WO2013018846A1

WO2013018846A1 - Disposable diaper

Info

Publication number: WO2013018846A1
Application number: PCT/JP2012/069640
Authority: WO
Inventors: Hironao Minato; Ryugo OHASHI
Original assignee: Unicharm Corp
Current assignee: Unicharm Corp
Priority date: 2011-07-29
Filing date: 2012-07-26
Publication date: 2013-02-07
Anticipated expiration: 2014-01-29
Also published as: JP5709685B2; JP2013027674A; CN103687578B; TW201318611A; AU2012290996A1; TWI533858B; AU2012290996B2; CN103687578A

Abstract

Provided is a disposable diaper that allows excreted urine to smoothly move to an absorber and allows a user to wear the product in a state in which it is flexibly fitted to the user's body. A disposable diaper comprises a top sheet, a back sheet, an absorber, and a hydrophilic and liquid-permeable absorptive and diffusive sheet interposed between the top sheet and the absorber, in which the top sheet has ridges and furrows, the ridges having a higher weight per unit area than the furrows; the absorptive and diffusive sheet is provided on a part of a region in a surface direction of the absorber; and when a front-back direction length of the absorber is L₀, in the disposable diaper for a male, a front end of the absorptive and diffusive sheet is in a position of 0.0L₀ to 0.10L₀ from the front end of the absorber and a rear end of the absorptive and diffusive sheet is in a position of 0.50L₀ to 0.85L₀ from the front end of the absorber, whereas, in the disposable diaper for a female, the front end of the absorptive and diffusive sheet is in a position of 0.2L₀ to 0.35L₀ from the front end of the absorber and the rear end of the absorptive and diffusive sheet is in a position of 0.7L₀ to 1.0L₀ from the front end of the absorber.

Description

DESCRIPTION

DISPOSABLE DIAPER

TECHNICAL FIELD

The present invention relates to a disposable

diaper.

BACKGROUND ART

An absorbent article comprising a liquid-permeable top sheet having ridges and furrows on a surface thereof, a liquid-impermeable back sheet, an absorber interposed between the top sheet and the back sheet, and an^"

absorptive and diffusive sheet interposed between the top sheet and the absorber is known. See JP 2009-000173 A.

SUMMARY OF THE INVENTION TECHNICAL PROBLEM

In the absorbent, article described in JP 2009-000173 A, the absorptive and diffusive sheet is provided on an entire surface of the absorbent article. In the case of a disposable diaper provided with such an absorptive and diffusive sheet, due to the presence, of the sheet on a part of the disposable diaper other than at a region frequently absorbing urine, the product cannot be easily bent, which thus can increase a wearer's discomfort when wearing it. It is an object of the present invention to provide a disposable diaper that allows excreted urine to_. smoothly move to the absorber and allows a wearer to wear the product in a state in which it is flexibly fitted to the wearer's body.

SOLUTION TO PROBLEM

To solve the problem, in the present invention, an absorptive and diffusive sheet is arranged only in a position where urine is excreted. The position of the absorptive and diffusive sheet arranged is different between the products for a male and female, since the position of urination is different between a male and female .

Specifically, the present invention relates to a disposable diaper comprising a liquid-permeable top sheet made of a nonwoven fabric, a liquid-impermeable back sheet, and an absorber interposed between the top sheet and the back sheet, wherein

the disposable diaper further comprises a

hydrophilic and liquid-permeable absorptive and diffusive sheet between the top sheet and the absorber;

the top sheet has a plurality of ridges and furrows extending in parallel in a front-back direction of the disposable diaper on the surface of the top sheet

contacting a wearer's skin, the surface of the top sheet opposite to the surface contacting the wearer's skin being flat;

the ridges have a higher weight per unit area than the furrows;

the absorptive and diffusive sheet is provided only on a part of the absorber corresponding to an absorption zone, which absorption zone includes and surrounds the position of urination of the wearer; and

where the length of the absorber in the front-back direction is L₀, in the case of a disposable diaper for a male, the front end of the absorptive and diffusive sheet is positioned 0.0L₀ to 0.10L₀ from the front end of the absorber and the rear end of the absorptive and diffusive sheet is positioned 0.50L₀ to 0.85L₀ from the front end of the absorber; and in the case of a disposable diaper for a female, the front end of the absorptive and diffusive sheet is positioned 0.20L₀ to 0.35L₀ from the front end of the absorber and the rear end of the absorptive and diffusive sheet positioned 0.70L₀ to 1.0L₀ from the front end of the absorber.

ADVANTAGEOUS EFFECTS OF INVENTION A disposable diaper according to the present

invention allows excreted urine to smoothly move to the absorber and allows the wearer to wear the product in a state in which it is flexibly fitted on the wearer's body.

BRIEF DESCRIPTION OF DRAWINGS

Fig. 1 is a plan view of a disposable diaper

according to a first embodiment of the present invention.

Fig. 2 is a plan view of a disposable diaper

according to a second embodiment of the present

invention .

Fig. 3 is a cross-sectional view of the disposable diaper according to the first and the second embodiments of the present invention.

Fig. 4 is a view illustrating a method for forming a top sheet having a plurality of ridges and furrows extending in parallel in a front-back direction.

Fig. 5 is a view showing a cross section in a cross direction of the top sheet where the ridges and the furrows have been formed.

DESCRIPTION OF EMBODIMENTS

The present invention is a disposable diaper

comprising a liquid-permeable top sheet made of a

nonwoven fabric, a liquid-impermeable back sheet, and an absorber interposed between the top sheet and the back sheet, wherein

the disposable diaper further comprises a

contacting a wearer's skin, the surface of the top sheet opposite to the surface contacting the wearer's skin being flat; the ridges have a higher weight per unit area than the furrows;

where the length of the absorber in the front-back direction is L₀, in the case of a disposable diaper for a male, the front end of the absorptive and diffusive sheet is positioned 0 0L₀ to 0.10L₀ from the front end of the absorber and the rear end of the absorptive and diffusive sheet is positioned 0.50L₀ to 0.85Lo from the front end of the absorber; and in the case of a disposable diaper for a female, the front end of the absorptive and diffusive sheet is positioned 0.20L₀ to 0.35Lo from the front end of the absorber and the rear end of the absorptive and diffusive sheet is positioned 0.70L₀ to 1.0L₀ from the front end of the absorber.

Preferably, the absorptive and diffusive sheet has a density larger than the density of the furrows of the top sheet and smaller than the density of the ridges of the top sheet.

Preferably, a leg-surrounding elastic member is provided on both side portions of the disposable diaper, and when the disposable diaper is for a male, the front end of the absorptive and diffusive sheet is located further forward^' than the front end of the leg-surrounding elastic member, whereas when the disposable diaper is for a female, the front end of the absorptive and diffusive sheet is located further rearward than the front end of the leg-surrounding elastic member.

Preferably, a fastener target tape is provided on the front waistline region of the disposable diaper, and when the disposable diaper is for a male, a part of the absorptive and diffusive sheet overlaps the target tape, whereas when the disposable diaper is for a female, the absorptive and diffusive sheet does not overlap the target tape.

Preferably, an opening hole or a portion having a relatively small density is present in the furrows of the top sheet.

The present invention also includes the following two embodiments.

[1] A disposable diaper for male, comprising a liquid-permeable top sheet made of a nonwoven fabric, a liquid-impermeable back sheet, and an absorber interposed between the top sheet and the back sheet, wherein

the disposable diaper further comprises a

the ridges have a higher weight per unit area than the furrows;

where the length of the absorber in the front-back direction is Lo, the front end of the absorptive and diffusive sheet is positioned 0.0L₀ to 0.10L₀ from the front end of the absorber and the rear end of the

absorptive and diffusive sheet is positioned of 0.50L₀ to

0.85L₀ from the front end of the absorber;

a leg-surrounding elastic member is provided on both side portions of the disposable diaper, and the front end of the absorptive and diffusive sheet is located further forward than the front end of the leg-surrounding elastic member; and

a fastener target tape is provided on the front waistline region of the disposable diaper, and a part of the absorptive and diffusive sheet overlaps the target tape .

[2] A disposable diaper for a female comprising a liquid-permeable top sheet made of a nonwoven fabric, a liquid-impermeable back sheet, and an absorber interposed between the top sheet and the back sheet, wherein

the disposable diaper further comprises a

the ridges have a higher weight per unit area than the furrows;

where the length of the absorber in the front-back direction is L₀, the front end of the absorptive and diffusive sheet is positioned 0.20L₀ to 0.35L₀ from the front end of the absorber and the rear end of the

absorptive and diffusive sheet is positioned .0.70L₀ to

1.0L₀ from the front end of the absorber;

a leg-surrounding elastic member is provided on both side portions of the disposable diaper, and the front end of the absorptive and diffusive sheet is located further rearward than a front end of the leg-surrounding elastic member;

a fastener target tape is provided on the front waistline region of the disposable diaper, and the absorptive and diffusive sheet does not overlap the target tape. Hereinafter, a disposable diaper according to the present invention will be described with reference to the drawings. The present invention is not restricted to the embodiments shown in the drawings.

Fig. 1 is a plan view of a disposable diaper

according to a first embodiment of the present invention; Fig. 2 is a plan view of a disposable diaper according to a second embodiment of the present invention; and Fig. 3 is a schematic cross-sectional view of a cross section taken along line A-A of Fig. 1 and a cross section taken along line B-B of Fig. 2. The disposable diaper of the first embodiment is a disposable diaper for male, and the disposable diaper of the second embodiment is a

disposable diaper for female.

A disposable diaper 1 is provided with a chassis 20 having a shape whereby both right and left side edges are curved inward in a concave form; a flap portion 30 being arranged on each of the right and left side portions of the chassis 20 and having both side edges of the same shape as the side edges of the chassis 20; a back sheet 40 arranged on a center region in the cross direction of the chassis 20; an absorber 50 arranged above the back sheet 40; and a top sheet 60 arranged above the absorber 50. The disposable diaper 1 is composed of a front waistline region 12 covering the lower abdominal region of a wearer when the diaper is worn, a crotch region 14 covering the crotch area of the wearer when worn, and a rear waistline region 16 covering the buttocks of the wearer when worn. In Figs. 1 and 2, a longitudinal direction (axis y) of the disposable diaper 1 is the front-back direction thereof and a transverse direction (axis x) orthogonal to the longitudinal direction.

Preferably, between the chassis 20 and the flap portion 30 there is provided, near end portions thereof in the transverse direction, an elastic member 70

extending in the longitudinal direction of the disposable diaper 1. Additionally, near an end portion of the flap portion 30 on the center side of the disposable diaper 1 there is provided an elastic member 80 extending in the longitudinal direction of the disposable diaper 1.

The disposable diaper according to the present invention may be an open-type disposable diaper or an underpants-type disposable diaper. The disposable diapers shown in Figs. 1 and 2 are of the open type.;- In the case of the open-type disposable diaper, usually, fastener tapes 160, 160 are arranged at both right and left ends of the rear waistline portion of the chassis

20, and a fastener target tape 150 is arranged at the front waistline portion of the chassis 20. In one embodiment, on a surface of the fastener target tape 150 there is provided a loop material and on leading ends of the fastener tapes 160 there is provided a hook material, so that the loop material of the fastener target tape 150 and the hook material of the fastener tape 160, 160 form a hook and loop fastener. When the fastener tapes 160, 160 are bonded to the fastener target tape 150, openings around the wearer's legs are formed by both side edges of the chassis 20 inwardly curved in the concave form on the right and left thereof, the flap portion 30 form.

The chassis 20 forms the outline of the main body of the disposable diaper 1. To prevent a diaper wearer from feeling hot and humid when wearing it, the chassis 20 is preferably made of an air-permeable nonwoven fabric, plastic film, or the like. The flap portion 30 covers a wearer's leg-surrounding region, the lower abdominal portion and both sides of the buttock of the wearer. The flap portion 30 is preferably made of a hydrophobic nonwoven fabric. The elastic member 70 provided between the chassis 20 and the flap portion 30 improves leg- surrounding fittability in the disposable diaper 1.

Additionally, with the contractile force of the elastic member 80 provided near the end portion of the flap portion 30 on the center side of the disposal diaper 1, a center side of the flap portion 30 stands up to form a leakage prevention wall 34 for preventing urine or loose stool from leaking out from a part in a transverse direction of the crotch region 14 of the disposable diaper 1. Examples of the material of the elastic members 70 and 80 include elastic fibers, such as natural rubber, synthetic rubber, and spandex.

The back sheet 40 is a liquid-impermeable sheet that does not allow urine to pass through it and is provided to prevent the leakage of excreted urine. Examples of suitable materials for the back sheet 40 include a waterproof nonwoven fabric, a plastic film made of polyethylene or the like, and a composite material of a nonwoven fabric and a plastic film.

The absorber 50 absorbs and retains urine of the diaper wearer. For example, the absorber 50 may be composed mainly of an absorbing member 51, such as a pulverized pulp, a super absorbent polymer, or a

hydrophilic sheet, and covering sheets 52, 53 for

enveloping the absorbing member 51, such as tissue paper or a nonwoven fabric subjected to hydrophilic treatment.

The covering sheets 52, 53 comprise an upper covering sheet 52 for covering a surface of the absorbing member 51 facing the top sheet 60 and a lower covering sheet 53 for covering the other surfaces of the absorbing member 51. The covering sheets 52, 53 may be bonded to the absorbing member 51 with an adhesive such as a hot melt adhesive. The adhesive is applied to the absorbing member 51 or the covering sheets 52, 53 by spiral

coating, curtain coating, or the like.

The top sheet 60 is a liquid-permeable nonwoven fabric that quickly absorbs the wearer's urine to move it to the absorber 50. Hereinbelow, a surface of the top sheet 60 contacting with a wearer's skin is referred to as "skin-contacting surface", and a surface of the top sheet 60 opposite to the surface thereof contacting with the wearer's skin is referred to as "skin-noncontacting surface". The top sheet 60 has a plurality of ridges 61 and furrows 62 extending in parallel in the front-back direction of the disposable diaper on the skin-contacting surface. The plurality of ridges 61 and the plurality of furrows 62 are alternately arranged in the transverse direction. The skin-noncontacting surface of the top sheet is flat.

The ridges have a higher weight per unit area than the furrows. The weight per unit area of the ridges is preferably 15 to 50 g/m², more preferably 20 to 40 g/m², and still more preferably 28 to 35 g/m². The weight per unit area of the furrows is preferably 5 to 20 g/m², more preferably 8 to 18 g/m², and still more preferably 10 to 15 g/m². When the top sheet has a total weight, per unit area of about 25 g/m², preferably, the weight per unit area of the ridges is 28 to 32 g/m² and the weight per unit area of the furrows is 10 to 15 g/m².

Preferably, an opening hole or a portion having a small density is present in the furrows 62 of the top sheet. Herein, the term "small density" means a density of 0.015 g/cm³ or lower. By arranging an opening hole or a small-density portion in the furrows of the top sheet, urine can easily pass through the furrows 62 of the top sheet when the urine is expelled with force.

The distance between the peaks of adjacent ridges 61 is preferably 1 to 10 mm, more preferably 2 to 8 mm, still more preferably 3 to 5 mm, and most typically, approximately 4 mm. The ridges 61 have a width of preferably 1 to 10 mm, more preferably 2 to 5 mm, and still more preferably 3 to 4 mm. The furrows 62 have a width of preferably 0.5 to 20 mm, more preferably 1.0 to

10 mm, and still more preferably 2 to 5 mm. Most

typically, the width of the ridges 61 is approximately 3.0 mm. Most typically, the width of the furrows 62 is approximately 1.0 mm.

The nonwoven fabric used for the top sheet 60

preferably includes fibers in which intersections between the fibers are heat-sealed. Such fibers are, for example, made of a thermoplastic polymer material.

Examples of the fibers include polyolefins such as polyethylene and polypropylene, polyesters such as polyethylene terephthalate, and polyamide.

Alternatively, as such fibers, core/sheath type and side- by-side type composite fibers made of combinations of a plurality of thermoplastic polymer materials may be used.

Normally, in a diaper having a top sheet made of a nonwoven fabric having a uniform weight per unit area, when urination occurs at a position other than a position where the absorptive and diffusive sheet is arranged or urine flowing on the surface is absorbed, the permeation of urine into the absorber is delayed and it takes time to absorb the urine on the top sheet, resulting in leakage of urine. In contrast, in the disposable diaper according to the present invention, the top sheet has the ridges and the furrows and the weight per unit area of the furrows is lower and therefore, urine on the top sheet can quickly move to an underlayer through the furrows, allowing the prevention of leakage of urine flowing on the surface of the top sheet.

Next, with reference to Fig. 4, a description will be given of an example of a method for producing the top sheet 60 having the plurality of ridges 61 and the plurality of furrows 62. Fig. 4 is a view illustrating a process for forming ridges and furrows on a web formed to produce a nonwoven fabric, and Fig. 5 is a view showing a cross section in a cross direction (CD) of the web where the ridges and the furrows have been formed. A web 210 formed by a web forming means such as a carding machine is conveyed to a suction drum 220. Then, from nozzles of an ejection section 230, a heated fluid flow 231 is sprayed to push a part of the web 210 aside, thereby forming ridges 211 and furrows 212 on the web 210.

Fibers pushed aside in the cross direction (CD)

orthogonal to a machine direction (MD) as a travel direction of the web 210 by the fluid flow 231 gather. to the ridges 211. Accordingly, fibers of a region

corresponding to the furrows 212 are accumulated at the ridges 211, so that the weight per unit area of the ridges 211 becomes higher. In addition, the fluid flow 231 blows off the fibers in the cross direction (CD) , so that the weight per unit area of the furrows 212 becomes lower.

The fluid flow 231 ejected from the ejection section 230 may be a gas such as air or water vapor, or a liquid such as water. Alternatively, the fluid flow 231 may be an aerosol in which solid or liquid microparticles are contained in a gas.

The disposable diaper 1 has an absorptive and diffusive sheet 90 between the top sheet 60 and the absorber 50. The absorptive and diffusive sheet 90 is provided to quickly absorb and diffuse the wearer's urine expelled on the top sheet 60. The absorptive and

diffusive sheet 90. is made of a hydrophilic and liquid- permeable material. For example, a woven fabric, a nonwoven fabric, or the like made of hydrophilic and liquid-permeable fibers can be used as the absorptive and diffusive sheet 90. The absorptive and diffusive sheet 90 is preferably a nonwoven fabric made of hydrophilic and liquid-permeable fibers.

The absorptive and diffusive sheet 90 is provided on a part of a region in a surface direction of the absorber 50, as shown in Figs. 1 and 2. The absorptive and diffusive sheet is provided only on the part of the absorber 50 corresponding to an absorption zone, which absorption zone includes and surrounds the position of urination of the wearer.

In the case of the disposable diaper for a male, where a front-back direction length of the absorber is L₀, the front end 91 of the absorptive and diffusive sheet is positioned 0.0L₀ to 0.10L₀ from the front end 54 of the absorber, and preferably 0.07L₀ to 0.095L₀ from the front end 54 of the absorber. The rear end 92 of the absorptive and diffusive sheet is positioned 0.50Lo to 0.85L₀ from the front end 54 of the absorber.

In a case of the disposable diaper for a female, the front end 91 of the absorptive and diffusive sheet is positioned 0.20Lo to 0.35L₀ from the front end 54 of the absorber, and preferably 0.25L₀ to 0.30L₀ from the front end 54 of the absorber. The rear end 92 of the

absorptive and diffusive sheet is positioned 0.70L₀ to l.OLo from the front end 54 of the absorber, and

preferably 0.75Lo to 0.80L₀ from the front end 54 of the absorber .

The absorptive and diffusive sheet 90 is provided on a region (absorption zone) including a position

(urination point) corresponding to an excretion outlet of urine of the wearer and its surrounding area, e.g., in the case of a diaper for a male, on a region close to the front waistline region 12 in the surface direction region of the absorber 50. The region of the absorption zone is different between the disposable diaper for a male and that for a female, so that the region for providing the absorptive and diffusive sheet 90 is also different therebetween. Specifically, the region of the absorptive and diffusive sheet 90 in the disposable diaper for a male is close to the front waistline region 12, as compared to the region of the absorptive and diffusive sheet 90 in the disposable diaper for a female.

When the leg-surrounding elastic member 70 is provided on both side portions of the disposable diaper, in the disposable diaper for male, the front end 91 of the absorptive and diffusive sheet 90 is located further forward than a front end 71 of the leg-surrounding elastic member 70, whereas in the disposable diaper for female, the front end 91 of the absorptive and diffusive sheet 90 is located further rearward than the front end 71 of the leg-surrounding elastic member 70. In the case of a male, urine tends to be excreted with force

forwardly. Accordingly, preferably, the absorptive and diffusive sheet 90 is present also on a forward part where stress of the leg-surrounding elastic member 70 is not applied.

When the fastener target tape 150 is arranged on the front waistline region of the disposable diaper, in a disposable diaper for a male, at least part of the absorptive and diffusive sheet 90 overlaps the target tape 150, whereas in the disposable diaper for a female, the absorptive and diffusive sheet 90 does not overlap the target tape 150. This can create an effect in which urine is absorbed in a part near the center of the diaper and is permeated into the absorber, thereby preventing the urine from staying near the target tape and leaking out .

In the disposable diaper according to the present invention, by arranging the absorptive and diffusive sheet in the urination position, the absorptive and diffusive sheet temporarily absorbs a large amount of urine immediately after urination. This can prevent urine from flowing, on the surface of the top sheet and leaking out. Then, the urine absorbed in the absorptive and diffusive sheet moves gradually to the absorber to be absorbed therein.

In the disposable diaper according to the present invention, through the combination of the top sheet having ridges and the furrows and the absorptive and diffusive sheet being arranged at a urination position specific to either a male or a female, urine can

efficiently permeate into the absorber through the absorptive and diffusive sheet; in addition, urine permeation at a place outside the area of arrangement of the absorptive and diffusive sheet is improved, so that urinary leakage does not easily occur. The disposable diaper of the present invention can be worn in a state in which the product is flexibly fitted on the wearer's body, since the absorptive and diffusive sheet is not present on any place other than the region where urine is frequently absorbed.

Preferably, the absorptive and diffusive sheet has a density larger than the density of the furrows of the top sheet and smaller than the density of the ridges of the top sheet. In other words, preferably, the density is larger in the order of the furrows of the top sheet, the absorptive and diffusive sheet, and the ridges of the top sheet. Herein, the density means the weight per unit volume. By setting a magnitude relationship of density as above, a large amount of urine can be dropped and hardly return to the surface. More specifically, when urine is expelled with force, the urine stays first in the furrows of the top sheet. Since the density of the absorptive and diffusive sheet is larger than the density of the furrows of the top sheet, the urine staying in the furrows of the top sheet quickly moves to the absorptive and diffusive sheet due to the principle of capillary action and absorbed therein. The urine absorbed in the absorptive and diffusive sheet is retained in the

absorptive and diffusive sheet. After that, the urine is diffused in the surface direction and moved to the absorber to be absorbed therein. When the urine absorbed tries to return to the surface, it is held by the ridges of the top sheet having the larger density, so that liquid return hardly occurs.

The density of the absorptive and diffusive sheet is preferably 0.015 to 0.05 g/cm³, more preferably 0.017 to 0.04 g/cm³, and still more preferably 0.02 to 0.03 g/cm³. The density of the ridges of the top sheet is preferably 0.015 to 0.06 g/cm³, more preferably 0.015 to 0.03 g/cm³, and still more preferably 0.015 to 0.02 g/cm³. The density of the furrows of the top sheet is preferably 0.010 to 0.02 g/cm³, and more preferably 0.015 to 0.02 g/cm³.

The weight per unit area of the absorptive and diffusive sheet is preferably 20 to 60 g/m², more

preferably 25 to 50 g/m², still more preferably 30 to 40 g/m², and most typically approximately 40 g/m².

The absorptive and diffusive sheet 90 is preferably made of a material having a faster urine absorption rate than the absorbing member 51. By forming the absorptive and diffusive sheet 90 using a material having a faster absorption rate, when urine is expelled with force, the absorptive and diffusive sheet 90 can quickly absorb a large amount of urine. Preferably, the absorptive and diffusive sheet 90 is made of a material that can

reversibly absorb and discharge urine. By forming the absorptive and diffusive sheet 90 using a reversibly absorbable and dischargeable material, urine once

absorbed in the absorptive and diffusive sheet then gradually moves to the absorber to be absorbed therein. Preferably, the absorbing member 51 is made of a material that irreversibly absorbs urine and does not easily discharge the urine once absorbed, or includes such a material. In addition, preferably, the absorbing member 51 is made of a material having a large absorption capacity, although the absorption capacity of the

absorptive and diffusive sheet 90 may be smaller than that of the absorbing member 51. Examples of such a material may be nonwoven fabrics such as through-air nonwoven fabrics having a single or plural layer

structure, which can be used as the absorptive and diffusive sheet 90. Examples of fibers forming the nonwoven fabrics include monofilaments of polypropylene (PP), or composite fabrics made of polyethylene

( PE) /polyethylene terephthalate (PET), or core/sheath type and side-by-side type composite fibers made of

PP/PE. One kind can be used alone or a plurality can be used in combination. The fibers or nonwoven fabrics can be provided with hydrophilic properties by applying a hydrophilic oil agent to their surface or kneading a hydrophilizing agent into their surface.

The absorptive and diffusive sheet 90 may be bonded with the top sheet 60 and the absorber 50 using an adhesive such as a hot-melt type adhesive. The adhesive may be applied to the absorptive and diffusive sheet 90, the top sheet 60, or the absorber 50 by spiral coating, curtain coating, or the like.

As a method for manufacturing a disposable diaper of the present invention, a conventional method is

applicable. For example, a disposable diaper can be manufactured by providing a liquid-permeable top sheet, a liquid-impermeable back sheet, an absorber, and an absorptive and diffusive sheet in advance, placing a liquid-impermeable back sheet on a table, and then stacking an absorber, an absorptive and diffusive sheet, and a liquid-permeable top sheet in this order on the liquid-impermeable back sheet.

Hereinafter, some advantageous functional effects of particular embodiments of the present invention will be described. Upon urination on the top sheet, liquid permeation is hardly inhibited and the urine can be quickly moved to the absorber, since the weight per unit area of the furrows is lower and thus the number of fibers per unit area is less. Furthermore, by combining with the absorptive and diffusive sheet arranged

differently by gender, urine expelled in a position different between a male and female can be more quickly moved to the absorber. In this case, by effectively giving a holding force of crotch gather and a fastening force of the waist tape to the abdominal end region of the product, a clearance between the absorptive and diffusive sheet and the skin is reduced, thereby allowing the urine to be effectively moved to the absorber.

According to the present invention, when urine flows on the diaper surface, such as in the sleeping postures of a male and female whose urination position and absorption position are different, urinary absorption is improved and thus urinary leakage is reduced.

Preferably, the absorptive and diffusive sheet 90 is colored. When the absorptive and diffusive sheet 90 is colored with a color other than white, the members of the disposable diaper 1, except for the absorptive and diffusive sheet 90, such as the top sheet 60, are

preferably white. This can appropriately accentuate, on the top sheet 60, the ridges 61 and the furrows 62 on the skin-contacting surface of the top sheet 60 in the region where the absorptive and diffusive sheet 90 is located. Then, the presence of enhanced function of the surface of the top sheet 60 of the disposable diaper 1 can be shown such that the user can immediately understand.

Additionally, the disposable diaper 1 can be provided with a strip-shaped pattern and thus can be excellent in design. Furthermore, after using the disposable diaper 1, the ridges 61 of the top sheet 60 look white and three-dimensional, as compared to the furrows 62 through which the absorptive and diffusive sheet 90 can be seen. Therefore, the user can see that the portion directly in contact with the wearer's skin is white and less dirty, which can give an impression of cleanliness to the user.

Additionally, the absorptive and diffusive sheet 90 is arranged on a part of the region in the surface direction of the absorber 50. Thus, by arranging the absorptive and diffusive sheet 90 on a region such as the absorption zone of the disposable diaper 1, the user can easily recognize the region such as the absorption zone.

Furthermore, the region in the surface direction where the absorptive and diffusive sheet 90 is located is different between the disposable diaper for a male and that for female. This allows the user to easily

recognize the absorption zone different between the disposable diaper for a male and that for female.

Accordingly, the user can effectively recognize the improved absorption function of the diaper, since the colored absorptive and diffusive sheet 90 is

appropriately present near the urination point of a wearer and the presence of the ridges and the furrows near the urination point of the diaper can be easily seen .

The technological scope of the present invention includes each of the disposable diaper for a male and the disposable diaper for a female.

Specifically, the technological scope of the present invention includes a disposable diaper for a male

comprising a liquid-permeable top sheet made of a

nonwoven fabric, a liquid-impermeable back sheet, and an absorber interposed between the top sheet and the back sheet, wherein the disposable diaper for a male further comprises a hydrophilic and liquid-permeable absorptive and diffusive sheet between the top sheet and the

absorber; the top sheet has a plurality of ridges and furrows extending in parallel in a front-back direction of the disposable diaper on a surface contacting a wearer's skin, a surface of the top sheet opposite to the surface contacting the wearer's skin being flat; the ridges have a higher weight per unit area than the furrows; the absorptive and diffusive sheet is provided on a part of a region in a surface direction of the absorber; and when a front-back direction length of the absorber is Lo, a front end of the absorptive and

diffusive sheet is in a position of 0.0L₀ to 0.10L₀ and a rear end of the absorptive and diffusive sheet is in a position of 0.50Lo to 0.85L₀.

Additionally, the technological scope of the present invention also includes a disposable diaper for a female comprising a liquid-permeable top sheet made of a

nonwoven fabric, a liquid-impermeable back sheet, and an absorber interposed between the top sheet and the back sheet, wherein the disposable diaper for a female further comprises a hydrophilic and liquid-permeable absorptive and diffusive sheet between the top sheet and the

absorber; the top sheet has a plurality of ridges and furrows extending in parallel in a front-back direction of the disposable diaper on a surface contacting with a wearer's skin, a surface of the top sheet opposite to the surface contacting with the wearer's skin being flat; the ridges have a higher weight per unit area than the furrows; the absorptive and diffusive sheet is provided on a part of a region in a surface direction of the absorber; and when a front-back direction length of the absorber is L₀, a front end of the absorptive and

diffusive sheet is in a position of 0.2L₀ to 0.35L₀ and a rear end of the absorptive and diffusive sheet is in a position of 0.7L₀ to 1.0L₀.

A disposable diaper is usually sold in a state in which a single package contains a plurality of diapers, and the package has an indication showing whether it is for a male or female. Accordingly, the indication makes it possible to distinguish whether the disposable diaper is for a male or female. Individual disposable diapers taken out from the package may or may not have the indication showing whether it is for a male or female. Even when individual disposable diapers do not have any indication by letters for showing whether it is for a male or female, decorations on the individual disposable diapers may serve to distinguish between those for a male and for a female. For example, usually, disposable diapers with blue-based designs are for a male, whereas those with pink-based designs are for a female. In other words, the colors of designs on individual disposable diapers may be helpful to distinguish disposable diapers for a male from those for a female.

The present invention is also defined by way of the following non-limiting features CI to C7, El to E8 and Jl to J7, which are not specific to the detailed embodiments described above.

CI. A disposable diaper comprising a liquid- permeable top sheet made of a nonwoven fabric, a liquid- impermeable back sheet, and an absorber interposed between the top sheet and the back sheet, wherein the disposable diaper further comprises a hydrophilic and liquid-permeable absorptive and diffusive sheet between the top sheet and the absorber;

the top sheet has a plurality of ridges and furrows extending in parallel in a front-back direction of the disposable diaper on a surface of the top sheet

contacting a wearer's skin, a surface of the top sheet opposite to the surface thereof contacting the wearer's skin being flat;

the ridges have a higher weight per unit area than the furrows;

when a front-back direction length of the absorber is L₀, in a case of the disposable diaper for a male, a front end of the absorptive and diffusive sheet is in a position of 0.0L₀ to 0.10L₀ from a front end of the absorber and a rear end of the absorptive and diffusive sheet is in a position of 0.50Lo to 0.85L₀ from the front end of the absorber, whereas, in a case of the disposable diaper for a female, the front end of the absorptive and diffusive sheet is in a position of 0.2L₀ to 0.35Lo from the front end of the absorber and the rear end of the absorptive and diffusive sheet is in a position of 0.7L₀ to 1. OLo from the front end of the absorber.

C2. The disposable diaper according to CI, wherein the absorptive and diffusive sheet has a density larger than a density of the furrows of the top sheet and smaller than a density of the ridges of the top sheet.

C3. The disposable diaper according to CI or C2, wherein a leg-surrounding elastic member is provided on both side portions of the disposable diaper, and when the disposable diaper is for a male, the front end of the absorptive and diffusive sheet is located further forward than a front end of the leg-surrounding elastic member, whereas when the disposable diaper is for a female, the front end of the absorptive and diffusive sheet is located further rearward than the front end of the leg- surrounding elastic member.

C4. The disposable diaper according to any one of

CI to C3, wherein a fastener target tape is provided on a front waistline region of the disposable diaper, and when the disposable diaper is for a male, a part of the absorptive and diffusive sheet overlaps the target tape, whereas when the disposable diaper is for a female, the absorptive and diffusive sheet is spaced from the target tape .

C5. The disposable diaper according to any one of CI to C4, wherein an opening hole or a portion having a small density is present in the furrows of the top sheet.

C6. A disposable diaper for male comprising a liquid-permeable top sheet made of a nonwoven fabric, a liquid-impermeable back sheet, and an absorber interposed between the top sheet and the back sheet,

wherein the disposable diaper further comprises a hydrophilic and liquid-permeable absorptive and diffusive sheet between the top sheet and the absorber;

the ridges have a higher weight per unit area than the furrows;

the absorptive and diffusive sheet is provided on a part of a region in a surface direction of the absorber; when a front-back direction length of the absorber is Lo, a front end of the absorptive and diffusive sheet is in a position of 0.0L₀ to O.lOLo from a front end of the absorber and a rear end of the absorptive and

diffusive sheet is in a position of 0.50L₀ to 0.85L₀ from the front end of the absorber;

a leg-surrounding elastic member is provided on both side portions of the disposable diaper, and the front end of the absorptive and diffusive sheet locates further forward than a front end of the leg-surrounding elastic member; and

a fastener target tape is provided on a front waistline region of the disposable diaper, and a part of the absorptive and diffusive sheet overlaps the target tape.

C7. A disposable diaper for a female comprising a liquid-permeable top sheet made of a nonwoven fabric, a liquid-impermeable back sheet, and an absorber interposed between the top sheet and the back sheet,

the ridges have a higher weight per unit area than the furrows;

the absorptive and diffusive sheet is provided on a part of a region in a surface direction of the absorber; when a front-back direction length of the absorber is L₀, a front end of the absorptive and diffusive sheet is in a position of 0.2Lo to 0.35Lo from a front end of the absorber and a rear end of the absorptive and

diffusive sheet is in a position of 0.7Lo to 1.0L₀ from the front end of the absorber;

a leg-surrounding elastic member is provided on both side portions of the disposable diaper, and the front end of the absorptive and diffusive sheet locates further rearward than a front end of the leg-surrounding elastic member; and

a fastener target tape is provided on a front waistline region of the disposable diaper, and the absorptive and diffusive sheet is spaced from the target tape.

El. A disposable diaper comprising a liquid- permeable top sheet made of a nonwoven fabric, a liquid- impermeable back sheet, and an absorber interposed between the top sheet and the back sheet, wherein:

the disposable diaper further comprises a

the ridges have a higher weight per unit area than the furrows;

where the length of the absorber in the front-back direction is L₀, in the case of a disposable diaper for a male, the front end of the absorptive and diffusive sheet is positioned 0.0L₀ to 0.10L₀ from the front end of the absorber and the rear end of the absorptive and diffusive sheet is positioned 0.50L₀ to^'0.85L₀ from the front end of the absorber; and in the case of a disposable diaper for a female, the front end of the absorptive and diffusive sheet is positioned 0.20L₀ to 0.35L₀ from the front end of the absorber and the rear end of the absorptive and diffusive sheet positioned 0.70L₀ to 1.0L₀ from the front end of the absorber. E2. The disposable diaper according to El, wherein the absorptive and diffusive sheet has a density larger than the density of the furrows of the top sheet and smaller than the density of the ridges of the top sheet.

E3. The disposable diaper according to El or E2, wherein a leg-surrounding elastic member is provided on both side portions of the disposable diaper, and when the disposable diaper is for a male, the front end of the absorptive and diffusive sheet is located further forward than the front end of the leg-surrounding elastic member, whereas when the disposable diaper is for a female, the front end of the absorptive and diffusive sheet is located further rearward than the front end of the leg- surrounding elastic member.

E4. The disposable diaper according to any one of

El to E3, wherein a fastener target tape is provided on a front waistline region of the disposable diaper, and when the disposable diaper is for a male, a part of the absorptive and diffusive sheet overlaps the target tape, whereas when the disposable diaper is for a female, the absorptive and diffusive sheet does not overlap the target tape.

E5. The disposable diaper according to any one of El to E4, wherein an opening hole or a portion having a small density is present in the furrows of the top sheet.

E6. The disposable diaper according to E5, wherein said portion having a small density has a density of 0.015 g/cm³ or less.

E7. The disposable diaper according to any one of E4 to E6, which is a disposable diaper for male

comprising a liquid-permeable top sheet made of a

the disposable diaper further comprises a

hydrophxlic and liquid-permeable absorptive and diffusive sheet between the top sheet and the absorber; the top sheet has a plurality of ridges and furrows extending in parallel in a front-back direction of the disposable diaper on a surface of the top sheet

contacting a wearer's skin, a surface of the top sheet opposite to the surface contacting the wearer's skin being flat;

the ridges have a higher weight per unit area than the furrows;

where the length of the absorber in the front-back direction is L₀, the front end of the absorptive and diffusive sheet is positioned 0.0L₀ to 0.10L₀ from the front end of the absorber and a rear end of the

absorptive and diffusive sheet is in a position of 0.50L₀ to 0.85Lo from the front end of the absorber;

a leg-surrounding elastic member is provided on both side portions of the disposable diaper, and the front end of the absorptive and diffusive sheet is located further forward than a front end of the leg-surrounding elastic member; and

a fastener target tape is provided on the front waistline region of the disposable diaper, and a part of the absorptive and diffusive sheet overlaps the target tape.

E8. The disposable diaper according to any one of E4 to E6, which is the disposable diaper for a female comprising a liquid-permeable top sheet made of a

the disposable diaper further comprises a

contacting a wearer's skin, a surface of the top sheet opposite to the surface · contacting the wearer's skin being flat;

the ridges have a higher weight per unit area than the furrows ;

the absorptive and diffusive sheet is provided on a part of the absorber corresponding to an absorption zone, which absorption zone includes and surrounds the position of urination of the wearer;

when the length of the absorber in the front-back direction is L₀, the front end of the absorptive and diffusive sheet is positioned 0.20L₀ to 0.35L₀ from a front end of the absorber and the rear end of the

absorptive and diffusive sheet is positioned 0.70L₀ to l.OLo from the front end of the absorber;

a leg-surrounding elastic member is provided on both side portions of the disposable diaper, and the front end of the absorptive and diffusive sheet is located further rearward than a front end of the leg-surrounding elastic member; and

a fastener target tape is provided on the front waistline region of the disposable diaper and the

absorptive and diffusive sheet does not overlap the target tape.

INDUSTRIAL APPLICABILITY

A disposable diaper according to the present

invention can be suitably used as a disposable diaper for a baby and infant.

REFERENCE SIGNS LIST

1: Disposable di

20: Chassis

30: Flap portion

40: Back sheet : Absorber

: Absorbing member

, 53: Covering sheet

: Front end of absorber

: Top sheet

: Ridge

: Furrow

, 80: Elastic member

: Absorptive and diffusive sheet

: Front end of absorptive and diffusive sheet: Rear end of absorptive and diffusive sheet0: Fastener target tape

0: Fastener tape

0: Web

1: Ridge

2: Furrow

0: Suction drum

0: Ejection section

1: Fluid flow

Claims

1. A disposable diaper comprising a liquid- permeable top sheet made of a nonwoven fabric, a liquid- impermeable back sheet, and an absorber interposed between the top sheet and the back sheet,

the top sheet has a plurality. of ridges and furrows extending in parallel in a front-back direction of the disposable diaper on a surface of the top sheet contacting a wearer's skin, a surface of the top sheet opposite to the surface thereof contacting the wearer's skin being flat;

the ridges have a higher weight per unit area than the furrows;

the absorptive and diffusive sheet is provided on a part of a region in a surface direction of the absorber; and

when a front-back direction length of the absorber is Lo, in a case of the disposable diaper for a male, a front end of the absorptive and diffusive sheet is in a position of 0. OLo to 0.10L₀ from a front end of the absorber and a rear end of the absorptive and diffusive sheet is in a position of 0.50L₀ to 0.85L₀ from the front end of the absorber, whereas, in a case of the disposable diaper for a female, the front end of the absorptive and diffusive sheet is in a position of 0.2Lo to 0.35L₀ from the front end of the absorber and the rear end of the absorptive and diffusive sheet is in a position of 0.7L₀ to 1.0L₀ from the front end of the absorber.

2. The disposable diaper according to claim 1, wherein the absorptive and diffusive sheet has a density larger than a density of the furrows of the top sheet and smaller than a density of the ridges of the top sheet.

3. The disposable diaper according to claim 1 or 2, wherein a leg-surrounding elastic member is provided on both side portions of the disposable diaper, and when the disposable diaper is for a male, the front end of the absorptive and diffusive sheet is located further forward than a front end of the leg-surrounding elastic member, whereas when the disposable diaper is for a female, the front end of the absorptive and diffusive sheet is located further rearward than the front end of the leg- surrounding elastic member.

4. The disposable diaper according to any one of claims 1 to 3, wherein a fastener target tape is provided on a front waistline region of the disposable diaper, and when the disposable diaper is for a male, a part of the absorptive and diffusive sheet overlaps the target tape, whereas when the disposable diaper is for a female, the absorptive and diffusive sheet does not overlap the target tape.

5. The disposable diaper according to any one of claims 1 to 4, wherein an opening hole or a portion having a small density is present in the furrows of the top sheet .

6. The disposable diaper according to claim 4 or 5, which is the disposable diaper for male comprising a liquid-permeable top sheet made of a nonwoven fabric, a liquid-impermeable back sheet, and an absorber interposed between the top sheet and the back sheet,

wherein the disposable diaper further comprises a hydrophilic and liquid-permeable absorptive and diffusive sheet between the top sheet and the

absorber;

the top sheet has a plurality of ridges and furrows extending in parallel in a front-back

direction of the disposable diaper on a surface of the top sheet contacting a wearer's skin, a surface of the top sheet opposite to the surface thereof contacting the wearer's skin being flat; the ridges have a higher weight per unit area than the furrows;

the absorptive and diffusive sheet is provided on a part of a region in a surface direction of the absorber;

when a front-back direction length of the absorber is L₀, a front end of the absorptive and

diffusive sheet is in a position of 0. OLo to O.lOLo from a front end of the absorber and a rear end of the

absorptive and diffusive sheet is in a position of 0.50L₀ to 0.85L₀ from the front end of the absorber;

a leg-surrounding elastic member is provided on both side portions of the disposable diaper, and the front end of the absorptive and diffusive sheet locates further forward than a front end of the leg- surrounding elastic member; and

7. The disposable diaper according to claim 4 or 5, which is the disposable diaper for a female comprising a liquid-permeable top sheet made of a nonwoven fabric, a liquid-impermeable back sheet, and an absorber interposed between the top sheet and the back sheet,

absorber;

direction of the disposable diaper on a surface of the top sheet contacting a wearer's skin, a surface of the top sheet opposite to the surface thereof contacting the wearer's skin being flat;

the ridges have a higher weight per unit area than the furrows; the absorptive and diffusive sheet is provided on a part of a region in a surface direction of the absorber;

when a front-back direction length of the absorber is L₀, a front end of the absorptive and diffusive sheet is in a position of 0.2Lo to 0.35L₀ from front end of the absorber and a rear end of the

absorptive and diffusive sheet is in a position of 0.7Lo to 1. OLo from the front end of the absorber;

a leg-surrounding elastic member is provided on both side portions of the disposable diaper, and the front end of the absorptive and diffusive sheet locates further rearward than a front end of the leg- surrounding elastic member; and

a fastener target tape is provided on a front waistline region of the disposable diaper, and the absorptive and diffusive sheet does not overlap the target tape.