contour lines of the diaper 1 in this state, that is, contour lines of the front portion F, the crotch portion M, and the rear portion R. The outer cover 3, as illustrated in Fig. 2, has a rectangular shape in which the length in the lateral direction Y is longer than the length in the longitudinal direction X, in the front portion F and the rear portion R. In the crotch portion M positioned between the front portion F and the rear portion R, both side edges, that is, a pair of leg edges LS and LS, along the longitudinal direction X of the outer cover 3 are curved in a convex arc shape toward the center of in the lateral direction Y, and in plan view as illustrated in Fig. 2, the central region in the longitudinal direction X has a sandglass shape that is bound inward in the lateral direction Y. [0021] The outer cover 3, as illustrated in Figs. 3 to 5, is configured to include a laminated body constituted by an outer sheet 31 that forms an outer surface, that is, a non-skin-facing surface, of the diaper 1 in a worn state, and an inner sheet 32 disposed to be opposed to the skin-facing surface of the outer sheet 31. In the worn state of the diaper 1, the outer sheet 31 is positioned on the side farther from the body of the wearer so as to form the non-skinfacing surface (outer surface) of the diaper 1. The inner sheet 32 is positioned on the side closer to the body of the wearer so as to form the skin-facing surface (inner surface) of the diaper 1. The outer sheet 31 and the inner sheet 32 are joined together through a joining means such as an adhesive agent at a predetermined portion.

[0022] In the diaper 1, as illustrated in Figs. 2 and 5, the outer sheet 31 has the folded part 31E extending from the end edge of the inner sheet 32 in the longitudinal direction X and folded on the skin-facing side of the inner sheet 32, at the front portion F and the rear portion R. In the front portion F, the folded part 31E covers the front end 2F of the absorbent assembly 2 in the longitudinal direction X and is joined with the topsheet 21 of the absorbent assembly 2 via a second joint region 7D. Further, in the rear portion R, the folded part 31E covers the rear end 2R of the absorbent assembly 2 in the longitudinal direction X and is joined with the topsheet 21 of the absorbent assembly 2 via the second joint region 7D. The means for joining the folded part 31E and the topsheet 21, which forms the second joint region 7D, is not particularly limited and a known joining means such as an adhesive agent or fusion can be used, although the adhesive agent is used for the diaper 1.

Although Fig. 5 illustrates an enlarged view of the rear portion R and no enlarged view of the front portion F, the front portion F is similar to the rear portion R in configuration, and unless otherwise mentioned, the description for the rear portion R can be appropriately applied to the front portion F. [0023] As mentioned above, in the diaper 1, as illustrated in Figs. 2 and 4, in the front portion F, the folded part 31E is disposed over the front end 2F of the absorbent assembly 2 in the longitudinal direction X and is also disposed on the skin-facing side of the absorbent assembly 2. Further, the folded part 31 E covers the front end 2F of the absorbent assembly 2 and is joined with the topsheet 21 of the absorbent assembly 2 via the second joint region 7D, and is joined with the pair of leak-proof cuffs 26 and 26 of the absorbent assembly 2 via the cufIjoint regions 7K and 7K. Further, in the front portion F, the folded part 31 E is also joined with the inner sheet 32 of the outer cover 3. Similarly, in the rear portion R, the folded part 31E covers the rear end 2R of the absorbent assembly 2 and is joined with the topsheet 21 of the absorbent assembly 2 via the second joint region 7D, and is joined with the pair of leak-proof cuffs 26 and 26 of the absorbent assembly 2 via the cuff joint regions 7K and 7K. Further, in the rear portion R, the folded part 31 E is also joined with the inner sheet 32 of the outer cover 3. The folded part 31E and the inner sheet 32 are joined together by a joining means such as an adhesive agent at a predetermined portion.

[0024] The sheets 31 and 32 constituting the outer cover 3 may be the same type of sheets or different types of sheets as long as they are hydrophobic sheets. The different types of sheets are, for example, mutually different in elasticity. Specifically, for example, as the outer sheet 31, a hydrophobic stretchable sheet having elasticity in the lateral direction Y may be used. And, as the inner sheet 32, a hydrophobic non-stretchable sheet having no elasticity may be used. Further, for example, the elasticity of the outer sheet 31 may be partly different. Specifically, examples thereof include a form in which a part of the outer sheet 31 positioned in the front portion F and the rear portion R is made of a stretchable sheet having elasticity in the lateral direction Y and a part of the outer sheet 31 positioned in the crotch portion M is made of a non-stretchable sheet having no elasticity.

[0025] Examples of the stretchable sheet usable as the outer cover 3 include a stretchable sheet in which stretchable fiber layers are integrated on both surfaces or one surface of an elastic fiber layer. Examples of the method for integrating the elastic fiber layer and the stretchable fiber layer include a method for laminating and hydro-entangling the both, a method for entangling fibers by air-through or the like, and a method for joining them by heat embossing, an adhesive agent, ultrasonic waves, etc. Further, examples of the non-stretchable sheet usable as the outer cover 3 include nonwoven fabrics produced by various manufacturing methods, and specifically, spunbond nonwoven fabrics, air-through nonwoven fabrics, and needle-punched nonwoven fabrics can be exemplified.

[0026] As illustrated in Figs. 1, 2, and 5, a plurality of filamentous or continuous waist elastic members 33 being in stretched state is disposed in the lateral direction Y, in each of the front portion F and the rear portion R. These waist elastic members 33 are intermittently disposed at a predetermined interval in the longitudinal direction X. As described above, the waist elastic members 33 are disposed in a state where the elastic stretchability can be expressed so that the opening edge of the waist opening portion WET has an annular waist gather that is substantially continuous over the entire circumference. Further, on a leg edge LS that forms the opening edge of each of the pair of leg openings LH and LH, a leg elastic member 34 for forming one or a plurality of filamentous or continuous leg gathers is disposed in stretched state. As a result, an annular leg gather substantially continuous over the entire circumference is formed at the opening edge of each of the pair of leg openings LH and LH. These elastic members 33 and 34 each are sandwiched and fixed between the outer sheet 3 I and the inner sheet 32 that cooperatively constitute the outer cover 3 by a joining means such as an adhesive agent.

[0027] In the diaper 1, as described above, the outer cover 3 is disposed on the side farther from the skin of the wearer of the diaper 1 than the absorbent assembly 2, as illustrated in Fig. 5. Further, since the waist elastic members 33 are fixed in a stretched state in the lateral direction Y, the outer cover 3 is a stretchable sheet that has elasticity in the lateral direction Y. [0028] In the present description "elasticity" means such a property that it is extendable in a predetermined direction and contracts when the extension is released. When the sheet has substantially no elasticity in a certain direction (being non-elastic), it means that the sheet hardly stretches even when a pulling force is applied to the sheet in the certain direction. For example, when a sample being 15 cm in length and 5 cm in width is pulled in the longitudinal direction with a material tensile tester such as Tensilon and the breaking elongation when the sample breaks is not greater than 10%, the sample has substantially no elasticity in the longitudinal direction. The breaking elongation can be calculated by (sample length at breakage -original sample length)/ (original sample length) x 100.

[0029] The rear portion R, as illustrated in Fig. 5, includes a hydrophobic sheet that covers the rear end 2R of the absorbent assembly 2, as a sheet constituting the rear portion R, and a sweat-absorbent sheet 10 disposed on the skin-facing side of the hydrophobic sheet. In the diaper 1, sheets constituting the rear portion R are the outer sheet 31, the inner sheet 32, the folded part 31E of the outer sheet 31, and the sweat-absorbent sheet 10. The folded part 31E of the outer sheet 31 is a hydrophobic sheet covering the rear end 2R of the absorbent assembly 2. In the rear portion R, the elastic members 33 are disposed in stretched state in the lateral direction Y. The rear portion R has elasticity in the lateral direction Y due to the provision of the elastic members 33, as a whole, although the elasticity of the elastic members 33 may be partly impeded.

[0030] The sweat-absorbent sheet 10 is intended to absorb sweat around the waist of the wearer, and is disposed in a portion where it can contact the skin of the wearer when the diaper 1 is worn. In the diaper 1, as illustrated in Figs. 1, 2, 4, and 5, in each of the front portion F and the rear portion R being the waist part disposed at the waist of the wearer when worn, the sweat-absorbent sheet 10 is disposed at a position closer to the skin of the wearer. The sweat-absorbent sheet 10 is joined with the folded part 31E of the outer sheet 31 being the hydrophobic sheet via a first joint region 7U. The means for joining the sweat-absorbent sheet 10 and the folded pan 31E, which forms the first joint region 7U, is not particularly limited and a known joining means such as an adhesive agent or fusion can be used.

From the viewpoint of absorbing sweat, the basis weight of the sweat-absorbent sheet is preferably not less than 12 g/m2, more preferably not less than 15 g/m2, and is preferably not greater than 50 g/m2, more preferably not greater than 45 g/m2.

[0031] In the diaper 1, the sweat-absorbent sheet 10 has a shape that is long in one direction in plan view as illustrated in Fig. 2, specifically a rectangular shape, and is disposed over the entire length in the lateral direction Y of each of the front portion F and the rear portion R, while the longitudinal direction thereof is aligned with the lateral direction Y. In the rear portion R, the sweat-absorbent sheet 10 being long in the lateral direction Y is disposed so as to straddle both of an absorbent member arrangement region in which the absorbent member 23 is disposed and an absorbent member-less region in which the absorbent member 23 is not disposed. The absorbent member-less region includes a region (side flap region) positioned outward in the lateral direction Y from both side edges along the longitudinal direction X of the absorbent member 23 and the imaginary extended line thereof, and a region (end flap region) positioned outward in the longitudinal direction X from the longitudinal end of the absorbent member (the longitudinal end 23a of the absorbent member 23) and the imaginary extended line thereof As described above, the sweat-absorbent sheet 10 is disposed in such a way as to straddle both the absorbent member arrangement region and the absorbent member-less region, in the rear portion R, and is not disposed in the crotch portion M and is disposed in the front portion F or the rear portion R. In this respect, the sweat-absorbent sheet 10 is different from the topsheet 21 that is disposed over the front portion F and the rear portion R. [0032] On the skin-facing side of the rear portion R, the sweat-absorbent sheet 10 is disposed in the vicinity of the opening end of the waist opening portion WH along the opening end. The sweat-absorbent sheet 10, as illustrated in Fig. 5, has an outer end 10a in the longitudinal direction X, which is relatively close to the waist opening portion WH, and an inner end 10b in the longitudinal direction X, which is positioned on the crotch portion M side, which is relatively far from the waist opening portion WII. Both longitudinal ends 10a and 10b extend parallel to the lateral direction Y. The outer end 10a of the sweat-absorbent sheet 10 in the longitudinal direction X is positioned outward in the longitudinal direction X than the longitudinal end 23a of the absorbent member 23, and the inner end 10b of the sweat-absorbent sheet 10 in the longitudinal direction X is positioned inward in the longitudinal direction X than the longitudinal end 23a of the absorbent member 23 The longitudinal end 23a of the absorbent member 23 is also the longitudinal end of the absorbent core 24 or the core-wrap sheet 25.

[0033] In the diaper 1, the sweat-absorbent sheet 10 having a sweat-absorbent function is disposed in a portion where it can be brought into contact with the skin of the wearer (around the waist opening portion WH on the skin-facing surface). Therefore, skin troubles resulting from sweat such as heat rash, eczema, and any other rash can be reduced. In addition, as illustrated in Fig. 5, in a region Q in which the sweat-absorbent sheet 10 and the absorbent assembly 2 are overlapped in the thickness direction, the joining strength of the first joint region 7U in which the sweat-absorbent sheet 10 and the folded part 31 E being a hydrophobic sheet are joined is greater than the joining strength of the second joint region 7D in which the folded part 31E being a hydrophobic sheet and the topsheet 21 of the absorbent assembly 2 are joined. With such a configuration, after the sweat-absorbent sheet 10 absorbs sweat of the wearer wearing the diaper 1, even if the sweat-absorbent sheet having absorbed sweat rubs against the body of the wearer, the sweat-absorbent sheet 10 is hardly turned over while worn, and before the sweat-absorbent sheet 10 is turned over from the folded part 31E the folded part 31E is easily turned over from the topsheet 21. If the sweat-absorbent sheet 10 is turned over and comes into contact with the skin, the sweat-absorbent sheet 10 is doubled in the turned portion so that the sweat absorption amount increases, and accordingly, it is considered that when it directly contacts skin of the wearer skin troubles such as heat rash are likely to occur. On the other hand, in the case of turnover from the topsheet 21, since the folded part 3 1 E is a hydrophobic sheet, skin troubles such as heat rash are unlikely to occur even when the diaper 1 is continuously worn in this state. Further, when the folded part 31 E is turned over from the topsheet 21, as illustrated in Fig. 6, a pocket P is formed between the turned hydrophobic folded part 31E and the topsheet 21. Therefore, leakage of body fluid such as urine from the rear portion R can be prevented.

[0034] From the viewpoint of further exerting the above-mentioned effects, the joining strength of the first joint region 7U is preferably not less than 1.5 times, more preferably not less than 2.0 times, and not greater than 7.5 times, more preferably not greater than 5.0 times, the joining strength of the second joint region 7D. Further, the joining strength of the first joint region 7U is preferably not less than 1.5 times and not greater than 7.5 times, more preferably not less than 2.0 times and not greater than 5.0 times, the joining strength of the second joint region 7D.

Specifically, the joining strength of the first joint region 7U is preferably not less than 1.5 N/25 mm, more preferably not less than 2.0 N/25 mm, and is preferably not greater than 25 N/25 mm, more preferably not greater than 20 N/25 mm, and is preferably not less than 1.5 N/25 mm and not greater than 25 N/25 mm, more preferably not less than 2.0 N/25 mm and not greater than 20 N/25 mm.

The joining strength of the second joint region 7D is preferably not less than 0.5 N/25 mm, more preferably not less than 1.0 N/25 mm, and is preferably not greater than 3.0 N/25 mm, more preferably not greater than 2.5 N/25 mm, and is preferably not less than 0.5 N/25 mm and not greater than 3.0 N/25 mm, more preferably not less than 1.0 N/25 mm and not greater than 2.5 N/25 mm.

The joining strength of the first joint region 7U and the joining strength of the second joint region 7D can be measured by the following method.

[0035] <Joining strength measuring method> In a 22°C65%RH environment, a disposable diaper is stretched to such an extent that the gathers formed by the contraction of each elastic member disappear, a measurement piece having a rectangular shape that is long in the longitudinal direction X, 25 mm in the lateral direction Y, and 40 mm in the longitudinal direction X, is cut out, so as to include the region Q in which the sweat-absorbent sheet 10 and the absorbent assembly 2 are overlapped in the thickness direction. The cutting of the measurement piece is performed in such a manner that a portion corresponding to the overlapping region Q is located at least at one end of the measurement piece in the longitudinal direction X. Next, for example, when measuring the joining strength of the first joint region 7U, the sweat-absorbent sheet 10 and the folded part 31E being a hydrophobic sheet are peeled of at a portion therebetween on the other end side of the measurement piece in the longitudinal direction X. Then, the measurement piece is aligned so that the longitudinal direction X coincides with the tensile direction, and the part of the sweat-absorbent sheet 10 and the part of the folded part 31E that have been peeled off are attached to an upper chuck and a lower chuck of a tensile tester (e.g., Tensilon tensile tester "RTA-100" manufactured by ORTENTEC CORPORATION). In this case, the clearance between both chucks is set to 10 mm. Then, while the position of the lower chuck is fixed, the upper chuck is moved upward at the speed of 300 mm/min. As the upper chuck rises, the measurement piece breaks in the longitudinal direction X and is separated into the sweat-absorbent sheet 10 and the folded part 31E. The breaking strength is measured until the length of the broken portion reaches 25 mm, and the maximum value is obtained. This measurement is repeated five times, and an average value of the measured values is defined as the joining strength of the first joint region 7U. When measuring the joining strength of the second joint region 7D, the folded part 31E being a hydrophobic sheet and the topsheet 21 are peeled off at a portion therebetween on the other end side of the measurement piece in the longitudinal direction X. Then, the part of the folded part 31E and the part of the topsheet 21 that have been peeled off are attached to the upper chuck and the lower chuck. Subsequently, similarly to the joining strength of the first joint region 7U, the joining strength of the second joint region 7D is measured.

[0036] From the viewpoint of causing the folded part 31E to be more easily turned over from the topsheet 21, before the sweat-absorbent sheet 10 is turned over from the folded part 31E, when the topsheet 21 and the sweat-absorbent sheet 10 are moved following the movement of the skin while the diaper 1 is worn, it is preferable that the sweat-absorbent sheet 10 and the absorbent core 24 are overlapped in the region Q in which the sweat-absorbent sheet 10 and the absorbent assembly 2 are overlapped in the thickness direction. This is because the topsheet 21 disposed near the absorbent core 24 is easier to deform constituent fibers following the movement of the skin, compared with the sweat-absorbent sheet 10 disposed farther from the absorbent core 24 than the topsheet 21, and therefore the second joint region 7D where the folded part 31E and the topsheet 21 are joined is easily distorted and easily peeled off [0037] From the viewpoint of further easily forming the pocket P illustrated in Fig. 6 between the hydrophobic folded part 31E and the topsheet 21 and further preventing the leakage of body fluid such as urine from the rear portion R, at least in the rear portion R, the joining strength of the cuff joint region 7K of each leak-proof cuff 26 is preferably greater than the joining strength of the second joint region 7D, more preferably not less than 1.5 times, even more preferably not less than 2.0 times, and is more preferably not greater than 7.5 times, more preferably not greater than 5.0 times, and is more preferably not less than 1.5 times and not greater than 7.5 times, more preferably not less than 2.0 times and not greater than 5.0 times.

Specifically, the joining strength of the cuff joint region 7K of each leak-proof cuff 26 is preferably not less than 1.5 N/25 mm, more preferably not less than 2.0 N/25 mm, and is preferably not greater than 15 N/25 mm, more preferably not greater than 10 N/25 mm, and is preferably not less than 1.5 N/25 mm and not greater than 15 N/25 mm, more preferably not less than 2.0 N/25 mm and not greater than 10 N/25 mm.

The joining strength of the cuff joint region 7K of each leak-proof cuff 26 can be measured by the following method.

[0038] <Cuffjoint region 7K joining strength measuring method> In the 22°C65%RH environment, a disposable diaper is stretched to such an extent that the gathers formed by the contraction of each elastic member disappears, a measurement piece having a rectangular shape that is long in the longitudinal direction X, 25 mm the lateral direction Y, and 40 mm in the longitudinal direction X, is cut out, so as to include the cuff joint region 7K. The cutting of the measurement piece is performed in such a manner that the cuff] oint region 7K is located at least at one end of the measurement piece in the longitudinal direction X. Next, the leak-proof cuff forming sheet 27 and the folded part 31E being a hydrophobic sheet are peeled off at a portion therebetween on the other end side of the measurement piece in the longitudinal direction X. Then, the measurement piece is aligned so that the longitudinal direction X coincides with the tensile direction, and the part of the leak-proof cuff forming sheet 27 and the part of the folded part 3 I E that have been peeled off are attached to the upper chuck and the lower chuck of the tensile tester (e.g., Tensilon tensile tester "RTA-100" manufactured by ORIENTEC CORPORATION). In this case, the clearance between both chucks is set to 10 mm. Then, while the position of the lower chuck is fixed, the upper chuck is moved upward at the speed of 300 mm/min. As the upper chuck rises, the measurement piece breaks in the longitudinal direction X and is separated into the leak-proof cuff forming sheet 27 and the folded part 31E. The breaking strength is measured until the length of the broken portion reaches 10 mm, and the maximum value is obtained. This measurement is repeated five times, and an average value of the measured values is defined as the joining strength of the cuff joint region 7K.

[0039] From the viewpoint of preventing the sweat-absorbent sheet from forming a doubled portion where the sweat-absorbing amount is large when it is turned over and preventing it from coming into contact with the skin, it is preferable, as illustrated in Fig. 5, that the inner end 10b of the sweat-absorbent sheet 10 in the longitudinal direction X is located at the same position in the longitudinal direction X as an inner end 31E1 of the hydrophobic folded part 31E in the longitudinal direction X, or located outward in the longitudinal direction X than the inner end 31 El of the folded part 31 E. It is more preferable that it is located outward in the longitudinal direction X than the inner end 31E1 of the folded part 31E. This is because, the sweat-absorbent sheet 10 is hardly turned over due to the inner end 10b of the sweat-absorbent sheet 10 during wearing of the diaper 1.

[0040] From the viewpoint of causing the folded part 31E to be more easily turned over from the topsheet 21, it is preferable, as illustrated in Fig. 5, that an inner end 7U1 in the longitudinal direction X of the first joint region 7U in which the sweat-absorbent sheet 10 and the folded part 3 I E are joined is located at the same position in the longitudinal direction X as an inner end 7D1 in the longitudinal direction X of the second joint region 7D in which the folded part 31E and the topsheet 21 are joined, or located inward than the inner end 7D] of the second joint region 7D in the longitudinal direction X. It is more preferable that it is located inward than the inner end 7D1 of the second joint region 7D in the longitudinal direction X. [0041] From the viewpoint of easily forming the three-dimensional shape of the pocket P to be formed between the hydrophobic folded part 3 IE and the topsheet 21 and further preventing the leakage of body fluid such as urine from the rear portion R, at least in the rear portion R, it is preferable that the folded part 31E made of a hydrophobic sheet that covers the rear end 2R of the absorbent assembly 2 extends to reach a region located inward in the longitudinal direction X than the free-end fixing part 292 (see Fig. 4) disposed at an innermost end of each leak-proof cuff 26 in the lateral direction Y and is joined with each leak-proof cuff 26. In other words, it is preferable that the cuff joint region 7K (see Fig. 2) of each leak-proof cuff 26 extends to a region located inward in the longitudinal direction X than the free-end fixing part 292.

[0042] From the viewpoint of causing the folded part 31E to be more easily turned over from the topsheet 21 before the sweat-absorbent sheet 10 is turned over from the folded part 31E, it is preferable that the inter-fiber distance of the topsheet 21 is greater than the inter-fiber distance of the sweat-absorbent sheet 10. This is because, when the inter-fiber distance of the topsheet 21 is larger, the folded part 31E and the topsheet 21 are joined at a smaller number of points and the joining strength is likely to be lower. When the topsheet 21 has a laminate structure, the inter-fiber distance of the layer closest to the skin-facing side that easily affects the joining strength with the folded part 3 lEis measured. Similarly, when the sweat-absorbent sheet 10 has a laminate structure, the inter-fiber distance of the layer closest to the non-skin-facing side that easily affects the joining strength with the folded part 31 E is measured. The inter-fiber distance of the topsheet 21 is preferably not greater than 250pm, more preferably not greater than 150 am, and is preferably not less than 50 him, more preferably not less than 70 him. Specifically, it is preferably not less than 50 [lin and not greater than 250 him, more preferably not less than 70 pm and not greater than 150 pm. The inter-fiber distance of the sweat-absorbent sheet 10 is preferably not greater than 150 him, more preferably not greater than 90 pm, and is preferably not less than 5 pm, more preferably not less than 10 Rm. Specifically, it is preferably not less than 5 am and not greater than 150 pm, more preferably not less than 10 hun and not greater than 70 pm. Further, the difference between the inter-fiber distance of the topsheet 21 and the inter-fiber distance of the sweat-absorbent sheet 10 is preferably not less than 20 pm, more preferably not less than 30 pm and is preferably not greater than 100 pm, more preferably not greater than 90 pm, as a value obtainable by subtracting the latter from the former.

The inter-fiber distance of the topsheet 21 and the inter-fiber distance of the sweat-absorbent sheet 10 can be measured by the following method.

[0043] <Inter-fiber distance measuring method> The inter-fiber distance of a fiber aggregate such as a nonwoven fabric or a paper can be obtained by the following formula (1) based on the assumption of Wrotnowski.

The following formula (1) is generally used when determining the inter-fiber distance of the fiber aggregate. Under the assumption of Wrotnowski, fibers are columnar and respective fibers are regularly arranged without crossing.

When the sheet to be measured has a single-layer structure, the inter-fiber distance of the single-layer structured sheet can be obtained by the following formula (1).

When the sheet to be measured has a multilayer structure such as an SMS nonwoven fabric, the inter-fiber distance of the multilayer structured sheet can be obtained by the following procedure.

First, the inter-fiber distance of each fiber layer constituting the multilayer structure is calculated by the following formula (I). At that time, thickness t, basis weight W, fiber resin density p, and fiber diameter D used in the following formula (1) are respectively those of the layer to be measured. The thickness t, the basis weight W, and the fiber diameter D are average values obtained from measurement values at a plurality of measuring points, respectively.

The following method is used to measures the thickness t(mm). First, a measurement object sheet is cut into the size of 50 mm in the longitudinal direction and 50 mm in the width direction to produce a cut piece of the sheet. Next, this cut piece is placed on a flat plate, and subsequently a flat glass plate is placed thereon. Further, a weight is placed evenly on the glass plate so that the load including the glass plate becomes 49 Pa, and the thickness of the cut piece is measured. As the measurement environment, the temperature is set to 20±2°C and the relative humidity is set to 65±5%. As a measuring equipment, a microscope (manufactured by Keyence Corporation, V H X-1000) is used. In measuring the thickness of the cut piece, first, an enlarged photo of a cut surface of the cut piece is obtained, so that this enlarged photo includes an image of an object having a known size at the same time. Next, the scale is matched with the enlarged photo of the cut surface of the cut piece, and the thickness of the cut piece, that is, the thickness of the measurement object sheet, is measured. The above operations are performed three times, and an average value of the three is defined as the thickness t of the measurement object sheet. When the measurement object sheet is a laminated product, the boundary is determined from the fiber diameter, and the thickness is calculated.

The basis weight W (g/m2) can be obtained by cutting the measurement object sheet into a predetermined size (e.g., 12 cm x 6 cm), and after mass measurement, dividing the mass measurement value by an area obtained from the predetermined size ("basis weight W(g/m2) = mass ± area obtained from predetermined size"). The above measurement is performed four times, and an obtained average value is defined as the basis weight.

The fiber resin density p (g/cm3) is measured using a density gradient tube in accordance with the measuring method of the density gradient tube method described in JIS L1015 Testing method for chemical staple fibers (refer to http://kikakurui.com/l/L10152010-01.html, or JIS Handbook for fibers-2000 (Japanese Standards Association), P.764 to 765).

To obtain the fiber diameter D (pm), ten cross sections of cut fibers are measured using S-4000 field emission-type scanning electron microscope manufactured by Hitachi, Ltd, and an obtained average value is defined as the fiber diameter. The method for measuring the fiber diameter D follows <Fiber diameter measuring method> described below.

Next, the inter-fiber distance of each layer is multiplied by the ratio of the thickness of the layer to the total thickness of the multilayer structure, and further by totaling numerical values of the layers thus obtained, the inter-fiber distance of a target constituent fiber of the multilayer structured sheet can be obtained. For example, in an SMS nonwoven fabric having a three-layered structure constituted by a two-layered S layer and a single-layered M layer, in which the two-layered S layer is regarded as one layer, when the entire thickness t of the three-layered structure is 0.11 mm, the thickness t of the S layer is 0.1 mm, the inter-fiber distance LS of the S layer is 47.8 pm, the thickness t of the NI layer is 0.01 mm, the inter-fiber distance LS of the M layer is 3.2 pm, the inter-fiber distance of the constituent fiber of such an SMS nonwoven fabric is 43.8 pm [=(47.9 x 0.1 + 3.2 x 0.01)/ 0.11].

[0044] [Numerical Expression I] D p fiver diameter (m) fiber resin density(g/cm3) thickness (mm) basis weight (g/m2) * * Average inter-fiber IL p 702 lob i D (1) distance (pm) -'f 4 * W * 109 [0045] From the viewpoint of causing the folded part 31E to be more easily turned over from the topsheet 21, before the sweat-absorbent sheet 10 is turned over from the folded part 31E, when the topsheet 21 and the sweat-absorbent sheet 10 are moved following the movement of the skin while the diaper I is worn, it is preferable that the thickness t2 I of the topsheet 21 is greater than the thickness t10 of the sweat-absorbent sheet 10. This is because the topsheet 21 having a larger thickness is easier to deform constituent fibers, compared with the sweat-absorbent sheet 10, and therefore the second joint region 7D where the folded part 31E and the topsheet 21 are joined is easily distorted and easily peeled off.

[0046] The thickness t21 of the topsheet 21 is preferably not greater than 5 mm, more preferably not greater than 3 mm, and is not less than 0.2 mm, more preferably not less than 0.5 mm. Specifically, it is preferably not less than 0.2 mm and not greater than 5 mm, more preferably not less than 0.5 mm and not greater than 3 mm. The thickness t10 of the sweat-absorbent sheet 10 is preferably not greater than 2 mm, more preferably not greater than 1 mm, and is preferably not less than 0.1 mm, more preferably not less than 0.2 mm.

Specifically, it is preferably not less than 0.1 mm and not greater than 2 mm, more preferably not less than 0.2 mm and not greater than 1 mm. Further, the difference between the thickness t21 of the topsheet 21 and the thickness tIO of the sweat-absorbent sheet 10 is preferably not less than 0.8 mm, more preferably not less than 1 mm, and is preferably not greater than 4 mm, more preferably not greater than 3 mm, as a value obtainable by subtracting the latter from the former.

The thickness t21 of the topsheet 21 and the thickness tIO of the sweat-absorbent sheet 10 can be measured by the thickness measuring method in the above-described interfiber distance measuring method.

[0047] From the viewpoint of causing the folded part 31E to be more easily turned over from the topsheet 21 before the sweat-absorbent sheet 10 is turned over from the folded part 31E, it is preferable that the fiber diameter D2I of constituent fibers of the topsheet 21 is greater than the fiber diameter D10 of constituent fibers of the sweat-absorbent sheet 10. This is because, when the topsheet 21 is larger in fiber diameter, the folded part 3 1 E and the topsheet 21 are joined at a smaller number of points and the joining strength is likely to be lower, compared with the sweat-absorbent sheet 10.

[0048] The fiber diameter D21 of the topsheet 21 is preferably not greater than 25 Jim, more preferably not greater than 20 jtm, and is preferably not less than 8 pm, more preferably not less than 10 um. Specifically, it is preferably not less than 8 jun and not greater than 25 pm, more preferably not less than 10 jun and not greater than 20 p.m. The fiber diameter D10 of the sweat-absorbent sheet 10 is preferably not greater than 20 him, more preferably not greater than 18 p.m, and is preferably not less than 1 p.m, more preferably not less than 5 p.m. Specifically, it is preferably not less than 1 p.m and not greater than pm, more preferable not less than 5 pm and not greater than 18 Rm. Further, the difference between the fiber diameter D21 of the topsheet 21 and the fiber diameter DIO of the sweat-absorbent sheet 10 is preferably not less than 2 Rm, more preferably not less than 3 him, and is preferably not greater than 10]tm, more preferably not greater than 8 htm, as a value obtainable by subtracting the latter from the former.

The fiber diameter D21 of the topsheet 21 and the fiber diameter DIO of the sweat-absorbent sheet 10 can be measured by the fiber diameter measuring method in the above-described inter-fiber distance measuring method.

[0049] From the viewpoint of causing the folded part 31E to be more easily turned over from the topsheet 21, before the sweat-absorbent sheet 10 is turned over from the folded part 31E, it is preferable that the topsheet 21 has an uneven shape on the skin-facing surface thereof, as illustrated in Figs. 3 to 5. This is because, when the topsheet 21 is joined with the sweat-absorbent sheet 10 via only a projection of the uneven shape on the skin-facing surface thereof, the folded part 31E and the topsheet 21 are joined at a smaller number of points and the joining strength is likely to be lower. The uneven shape on the skin-facing surface of the topsheet 21 is not particularly limited, and the uneven shape of topsheet in this kind of disposable diaper can be appropriately adopted. Examples of the uneven shape include a form in which a plurality of projections is disposed in a scattered manner in the whole area of the skin-facing surface of the topsheet and the periphery of each projection is depressed. The shape of the projection in plan view is not particularly limited, and may be appropriately selected from a circle, an ellipse, and a quadrilateral or more polygon. Specifically, for example, it may be desirable to provide, on the skin-facing surface of the topsheet 21, first depressions linearly arrayed in plan view and extending in a first direction that intersects both the longitudinal direction X and the lateral direction Y and second depressions linearly arrayed in plan view and extending in a second direction that intersects the first direction, so that the first and second depressions are disposed in a grid pattern, and a projection is present in each of a plurality of sections surrounded by both of the depressions. Further, as another example of uneven shape, it may be desirable to provide projections serving as ridges extending in the longitudinal direction X or in the lateral direction Y and depressions serving as grooves extending in the same direction, so that they are alternately disposed in a direction orthogonal to the extending directions thereof Moreover, the projections (ridges) constituting the uneven shape may have a solid structure whose inside is filled with constituent fibers of the topsheet or a hollow structure. Examples of the topsheet having hollow-structured projections include a form in which two sheets are partly joined in a laminated state, and a sheet that is relatively close to the skin of the wearer protrudes away from the other sheet (the sheet that is relatively far from the skin of the wearer), at a portion other than the joint region thereof, to form a plurality of projections protruding toward the skin side of the wearer. In addition, as illustrated in Figs. 3 and 4, it is usual that the non-skin-facing surface of the topsheet 21 is a flat surface that has substantially no uneven shape.

[0050] As the topsheet 21, a liquid-permeable sheet material conventionally used in this kind of disposable diaper can be used. Examples thereof include various nonwoven fabrics such as nonwoven fabrics manufactured by the card method, air-through nonwoven fabrics, spunbond nonwoven fabrics, meltblown nonwoven fabrics, spunlaced nonwoven fabrics and needle-punched nonwoven fabrics, and also include films made liquid permeable by an opening means. These nonwoven fabrics and films may be subjected to a hydrophilic treatment using a hydrophilizing agent such as a surfactant. The basis weight of the topsheet 21 is preferably not less than 12 g/m2, more preferably not less than 15 g/m2, and is preferably not greater than 50 g/m2, more preferably not greater than 45 g/m2.

[0051] In the diaper 1, as mentioned above, at the front portion F and the rear portion R being the waist part disposed at the waist of the wearer when worn, the below-waist elastic members 33 are disposed in stretched state in the lateral direction Y, and a stretchable region constituted by the below-waist elastic members 33 is formed in each of the front portion F and the rear portion R. Therefore, by devising the stretchable region having elasticity in the lateral direction Y, it is feasible to more easily form the pocket P illustrated in Fig. 6 between the hydrophobic folded part 31E and the topsheet 21. Specifically, in the diaper 1, as illustrated in Fig. 2, at least in the rear portion R, a region KT located at the same position in the longitudinal direction X as a region K where the folded part 31 E being a hydrophobic sheet and the topsheet 21 are overlapped in the thickness direction is segmented into a central region KT1 where the absorbent assembly 2 is positioned and a pair of side regions KT2 and KT2 positioned outward in the lateral direction Y from respective both side edges along the longitudinal direction X of the absorbent assembly 2. Further, it is preferable that the central region KT1 is lower in extension stress in the lateral direction Y, compared with each side region KT2. This is because, when the extension stress in the lateral direction Yin the central region KT1 is lower than the extension stress in the lateral direction Y in each side region KT2, at least in the rear portion R, the pocket P formed in the central region KT1 is less likely to be crushed. Examples of the method for reducing the extension stress in the lateral direction Y in the central region KT I include a method for applying processing such as fine division to at least a part of respective waist elastic members 33 disposed in stretched state in the lateral direction Y, in the region overlapped with the absorbent assembly 2 in the thickness direction, so that the elastic stretchability is not expressed, in each of the front portion F and the rear portion R. The extension stress can be measured by the following method.

[0052] <Extension stress measuring method> The diaper 1 is developed and flattend, and the central region KT1 and each side region KT2 are cut out along a straight line parallel to the lateral direction Y of the diaper 1 to obtain measurement pieces of a rectangular shape being long in the lateral direction Y and 70 mm in the lateral direction Y and 25 mm in the longitudinal direction X. The outer cover 3 including the sweat-absorbent sheet 10 from which the absorbent assembly 2 is removed is used in this cutting, and the measurement piece is cut from the outer cover 3. Both ends of the measurement piece in the longitudinal direction (the lateral direction Y) are sandwiched between chucks of Tensilon Universal Testing Machine (RTC-1210A) manufactured by ORIENTEC Co. Ltd., in a state where the clearance between both chucks is set to 30 mm. Then, while the measurement piece is elongated in the longitudinal direction at the speed of 300 mm/min, the stress of the measurement sample at that time is measured. Specifically, when the length of the measurement piece in the lateral direction Yin a state where the sheets 31 and 32 of the outer cover 3 are not contracted by the elastic member 33 is 100, the tensile load (cN) measured when the measurement piece is contracted to a length corresponding to 70 after once extending to a length corresponding to 90 is defined as the extension stress of the measurement piece. The extension stress of the measurement piece, that is the extension stress of the central region KT1 and the extension stress of each side region KT2, can be calculated as an average stress by conversion into a value per length in the longitudinal direction (the lateral direction Y) of each region.

The reason why the extension stress of the measurement piece is defined as the return force at the length corresponding to 70 when the length of the measurement piece in the lateral direction Y in a non-contracted state is 100, as described above, is because it is assumed to be the length at the time of wearing the diaper.

[0053] The ratio of the extension stress in the lateral direction Yin each side region KT2 to the extension stress in the lateral direction Y in the central region KT]. (each side region KT2/central region KU) is preferably not less than 1.2, more preferably not less than 1.5, and is preferably not greater than 4.0, more preferably not greater than 3.5.

The extension stress in the lateral direction Y in the central region KT1 is preferably not less than 5 cN/mm, more preferably not less than 7.5 cN/mm, and is preferably not greater than 25 cN/mm, more preferably not greater than 20 cN/mm.

The extension stress in the lateral direction Y in each side region KT2 is preferably not less than 2 cN/mm, more preferably not less than 3 cN/mm, and is preferably not greater than 15 cN/mm, more preferably not greater than 12 cN/mm.

[0054] The sweat-absorbent sheet 10 is typically a nonwoven fabric. As the nonwoven fabric constituting the sweat-absorbent sheet 10, nonwoven fabrics manufactured by various methods and usable as the constituent member of this kind of disposable diaper can be used without any particular limitations. However, from the viewpoint of leaving no sweat absorbed on the skin-facing side, it is preferable that the sweat-absorbent sheet 10 is a sheet having a skin-facing side that is lower in hydrophilicity compared with that of a non-skin-facing side thereof [0055] As an index representing the hydrophilicity of the surface (skin-facing surface or non-skin-facing surface) of the sweat-absorbent sheet 10, the contact angle with water measured by the following method can be used. It can be determined that when the contact angle with water measured by the following method is smaller the hydrophilic is higher (hydrophobic is lower), and when the contact angle is larger the hydrophilicity is lower (hydrophobicity is higher).

The contact angle between the skin-facing surface of the sweat-absorbent sheet 10 and ion-exchanged water is preferably not less than 90°, more preferably not less than 100°, and is preferably not greater than 1500, more preferably not greater than 140°. Specifically, it is preferably not less than 90° and not greater than 150°, more preferably not less than 100° not greater than 140°.

Further, the contact angle between the non-skin-facing surface of the sweat-absorbent sheet 10 and the ion-exchanged water is preferably smaller than 90°, more preferably not greater than 88°, and even more preferably not greater than 85°, and is preferably not less than 35°, more preferably not less than 40°. Specifically, it is preferably not less than 35° and smaller than 90°, more preferably not less than 35° not greater than 88°, even more preferably not less than 40° and not greater than 85°.

[0056] <Fiber layer (nonwoven fabric) contact angle measuring method> From a measurement object fiber layer (nonwoven fabric), a rectangle shape in plan view of 150 mm in MD direction being a mechanical direction at the time of manufacturing the nonwoven fabric and 70 mm in CD direction being orthogonal to the MD direction is cut out as a measurement sample. A droplet of ion-exchanged water is attached to the surface to be measured of the contact angle in the measurement sample, the droplet is recorded, and the contact angle is measured based on the recorded image. More specifically, the microscope VI-IX-1000 manufactured by Keyence Corporation is used as a measuring device, and a medium-magnification zoom lens is attached to this while it is tilted to 90°. The measurement sample is set on a measurement stage of the measuring device, so that the surface to be measured is directed upward and can be observed from the CD direction of the measurement sample. Then, 31.11_, droplet of ion-exchanged water is attached to the measuring object surface of the measurement sample set on the measurement stage, and an image of the droplet is recorded and taken into the measuring device. Of the recorded plurality of images, ten images that clearly show both ends or one end of the droplet in the CD direction are selected. The contact angle of the droplet is measured for each of the ten images, and an average value of the measured contact angles is defined as the contact angle of the measurement object fiber layer (nonwoven fabric). The measurement environment is set to 20°C/50%RH.

[0057] The form of the sweat-absorbent sheet having the magnitude correlation of "skin-facing surface < non-skin-facing surface" with respect to the hydrophilicity is not particularly limited, and may have a single-layer structure. A preferable embodiment of such a sweat-absorbent sheet is a laminated nonwoven fabric having a laminate structure including a first layer that forms a skin-facing surface and a second layer that forms a nonskin-facing surface, in which the first layer is lower in hydrophilicity compared with the second layer.

[0058] In the laminated nonwoven fabric, one or more other layers may be interposed between the first layer and the second layer, as a laminate structure. Further, it is preferable that the plurality of layers constituting the laminate structure are joined together and integrated. The joint region is preferably an interlaminar fusion part in which the thickness is smaller compared with the peripheral portion and respective layers constituting the laminate structure are fused together. Such a fusion part can be formed by applying squeezing processing with fusion promoting means for promoting melting of constituent fibers (thermoplastic fibers), such as heat and ultrasonic waves, specifically, for example, heat sealing processing or ultrasonic sealing, on the laminate structure. Moreover, it is preferable that a plurality of fusion parts is present in in a scattered manner on the skin-facing surface and/or non-skin-facing surface of the laminated nonwoven fabric. The fusion part may be recessed in a concave shape from the skin-facing side to the non-skinfacing side, and conversely, it may be recessed in a concave shape from the non-skin-facing side to the skin-facing side, although the former is preferable. Like the laminated nonwoven fabric, the single-layer structured nonwoven fabric may have a fusion part where the constituent fibers (thermoplastic fibers) are fused together.

[0059] When the sweat-absorbent sheet 10 has the fusion part, from the viewpoint of adhesive property to the folded part 31 E being a hydrophobic sheet, it is preferable that the fusion part is disposed on the skin-facing surface of the sweat-absorbent sheet. The form in which the fusion part is disposed on the skin-facing surface of the sweat-absorbent sheet includes not only a form in which the fusion part is only disposed on the skin-facing side, of the skin-facing surface and the non-skin-facing surface of the sweat-absorbent sheet, but also a form in which the fusion part is disposed on both of the skin-facing surface and the non-skin-facing surface. In the case where the fusion part is disposed on both the skin-facing surface and the non-skin-facing surface, it is preferable that the depression depth of the fusion part is greater on the skin-facing side than on the non-skin-facing side.

[0060] As fibers constituting the main part (the fibers occupying preferably 70 mass % or more of all constituent fibers of the first layer) of the first layer of the laminated nonwoven fabric (the layer forming the skin-facing surface), for example, hydrophobic thermoplastic fibers (fusion bond fibers) can be used. Examples of the material for the hydrophobic thermoplastic fibers include polyolefins such as polyethylene and polypropylene; polyesters such as polyethylene terephthalate; polyamides such as nylon 6 and nylon 66; polyacrylic acid, polymethacrylic acid alkyl ester, polyvinyl chloride, and polyvinylidene chloride, as hydrophobic thermoplastic resins. One of these can be used alone, or two or more can be used in combination.

[0061] Further, as the fibers constituting the main part (the fibers occupying preferable 70 mass °A, or more of all constituent fibers of the second layer) of the second layer of the laminated nonwoven fabric (the layer forming the non-skin-facing surface), hydrophilic thermoplastic fibers (fusion bond fibers) can be used. Specifically, for example, inherently hydrophilic thermoplastic fibers such as polyacrylonitrile fibers may be used. Alternatively, hydrophobic thermoplastic fibers usable in the first layer may be subjected to a hydrophilic treatment. One of these can be used alone, or two or more can be used in combination. Examples of the latter "thermoplastic fibers subjected to the hydrophilic treatment" include thermoplastic fibers kneaded with a hydrophilizing agent, thermoplastic fibers with a hydrophilizing agent attached to the surface thereof, and thermoplastic fibers treated with plasma. The hydrophilizing agent is not particularly limited as long as it is a general hydrophilizing agent usable for hygiene products. Further, fibers that are inherently hydrophilic, for example, natural or semi-natural fibers such as cellulose fibers can be used.

[0062] Each of the first layer and the second layer constituting the laminated nonwoven fabric may be short-fiber nonwoven fabrics mainly constituted by short fibers, or may be long-fiber nonwoven fabrics mainly constituted by long fibers. Examples the short-fiber nonwoven fabrics include air-through nonwoven fabrics, spunlaced nonwoven fabrics, needle-punched nonwoven fabrics, and chemically bonded nonwoven fabrics. Examples of the long-fiber nonwoven fabrics include single-layer nonwoven fabrics such as spunbond nonwoven fabrics and meltblown nonwoven fabrics, or laminated nonwoven fabrics in which spunbond layers and meltblown layers mainly constituted by long fibers are laminated, or heat roller nonwoven fabrics according to the card method. Examples of the laminated nonwoven fabrics include spunbond-spunbond lamination nonwoven fabric (SS nonwoven fabrics), spunbond-spunbond-spunbond lamination nonwoven fabrics (SSS nonwoven fabrics), spunbond-meltblown-spunbond lamination nonwoven fabrics (SMS nonwoven fabrics), and spunbond-meltblown-meltblown-spunbond nonwoven fabrics (SMMS nonwoven fabrics).

[0063] The basis weight of the first layer constituting the laminated nonwoven fabric (the layer forming the skin-facing surface) is preferably not less than 8 g/m2, more preferably not less than 10 g/m2, and is preferably not greater than 30 g/m2, more preferably not greater than 25 g/m2.

The basis weight of the second layer constituting the laminated nonwoven fabric (the layer forming the non-skin-facing surface) is preferably not less than 10 g/m2, more preferably not less than 13 g/m2, and is preferably not greater than 40 g/m2, more preferably not greater than 35 g/m2.

[0064] Fig. 7 illustrates another embodiment of the present invention. In another embodiment described below, configurations different from those of the above-mentioned diaper I are mainly described, and similar components are denoted by the same reference numerals and redundant description thereof is avoided. The above description about the diaper 1 is appropriately applied to configurations not specifically described below.

[0065] The diaper 1 illustrated in Fig 7 is different from the above-mentioned diaper I illustrated in Figs. 1 to 5 in the arrangement of leak-proof cuffs 26 disposed on both sides along the longitudinal direction X on the skin-facing surface of the absorbent assembly 2. Specifically, in the diaper I illustrated in Fig. 4, the other end of the leak-proof cuff forming sheet 27 in the lateral direction Y is fixed to the non-skin-facing surface of the backsheet 22 of the absorbent assembly 2 by the cuff assembly fixing part 291. Thus, the leak-proof cuffs 26 are formed so that one end of the sheet 27 stands up as the free end, with the cuff assembly fixing part 291 as a proximal end, when the contraction force of the cuff forming elastic member 28 acts. In this manner, the cuff assembly fixing part 291 of the leakproof cuffs 26 is disposed between the backsheet 22 and the outer cover 3 and is disposed inward in the lateral direction Y than the side edge along the longitudinal direction X of the absorbent member 23. On the other hand, in the diaper 1 illustrated in Fig. 7, the other end of the leak-proof cuff forming sheet 27 in the lateral direction Y is fixed by the cuff assembly fixing part 291 disposed outward in the lateral direction Y than the side edge along the longitudinal direction X of the absorbent member 23 in the skin-facing surface of the topsheet 21. Thus, the leak-proof cuffs 26 are formed so that one end of the sheet 27 stands up as the free end, with the cuff assembly fixing part 291 as a proximal end, when the contraction force of the cuff forming elastic member 28 acts. In this manner, the cuff assembly fixing part 291 of the leak-proof cuffs 26 is disposed on the skin-facing surface of the topsheet 21 and is disposed outward in the lateral direction Y than the side edge along the longitudinal direction X of the absorbent member 23. The diaper 1 illustrated in Fig. 7 brings effects similar to those of the diaper 1 illustrated in Figs. 1 to 5.

[0066] Although the present invention has been demonstrated based on some embodiments thereof, the present invention is not limited to these embodiments and can be appropriately modified.

For example, in the above-described diaper 1, as illustrated in Fig. 2, the sweat-absorbent sheet 10 is provided in each of the front portion F and the rear portion R, but the sweat-absorbent sheet 10 may be provided at least in the rear portion R. [0067] Further, in the above-described diaper I, as illustrated in Fig. 5, the folded part 3 I E of the outer sheet 31 is used as a hydrophobic sheet covering the rear end 2R of the absorbent assembly 2, but a separate hydrophobic sheet may be used.

[0068] When the hydrophobic sheet is the folded part 31 E of the outer sheet 31 or a separate sheet, the form of the hydrophobic sheet is not particularly limited. The hydrophobic sheet may be a single-layer structured nonwoven fabric or may be a laminated nonwoven fabric having a laminate structure including a third layer forming a skin-facing surface and a fourth layer forming a non-skin-facing surface that is opposed to the topsheet 21. In the case of the laminated nonwoven fabric, one or more layers may be interposed between the third layer and the fourth layer. In the case of the single-layer structured nonwoven fabric, a second fusion part where the constituent fibers (thermoplastic fibers) are fused together may be provided. In the above-mentioned laminated nonwoven fabric, a second fusion part where respective layers are fused together may be provided. Such second fusion parts can be formed by applying squeezing processing with fusion promoting means for promoting melting of constituent fibers (thermoplastic fibers), such as heat and ultrasonic waves, specifically, for example, heat sealing processing or ultrasonic sealing, on the constituent fibers.

[0069] When the hydrophobic sheet has the second fusion part, from the viewpoint of adhesive property to the sweat-absorbent sheet 10 and the top sheet 21, it is preferable that the second fusion part is disposed on the non-skin-facing surface of the hydrophobic sheet that faces the topsheet 21. The form in which the second fusion part is disposed on the non-skin-facing surface of the hydrophobic sheet includes not only a form in which the second fusion part is only disposed on the non-skin-facing side, of the skin-facing surface and the non-skin-facing surface of the hydrophobic sheet, but also a form in which the second fusion part is disposed on both the skin-facing surface and the non-skin-facing surface. In the case where the second fusion part is disposed on both the skin-facing surface and the non-skin-facing surface, it is preferable that depression depth of the second fusion part is greater on the non-skin-facing side than on the skin-facing side.

[0070] Further, In the diaper 1, as illustrated in Fig. 2, the outer cover 3 has a continuous shape extending over the front portion F, the crotch portion NI, and the rear portion R. Alternatively, the outer cover 3 may be configured to include a front panel and a rear panel as separate members and the absorbent assembly 2 may be fixed over both of these sheet members.

[0071] In addition, the disposable diaper according to the present invention is not limited to the pull-on disposable diaper such as the above-mentioned diaper 1, and can be applied to, for example, open-type disposable diapers.

[0072] Further, the following additional notes are disclosed with respect to the above-mentioned embodiments of the present invention.

[0073] <1> A disposable diaper comprising an absorbent assembly including a topsheet forming a skin-facing surface, and having a longitudinal direction corresponding to a front-back direction of a wearer and a lateral direction that is orthogonal to the longitudinal direction, wherein a waist part disposed at the waist of the wearer when worn is provided, the waist part is segmented into a front portion disposed on the front side of the wearer when worn and a rear portion disposed on the rear side of the wearer when worn, at least the rear portion includes, as sheets constituting the rear portion, a hydrophobic sheet disposed at a rear end portion of the absorbent assembly in the longitudinal direction over the longitudinal direction and disposed on a skin-facing side of the absorbent assembly, and a sweat-absorbent sheet disposed on a skin-facing side of the hydrophobic sheet, and in a region overlapped with the absorbent assembly in the thickness direction, the joining strength of a first joint region in which the sweat-absorbent sheet and the hydrophobic sheet are joined is greater than the joining strength of a second joint region in which the hydrophobic sheet and the topsheet are j oined.

[0074] <2> The disposable diaper as set forth in clause <1>, wherein the inter-fiber distance of the topsheet is greater than the inter-fiber distance of the sweat-absorbent sheet. <3>

The disposable diaper as set forth in clause <1> or <2>, wherein a skin-facing surface of the topsheet has an uneven shape. <4>

The disposable diaper as set forth in any one of clauses <1> to <3>, wherein an inner end of the sweat-absorbent sheet in the longitudinal direction is located at the same position as an inner end of the hydrophobic sheet in the longitudinal direction or located outward in the longitudinal direction than the inner end of the hydrophobic sheet. <5>

The disposable diaper as set forth in any one of clauses I to 4, wherein an inner end in the longitudinal direction of the first joint region is located at the same position as an inner end in the longitudinal direction of the second joint region or located inward than the inner end of the second joint region. <6>

The disposable diaper as set forth in any one of clauses to <5>, wherein a stretchable region constituted by an elastic member disposed in stretched state in the lateral direction is formed in the rear portion, and in the rear portion, a region located at the same position in the longitudinal direction as a region where the hydrophobic sheet and the topsheet are overlapped in the thickness direction is segmented into a central region where the absorbent assembly is positioned and a pair of side regions positioned outward in the lateral direction from respective side edges along the longitudinal direction of the absorbent assembly, and the central region is lower in extension stress in the lateral direction compared with each side. <7>

The disposable diaper as set forth in clause <6>, wherein the ratio of the extension stress in the lateral direction in each side region to the extension stress in the lateral direction in the central region (each side region /central region) is preferably not less than 1.2, more preferably not less than 1.5 and is preferably not greater than 4.0, more preferably not greater than 3.5. <8>

The disposable diaper as set forth in clause <6> or <7>, wherein the extension stress in the lateral direction in the central region is preferably not less than 5 cN/mm, more preferably not less than 7.5 cN/mm, and is preferably not greater than 25 cN/mm, more preferably not greater than 20 cN/mm. <9>

The disposable diaper as set forth in any one of clauses <6> to <8>, wherein the extension stress in the lateral direction in each side region is preferably not less than 2 cN/mm, more preferably not less than 3 cN/mm, and is preferably not greater than 15 cN/mm, more preferably not greater than 12 cN/mm1.5.

[0075] <10> The disposable diaper as set forth in any one of clauses <1> to <9>, wherein the absorbent assembly has leak-proof cuffs on both sides along the longitudinal direction on the skin-facing surface of the absorbent assembly, and the joining strength of the cuff joint region between the leak-proof cuff and the hydrophobic sheet is greater than the joining strength of the second joint region. <11>

The disposable diaper as set forth in clause <10>, wherein the joining strength of the cuff joint region is preferably not less than 1.5 times, more preferably not less than 2.0 times, and not greater than 7.5 times, more preferably not greater than 5.0 times the joining strength of the second joint region. <12>

The disposable diaper as set forth in clause <10> or <11>, wherein the joining strength of the cuff joint region is preferably not less than 1.5 N/25 mm, more preferably not less than 2.0 N/25 mm, and is preferably not greater than 15 N/25 mm, more preferably not greater than 10 N/25 mm. <13>

The disposable diaper as set forth in clause <10>, wherein a free-end fixing part via which the free end of the leak-proof cuff is fixed on the skin-facing surface of the topsheet is provided in the rear end portion of the absorbent assembly, and the hydrophobic sheet extends to reach a region located inward in the longitudinal direction than the free-end fixing part disposed at an innermost end of the leak-proof cuff in the lateral direction and is joined with the leak-proof cuff [0076] <14> The disposable diaper as set forth in any one of clauses <1> to <13>, wherein the sweat-absorbent sheet has a skin-facing side that is lower in hydrophilicity compared with a non-skin-facing side. <15>

The disposable diaper as set forth in any one of clauses to <14>, wherein an outer cover that comprises a laminated body constituted by an outer sheet that forms a nonskin-facing surface in a worn state and an inner sheet disposed to be opposed to a skin-facing surface of the outer sheet and is disposed on a non-skin-facing surface of the absorbent assembly is provided, and in the front portion and the rear portion, the outer sheet has a hydrophobic folded part extending from an end edge of the inner sheet in the longitudinal direction and folded on a skin-facing side of the inner sheet, and the hydrophobic sheet that covers the rear end portion of the absorbent assembly is constituted by the folded part of the outer sheet. <16>

The disposable diaper as set forth in clause <15>, wherein the inner end of the sweat-absorbent sheet in the longitudinal direction is positioned outward in the longitudinal direction than an inner end of the folded part.

[0077] <17> The disposable diaper as set forth in clause <15> or <16>, wherein the inner end in the longitudinal direction of the first joint region in which the sweat-absorbent sheet and the folded part are joined is positioned inward in the longitudinal direction than the inner end in the longitudinal direction of the second joint region in which the folded part and the top sheet are joined. <18>

The disposable diaper as set forth in any one of clauses <1> to <17>, wherein the absorbent assembly comprises a liquid-retentive absorbent member, and in the rear portion, the sweat-absorbent sheet is disposed so as to straddle both of an absorbent member arrangement region in which the absorbent member is disposed and an absorbent member-less region in which the absorbent member is not disposed.

The disposable diaper as set forth in any one of clauses <1> to <18>, wherein the joining strength of the first joint region i s preferably not less than 1.5 times, more preferably not less than 2.0 times, and not greater than 7.5 times, more preferably not greater than 5.0 times the joining strength of the second joint region. <20>

The disposable diaper as set forth in any one of clauses to <19>, wherein the joining strength of the first joint region is preferably not less than 1.5 N/25 mm, more preferably not less than 2.0 N/25 mm, and is preferably not greater than 25 N/25 mm, more preferably not greater than 20 N/25 mm. <21>

The disposable diaper as set forth in any one of clauses <1> to <20>, wherein the joining strength of the second joint region is preferably not less than 0.5 N/25 mm, more preferably not less than 1.0 N/25 mm, and is preferably not greater than 3.0 N/25 mm, more preferably not greater than 2.5 N/25 mm, and is not less than 0.5 N/25 mm and not greater than 3.0 N/25 mm.

[0078] <22> The disposable diaper as set forth in any one of clauses <1> to <21>, wherein the difference between the inter-fiber distance of the topsheet and the inter-fiber distance of the sweat-absorbent sheet is preferably not less than 20 jun, more preferably not less than 30 pm and is preferably not greater than 100 pm, more preferably not greater than 90 pm, as a value obtainable by subtracting the latter from the former. <23>

The disposable diaper as set forth in any one of clauses <1> to <22>, wherein the inter-fiber distance of the topsheet is preferably not greater than 250pm, more preferably not greater than 150 pm, and is preferably not less than 50 pm, more preferably not less than 70 pm. <24>

The disposable diaper as set forth in any one of clauses <1> to <23>, wherein the inter-fiber distance of the sweat-absorbent sheet is preferably not greater than 150 p.m, more preferably not greater than 90 pm, and is preferably not less than 5 pm, more preferably not less than 10 pm. <25>

The disposable diaper as set forth in any one of clauses to <24>, wherein the topsheet comprises a plurality of projections disposed in a scattered manner in the whole area of a skin-facing surface thereof, and the periphery of each projection is depressed <26> The disposable diaper as set forth in any one of clauses to <25>, wherein the contact angle between a skin-facing surface of the sweat-absorbent sheet and ion-exchanged water is preferably not less than 90°, more preferably not less than 100°, and is preferably not greater than 150°, more preferably not greater than 140°. <27>

The disposable diaper as set forth in any one of clauses <1> to <26>, wherein the contact angle between a non-skin-facing surface of the sweat-absorbent sheet and ion-exchanged water is preferably smaller than 90°, more preferably not greater than 88°, and even more preferably not greater than 85°, and is preferably not less than 35°, more preferably not less than 40° . <28> The disposable diaper as set forth in any one of clauses <1> to <27>, wherein the sweat-absorbent sheet has a fusion part where thermoplastic fibers are fused together, and the fusion part is disposed on the skin-facing surface of the sweat-absorbent sheet. <29>

The disposable diaper as set forth in any one of clauses to <28>, wherein the hydrophobic sheet has a second fusion part where thermoplastic fibers are fused together, and the second fusion part is disposed on a non-skin-facing surface of the hydrophobic sheet. <30>

The disposable diaper as set forth in any one of clauses <1> to <29>, wherein the absorbent assembly has a liquid-retentive absorbent core, and the sweat-absorbent sheet and the absorbent core are overlapped with each other in a region where the sweat-absorbent sheet and the absorbent assembly are overlapped in the thickness direction. <31>

The disposable diaper as set forth in any one of clauses <1> to <30>, wherein the thickness of the topsheet is greater than the thickness of the sweat-absorbent sheet. <32>

The disposable diaper as set forth in any one of clauses <1> to <31>, wherein the difference between the thickness of the topsheet and the thickness of the sweat-absorbent sheet is preferably not less than 0.8 mm, more preferably not less than 1 mm, and is preferably not greater than 4 mm, more preferably not greater than 3 mm, as a value obtainable by subtracting the latter from the former. <33>

The disposable diaper as set forth in any one of clauses to <32>, wherein the thickness of the topsheet is preferably not greater than 5 mm, more preferably not greater than 3 mm, and is not less than 0.2 mm, more preferably not less than 0.5 mm. <34>

The disposable diaper as set forth in any one of clauses <1> to <33>, wherein the thickness of the sweat-absorbent sheet is preferably not greater than 2 mm, more preferably not greater than 1 mm, and is preferably not less than 0.1 mm, more preferably not less than 0.2 mm. <35>

The disposable diaper as set forth in any one of clauses to <34>, wherein the fiber diameter of constituent fibers of the topsheet is greater than the fiber diameter of constituent fibers of the sweat-absorbent sheet. <36>

The disposable diaper as set forth in any one of clauses <1> to <35>, wherein the difference between the fiber diameter of constituent fibers of the topsheet and the fiber diameter of constituent fibers of the sweat-absorbent sheet is preferably not less than 2 p.m, more preferably not less than 3 um, and is preferably not greater than 10 itm, more preferably not greater than 8 Jim, as a value obtainable by subtracting the latter from the former. <37>

The disposable diaper as set forth in any one of clauses <1> to <36>, wherein the fiber diameter of constituent fibers of the topsheet is preferably not greater than 25 tn, more preferably not greater than 20 um, and is preferably not less than 8 um, more preferably not less than 10 um. <38>

The disposable diaper as set forth in any one of clauses to <37>, wherein the fiber diameter of constituent fibers of the sweat-absorbent sheet is preferably not greater than 20 p.m, more preferably not greater than 18 p.m, and is preferably not less than 1 um, more preferably not less than 5 um.

Industrial Applicability

[0079] The disposable diaper according to the present invention can prevent the sweat-absorbent sheet from being turned over during wearing and can suppress skin troubles resulting from sweat.